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DIY Stompboxes => Building your own stompbox => Topic started by: Mark Hammer on October 18, 2012, 09:28:41 AM

Title: Harmonic Percolator - make one!
Post by: Mark Hammer on October 18, 2012, 09:28:41 AM
As I noted on the "crowdsourcing" thread I started, I put together a clone of an Interfax Harmonic Percolator last night, and fell in love instantly.  VERY nice pedal, and so simple to make.  Must have taken me less than an hour, start to finish, on perfboard.

I won't provide any samples because mine sounds exactly like the one Steve Albini demos on the Youtube video.  Eerily so, right down to the false octave-down that comes in now and then.  I used a 2N3565 (hfe around 150) and a 2SB172 (hfe 52-54), and some unmarked germanium diodes.   I don't mention this because you MUST use these values.  Rather that's what I used, and if have something similar, it won't NOT work.  I had socketed the transistors in preparation for swapping different ones in and out.  But the first pair I stuck in nailed it.  Lucky, I guess.

I've made and owned somany different distortions, it takes something truly different to capture my imagination/fancy.  This does it.  Pinkjimi, this is your next stupid pedal trick.  :icon_wink:
Title: Re: Harmonic Percolator - make one!
Post by: midwayfair on October 18, 2012, 09:42:54 AM
+1 on this! However, I'll add:

Adding a switch for to go to a pair of silicon diodes (or my favorite "silicon range" diode, OA126) in a symmetric arrangement also gives you a fan-bloody-tastic low-medium gain OD in the same box.
Title: Re: Harmonic Percolator - make one!
Post by: electrosonic on October 18, 2012, 10:38:04 AM
Can you link to the schematic used? I seem to remember their being some differences among the published versions out there.

Thanks,
Andrew.
Title: Re: Harmonic Percolator - make one!
Post by: Mark Hammer on October 18, 2012, 10:42:05 AM
I used the 2007 George Giblet drawing that was posted here.  If you do an image search for the pedal, you'll find it in the first dozen hits.
Title: Re: Harmonic Percolator - make one!
Post by: midwayfair on October 18, 2012, 10:51:29 AM
Can you link to the schematic used? I seem to remember their being some differences among the published versions out there.

Thanks,
Andrew.


Madbean also has the "concensus" schematic values and the "Albini" schematic values in his Pepperspray document:
http://www.madbeanpedals.com/projects/PepperSpray/docs/PepperSpray.pdf
Title: Re: Harmonic Percolator - make one!
Post by: Electron Tornado on October 18, 2012, 11:26:45 AM
Tim Escobedo has a schematic in his circuit snippets collection for his take on this, calling it the Harmonic Jerkulator. Anyone know how it compares? 
Title: Re: Harmonic Percolator - make one!
Post by: Jazznoise on October 18, 2012, 01:01:00 PM
I actually have this sitting on my breadboard at the moment, just waiting on the chance to get to pick the college's techs stock to see if they've anything that might do it. They did have AC128's when I needed em, so you never know..

Actually? Would a low hfe AC128 do the trick? I'll have to try it myself obviously but I'm just wondering has anyone done it!
Title: Re: Harmonic Percolator - make one!
Post by: Mark Hammer on October 18, 2012, 01:29:30 PM
Madbean also has the "concensus" schematic values and the "Albini" schematic values in his Pepperspray document:
http://www.madbeanpedals.com/projects/PepperSpray/docs/PepperSpray.pdf
There are differences between what I made, using the Giblet drawing, and what Bean shows in the Pepperspray.
1) he shows R1=51k, I used 220k
2) he shows R2=91k, I used 20k
3) he shows R3=3M9, I used 750k
4) He shows C4=2u2, I used 100nf
5) He shows C5, I did not use C5

That doesn't make the Pepperspray erroneous or uninteresting, but those values are not required to make for an interesting tone, or may simply be needed in the event of the specific transistors used.  A low hfe AC128 is also likely not required.  However, we often associate distortion with higher gain devices, and can have a trickier time finding germanium devices in the parts bin with hfe >70.  I can happily say this is not required for aural success.
Title: Re: Harmonic Percolator - make one!
Post by: midwayfair on October 18, 2012, 03:33:39 PM
Madbean also has the "concensus" schematic values and the "Albini" schematic values in his Pepperspray document:
http://www.madbeanpedals.com/projects/PepperSpray/docs/PepperSpray.pdf
There are differences between what I made, using the Giblet drawing, and what Bean shows in the Pepperspray.
1) he shows R1=51k, I used 220k
2) he shows R2=91k, I used 20k
3) he shows R3=3M9, I used 750k
4) He shows C4=2u2, I used 100nf
5) He shows C5, I did not use C5

That doesn't make the Pepperspray erroneous or uninteresting, but those values are not required to make for an interesting tone, or may simply be needed in the event of the specific transistors used.  A low hfe AC128 is also likely not required.  However, we often associate distortion with higher gain devices, and can have a trickier time finding germanium devices in the parts bin with hfe >70.  I can happily say this is not required for aural success.

I didn't mean to suggest that any particular values are required. Mine deviated from all specs. ;)

However, he gives two BOMs: One is the "Albini" version with the values shown in his schematic, and the other is the "Stock" (concensus) version, which matches most of the values you give, including the option to omit C5.
Title: Re: Harmonic Percolator - make one!
Post by: DougH on October 18, 2012, 04:04:38 PM
Hey Mark, Do you have a direct link for the schematic? I can't find George's anymore.
Title: Re: Harmonic Percolator - make one!
Post by: Mark Hammer on October 18, 2012, 04:23:24 PM
Go here: http://topopiccione.atspace.com/PJ24HarmonicPercolator.html
Title: Re: Harmonic Percolator - make one!
Post by: LucifersTrip on October 18, 2012, 04:49:16 PM
I had this one bookmarked:
http://www.diystompboxes.com/pedals/Percolator.gif

...I would like to see the schematic that Mark used that correlated to his changes in R's and C's

...and Mark, please at least post test voltages if you're going to ask us to "make one" !!!!

thanx
Title: Re: Harmonic Percolator - make one!
Post by: davent on October 18, 2012, 06:09:00 PM
Looks like George's schematic drawing was hosted on Geocities.
Title: Re: Harmonic Percolator - make one!
Post by: newperson on October 18, 2012, 08:48:33 PM
lets see some images of your layout work!
Title: Re: Harmonic Percolator - make one!
Post by: Mark Hammer on October 18, 2012, 10:12:02 PM
The layout is immaterial, plus there are some "video issues" to be attended to on my machine that preclude pics.

The voltages, however, are as follows (battery = 9.7V):

Q2:  C-3.24  B-2.12  E-1.58

Q1: E-1.58  B-1.49  C-1.39

Weird, huh?  I quickly stuck an OC70 (hfe 43) in place of Q1 and got very similar readings withn a few millivolts.

I mistakenly reported Q1 as a 2SB172.  It is in fact a 2SB33 (I keep them in the same parts drawer).  I made a 3-knob Tonebender with a set of 2SB33s, and it sounded pretty damn fine.
Title: Re: Harmonic Percolator - make one!
Post by: Mark Hammer on October 18, 2012, 10:57:08 PM
Okay, video card problem solved.  1=Orpheum, 2=Bosstone, 3=Octavia, 4=Dist+, 5= Percolator, 6=almost a Controfuzz
(http://img.photobucket.com/albums/v474/mhammer/6-in-1.jpg)
Title: Re: Harmonic Percolator - make one!
Post by: Quackzed on October 18, 2012, 11:08:31 PM
 :icon_cool:
you could use a 2p6t rotary on that thing!
Title: Re: Harmonic Percolator - make one!
Post by: newperson on October 19, 2012, 12:47:31 AM
Thank you for the image.  I love to see other people's work and since you post so much I was particularly interested in yours.  It was six times as nice to see.

Title: Re: Harmonic Percolator - make one!
Post by: LucifersTrip on October 19, 2012, 12:51:31 AM
The layout is immaterial, plus there are some "video issues" to be attended to on my machine that preclude pics.
The voltages, however, are as follows (battery = 9.7V):

Q2:  C-3.24  B-2.12  E-1.58

Q1: E-1.58  B-1.49  C-1.39



Excellent...thank you very much!

that is one of the few oddballs I still haven't built, since I never was able to find a conclusive, "complete" schematic with voltages.

edit:
looking over my bookmarks, I now realize why I never built one. the built reports and voltages from everyone are all over the place. here're a few of the links I saved that I thought might help:

http://www.diystompboxes.com/smfforum/index.php?topic=68649.msg550551#msg550551

http://www.diystompboxes.com/smfforum/index.php?topic=55987.msg434050#msg434050

http://www.diystompboxes.com/smfforum/index.php?topic=55987.msg432770#msg432770

Title: Re: Harmonic Percolator - make one!
Post by: glops on October 19, 2012, 02:28:50 AM
Yea, I etched the madbean board and did the albini specs. More of an overdrive but has its own unique character but I just feel lIke there's something more magical that's not quite being released from it. Gonna mod it to Marks specs as that seems to be the way to go.
Title: Re: Harmonic Percolator - make one!
Post by: Mark Hammer on October 19, 2012, 08:58:16 AM
:icon_cool:
you could use a 2p6t rotary on that thing!
Um, you DO realize that's what I'm doing, right?
Title: Re: Harmonic Percolator - make one!
Post by: alparent on October 19, 2012, 09:07:33 AM
Okay, video card problem solved.  1=Orpheum, 2=Bosstone, 3=Octavia, 4=Dist+, 5= Percolator, 6=almost a Controfuzz
(http://img.photobucket.com/albums/v474/mhammer/6-in-1.jpg)

That's what you get when an effects guy says he's working on is six pack!
Title: Re: Harmonic Percolator - make one!
Post by: Mark Hammer on October 19, 2012, 12:24:39 PM
I'm just glad it's not a two-four!! :icon_lol: (Canadian joke)
Title: Re: Harmonic Percolator - make one!
Post by: pinkjimiphoton on October 20, 2012, 01:25:30 PM
screw it, maybe i WILL build one of these.

i built the harmonic jerkulator as one of my first builds, and it lived on my pedalboard until recently. it makes a great "helper" pedal to boost other things.

the percolator is more overdrive/fuzz, the jerkulator is more of a nice transistor preamp boost imho.

mark... i guess i know what i'll be doing later today.

stupid pedal trick coming...with the percolator AND the jerkulator, so peeps can see what they sound like.

that said, i did breadboard the perc, and liked the jerk better. but...we'll see, i do need one in my collection.

god...i'm gonna have to sell off stuff soon, i'm running out of room to store things...6 milk crates full of pedals at this point, not counting multieffects, racks, standalones..

and i've built 75% of them. it's madness!!

thanks mark for the inspiration bro! ;)
Title: Re: Harmonic Percolator - make one!
Post by: pinkjimiphoton on October 20, 2012, 01:51:07 PM
 mark,,
is this the exact schem you used?

any subs, or close-enoughs?

(http://topopiccione.atspace.com/pjimages/HarmonicPercolator.sch.png)
Title: Re: Harmonic Percolator - make one!
Post by: Mark Hammer on October 20, 2012, 02:12:52 PM
You're welcome, I think.  :icon_lol:

I stuck about 96% to the schem.  Differences are:

56nf instead of 50nf input cap (.05uf kind of disappeared with big ceramic disc caps)
Regular electro instead of tantalum for 47uf
2SB33 instead of 2N404
100k output pot instead of 50k

None of that should have made much of a difference.

You're gonna like this.  I know you by now.  :icon_wink:
Title: Re: Harmonic Percolator - make one!
Post by: Pyr0 on October 20, 2012, 02:17:04 PM
I must try this one again. I built one on vero using Sabro's layout which is based on a schematic by ringworm, but most of the component values are totally different to the one above. I never bothered to box it up as it just didn't sound right. I should be able to swap them in my existing board.
Title: Re: Harmonic Percolator - make one!
Post by: pinkjimiphoton on October 20, 2012, 04:03:07 PM
You're welcome, I think.  :icon_lol:

I stuck about 96% to the schem.  Differences are:

56nf instead of 50nf input cap (.05uf kind of disappeared with big ceramic disc caps)
Regular electro instead of tantalum for 47uf
2SB33 instead of 2N404
100k output pot instead of 50k

None of that should have made much of a difference.

You're gonna like this.  I know you by now.  :icon_wink:


hahahah!! yah, i guess by now... well, i dicked around with DIYLC, and here's an as yet unverified veroboard layout as per brian's layout for the peppermill...

but i mean, looking at it, it looks ok to me. i'm beginning to trust my layout abilities, even if i do seem to screw up the actual construction. lol...

(http://i605.photobucket.com/albums/tt137/pinkjimiphoton/HARMONICPERCOLATORVEROPJP.png)

for ref, brian's schematic....i didn't bother with the switch, i'll just want the ge's most likely

(http://i605.photobucket.com/albums/tt137/pinkjimiphoton/pepperspray.png)

i don't believe there's any mistakes...i was gonna dick around building a fuzzrite, but this has piqued my interest again, so i'll build it up.
gonna probably sub to next closest values, but may try dialing in some with a file.

you know me...pretty lazy!! so next closest values will probably be it.

if someone would be so kind to peek at my latest disgrace, i'd love that. before i build it, for a change, i mean.. ;)
Title: Re: Harmonic Percolator - make one!
Post by: Jazznoise on October 20, 2012, 05:21:31 PM
So, Mark, got any clips? We can have a race between Jimi and yourself!  ;D
Title: Re: Harmonic Percolator - make one!
Post by: pinkjimiphoton on October 20, 2012, 05:41:27 PM
it's ON!!

 :icon_mrgreen:

mark is gonna win, cuz i am not gonna get a chance until at least tomorrow or monday to start building. ;)
Title: Re: Harmonic Percolator - make one!
Post by: Paul Marossy on October 20, 2012, 11:58:00 PM
I tried to do one on perf real quick but all I can get it to do is squeal. I must have a mistake somewhere but I can't find it.  :icon_mad:
Title: Re: Harmonic Percolator - make one!
Post by: pinkjimiphoton on October 21, 2012, 12:31:06 AM
at least you got a squeal...i got nothin', pisses me off as i mix and matched resistors to get the "proper" values.

have tried several combos of transistors, nothing. the voltages seem reasonable. oy.

i'll try this pos tomorrow, and try and sus it out.

i don't see any mistake with my vero, anybody else see something screwy?
Title: Re: Harmonic Percolator - make one!
Post by: Quackzed on October 21, 2012, 02:40:42 AM
try it without the diodes? other than that r2 and r4 seem to be the main bias resistors, a little smaller bigger on either one may swing the bias into/out of the sweet spot. 1st id try a 100k variable resistor on r2. tweak and see if you can get it to pass sound... a variable 100k on r2 will probably work, if not swap the 100k pot over to r4 and try it there instead, one or the other should allow it to bias up... if not and all else is correct, socket the trannies and try different gains hfe's... not tested but a logical approach anyway...

Title: Re: Harmonic Percolator - make one!
Post by: Paul Marossy on October 21, 2012, 07:26:40 AM
R2? On my schematic R2 is the pot right before the output jack...
Title: Re: Harmonic Percolator - make one!
Post by: Jazznoise on October 21, 2012, 08:38:33 AM
Try making C4 smaller and removing C5, Jimi. The schematic version I'm looking at has a 100nF between the base of both transistors, but no cap from there to ground.

It's been linked already here, but to clarify: http://topopiccione.atspace.com/pjimages/HarmonicPercolator.sch.png
Title: Re: Harmonic Percolator - make one!
Post by: Gus on October 21, 2012, 08:42:53 AM
Mark Hammer

The 47uf cap that "AC grounds" the emitters does matter.  A Tantalum 47uf will do a better job than a 47uf Aluminum electrolytic.

The HP is two gain stages in series with the power supply being divided up between the stages.  The biasing used for each stage makes sure there is no DC current path except the via collector resistors and transistors (ignoring any leakage paths in the caps)

I have built two circuits somewhat like this one a Si PNP, NPN transistor version and one a Si NPN version.  You need to get the stages adjusted just right for what you want in the sound.  I used a 100uf Aluminum electrolytic at the emitters

Even the output volume control value makes a difference due to the loading of the "top" transistor collector

EDIT  pinkjimiphoton measure the emitter node voltage to ground measure the "top" and "bottom" collector to ground voltages.  For adjusting bias I would adjust the collector to base resistor values.  This circuit has a number of things that interact and adjusting it might take a few iterations.

There are a few threads at this site about the HP it might be good to find them all and combine them and/or have a link to the threads.
Title: Re: Harmonic Percolator - make one!
Post by: Quackzed on October 21, 2012, 10:11:35 AM
Quote
R2? On my schematic R2 is the pot right before the output jack...
 
i was referring to the pepper spray schem, on the toopocione sp? schem it would be r3 & r4...
but the collector to base resistor values may be better to alter the bias, as gus mentioned...
just tryin to help... probably a mistake on my part...
Title: Re: Harmonic Percolator - make one!
Post by: Gus on October 21, 2012, 10:54:18 AM
pinkjimiphoton

Looking at the vero, noted the part numbers do not match the vero part numbers?

no need for R00 the 100K control acts as an antipop
The 3.9meg R4 is wrong you have it Q2 B to +9 it should be Q2 B to C
R5, C7, D2 and D3 are not wired correctly
Title: Re: Harmonic Percolator - make one!
Post by: pinkjimiphoton on October 21, 2012, 11:50:28 AM
pinkjimiphoton

Looking at the vero, noted the part numbers do not match the vero part numbers?

no need for R00 the 100K control acts as an antipop
The 3.9meg R4 is wrong you have it Q2 B to +9 it should be Q2 B to C
R5, C7, D2 and D3 are not wired correctly

hmmm,....on the pepperspray schem linked to earlier in the thread, r4 goes from b+ to q2 base, not b to c. is the madbean schem wrong?

10-4 on R5 and d2/d3...i completely see my screw up now, the high side of R5 should be connected to the high side of D2...right now, there's no output possible, as it doesn't even connect, tho c7 should still be connecting to the output, i just shouldn't have any clipping.

but c7 as shown on the pepperspray schem i posted is coming from the b + rail, right to the top of the output pot, which is what my vero has, too, it matches the schematic i was working from. weird.

so you're saying the 3.9 r4 should be q2 b&c? where do i take the output from, q2 c?

i looked thru all the threads on the HP here yesterday, and left way more confused than when i came in. seems like nothing but conflicting info.

so...the george giblet one is right, correct? cuz looking at it, and comparing it to brians, it's not the same circuit.

ay...it's not the same, my brain hurts, and i definitely just spotted more problems with my vero. it's getting deleted, be back..
Title: Re: Harmonic Percolator - make one!
Post by: Gus on October 21, 2012, 12:07:56 PM
The pepper spray schematic in one of your posts shows the 3.9 meg Q2 B to C.  The 91K is the collector resistor for the top transistor.
C7 then connects to the collector and 91k and 3.9meg node and then to the diodes and volume control

The information about the HP is not conflicting.  It seems there were different versions made.  Pick the version you want to build.

Then there are all the different variations of the original that people have built.





Title: Re: Harmonic Percolator - make one!
Post by: pinkjimiphoton on October 21, 2012, 12:18:03 PM
hi gus,
i'm trying to see if i can salvage the board i built, not looking possible, so gonna do a new layout based on the GG schem.
thanks for the help and advice!! be back shortly
Title: Re: Harmonic Percolator - make one!
Post by: pinkjimiphoton on October 21, 2012, 12:55:07 PM
ok, could probably have made this smaller or a little more elegant, but i wanted to see if i could salvage the original vero..
well, yes, i could salvage the board, but not the circuit. it has the same dimensions as the last one, but instead of going by brian's schem (which i fail'd epically on translating, sorry madbean!!! it's me, not your schem, i am an eeeeeeediot) i went by the george giblet schem instead.

gonna try and build this up instead..i MAY try to do it all on the original vero just to prove to myself i could...but ...naaaaaaaaaaah...

please...advice? did i get it right this time? it looks ok to me, but then, it did yesterday, too...

(http://i605.photobucket.com/albums/tt137/pinkjimiphoton/INTERFAXHARMONICPERCOLATORVERO1.png)

this is the george giblet "consensus" schematic, which i used for the above layout:

(http://i605.photobucket.com/albums/tt137/pinkjimiphoton/HarmonicPercolatorsch.png)

i noticed the part numbers are missing a few things, which i'm assuming are power filter and diode, which i'll just mount on the power jack.

look kosher? i hope? :D
Title: Re: Harmonic Percolator - make one!
Post by: pinkjimiphoton on October 21, 2012, 02:26:47 PM
ok, this one works. ;)

EDIT:  THIS VERO LAYOUT IS VERIFIED

i gotta play with it some later to get the best fit for the trannys...right now, gotta mp16b (russian 404) in q1, and i dunno what in q2..but it's working.

surprisingly, other than the ge diode clipper, it SOUNDS like the harmonic jerkulator. not a whole lot of difference, other than the hj cleaning up better with the volume control.

the sub harmonix are there, everything, tho more subtle...probably cuz the transistors in there are too hot. but tonally?

escobedo pretty much nailed it, surprised how little mojo the actual circuit has over his adaptation. my opinion may change once i get the right transistors in there, but i dunno...stay tuned! ;)
Title: Re: Harmonic Percolator - make one!
Post by: digi2t on October 21, 2012, 04:58:36 PM
Try an '828 in Q2. The ones I gave you are in the ball park for hfe with what's marked on the schematic.

Just for fun  :icon_mrgreen:.
Title: Re: Harmonic Percolator - make one!
Post by: bluesdevil on October 21, 2012, 06:58:06 PM
I built this one a few years back and could get the low octave ghost notes by using a very leaky transistor for Q1. Can't recall the exact hfe, but I'm pretty sure over 100hfe. I would definitely play around with this on the breadboard before committing to solder. Didn't keep notes so sure as hell can't remember what parts values I went with..... damn!!!!
Title: Re: Harmonic Percolator - make one!
Post by: pinkjimiphoton on October 21, 2012, 07:03:36 PM
Try an '828 in Q2. The ones I gave you are in the ball park for hfe with what's marked on the schematic.

Just for fun  :icon_mrgreen:.

i have the real low gain one ya gave me for the superfuzz, i ended up using one of the other 828's there...will try tonite, report back! ;)
Title: Re: Harmonic Percolator - make one!
Post by: pinkjimiphoton on October 21, 2012, 07:05:08 PM
I built this one a few years back and could get the low octave ghost notes by using a very leaky transistor for Q1. Can't recall the exact hfe, but I'm pretty sure over 100hfe. I would definitely play around with this on the breadboard before committing to solder. Didn't keep notes so sure as hell can't remember what parts values I went with..... damn!!!!

lower gain super high leakage is the way to go...

or ya can get by with a 3906/3904 pair, probably. that's what's in escobedo's variant.
Title: Re: Harmonic Percolator - make one!
Post by: pinkjimiphoton on October 21, 2012, 08:03:29 PM
ok, dicked around some with the cct, and this is where i settled. i can still get a fair cleanup with my guitar volume control, and when cranked it sounds like the demo's i've heard...maybe an rch more polite. can't try it thru an amp at stage volume til tomorrow nite.

q1: 2n404 ge (top hat)
hfe : 43
e: 1.80
b: 1.68
c: 1.31

q2: bc639 (had to twist the legs around so b and c were right, as the 639 is ecb, not ebc) si
hfe 139
e:1.81
b: 2.38
c:2.81
this transistor Dino gave me for my superfuzz..nice sounding, as soon as i tried it the circuit came to life. tried a whole bunch of ge's for q1, some 2sc ge's i had, ac 128 (or was that 127?) mp16b, etc etc...
the 2n404, again, just seemed to bring it to life.

like mark said... build one!!

mark...thanks for the inspiration, bud, gus, thanks for the advice, everybody...thanks...build one!! they seem pretty oblivious to transistors, higher gain just makes it ruder..in some cases, rude to the point of significant 2nd harmonic.

the combo i used lets it clean up like a fuzzface...but sounds NOTHING like a fuzzface. going on my live board i think.

power supply was 9.47v

i get a little bit of a high pitched whine, so i gotta play with adding a real small cap or two to the cct to nuke it...may go away once it's boxed tho.

nice circuit, but for real, the escobedo one sounds real good, and real close.

i also used 1n34a's for the clipper, 100k l for harmonics and 50k l for level.
for the 91 k, i used an 82k and a 10k in series), for the 750k i used a 510k and a 220k in series..10k x 2 in series for 20k. worked right out of the gate.

i'll try and do a "stupid pedal tricks" tomorrow with the harmonic jerkulator to compare the two.
look forward to hearing mark's!!

the vero i did could probably be condensed a little bit, but it's already pretty small, and verified, if anyone wants a go at it. ;)
Title: Re: Harmonic Percolator - make one!
Post by: pinkjimiphoton on October 21, 2012, 09:16:30 PM
(http://i605.photobucket.com/albums/tt137/pinkjimiphoton/598804_4383085908214_14557696_n.jpg)
Title: Re: Harmonic Percolator - make one!
Post by: Mark Hammer on October 21, 2012, 09:34:36 PM
Congrats!  I knew you'd you'd find something to tickle yourself with in that circuit.

It really doesn't sound like much else, but in a very good way.

Soundclips are a little awkward at the moment, but I'll see what I can do when the circumstance presents itself.  In the meantime, rock on.
Title: Re: Harmonic Percolator - make one!
Post by: pinkjimiphoton on October 21, 2012, 11:33:50 PM
all good mark!
indeed, it's different in a very cool way!! i like how at lower guitar volumes it does exactly what it says...makes a lot of very warm nice harmonics, and gets raunchy when you crank it. it's like a distortion that thinks it's a fuzz...real controllable.
i think doug hammond nailed it years ago  here: http://www.diystompboxes.com/smfforum/index.php?topic=68649.msg550551#msg550551
his suggestions for gain on the two transistors really seems to nail it.
a really leaky low-gain ge that probably wouldn't work in anything else is perfect for this thing.

i gotta question tho...since one of the transistors is ge, should we try using a reverse biased ge diode in parallel with e and b (or was it b and c? i gotta look) like the old plate to plate brit face to make it more impervious to temp changes?

living in new england, i'm sure this thing could get a bit fickle...my fuzzface is a lot more stable since i added that diode, and went to a different SI q2 in it.
Title: Re: Harmonic Percolator - make one!
Post by: midwayfair on October 22, 2012, 09:42:43 AM
a really leaky low-gain ge that probably wouldn't work in anything else is perfect for this thing.

You can even put the PNP in backwards! It'll do some oscillation stuff that way but otherwise sound very similar. (I had actually thought mine was backwards for a while before I paid more attention to the schematic, and it turned out to be oriented correctly.) The tolerance/bullet proofness of the Ge is one of the main draws of this circuit for me, especially because it uses a PNP (which is cheap) in an NPN circuit without any voltage inverter nonsense.

i gotta question tho...since one of the transistors is ge, should we try using a reverse biased ge diode in parallel with e and b (or was it b and c? i gotta look) like the old plate to plate brit face to make it more impervious to temp changes?

living in new england, i'm sure this thing could get a bit fickle...my fuzzface is a lot more stable since i added that diode, and went to a different SI q2 in it.

It's emmiter to base ... normally. However, remember the transistor is flipped around.

You can try it, I guess, but I didn't notice any temperature instability with mine, and I used it in a non-air conditioned house and a basement in the same recording session and never noticed an appreciable sound difference.
Title: Re: Harmonic Percolator - make one!
Post by: pinkjimiphoton on October 22, 2012, 10:30:18 AM
LOL!!

I HEAR YA ON THE FLIP IT EITHER WAY THING!!!

i find that on a LOT of GE fuzzes...if they're warm enough, it doesn't seem to matter at all!!

i was just curious about the diode trick, cuz here i have to change transistors a couple times a year...there's the summer ones, and the winter ones, in my fuzzface.
Title: Re: Harmonic Percolator - make one!
Post by: pinkjimiphoton on October 22, 2012, 06:32:24 PM
here ya go, the harmonic percolator:

Title: Re: Harmonic Percolator - make one!
Post by: Paul Marossy on October 22, 2012, 06:53:48 PM
Maybe I'll try again using this schematic - http://i605.photobucket.com/albums/tt137/pinkjimiphoton/HarmonicPercolatorsch.png
My first attempt has resulted in nothing but an oscillator circuit. I have given up on even trying to get it to work, it will only squeal like a pig being murdered.  :icon_confused:

At least now I have that video from pinkjimiphoton to use as a reference point.
Title: Re: Harmonic Percolator - make one!
Post by: pinkjimiphoton on October 22, 2012, 06:57:50 PM
that's it paul, rock it bro!!
Title: Re: Harmonic Percolator - make one!
Post by: inductor on October 22, 2012, 09:00:24 PM

I modified the HP-1 abit based on Mr. Bill's values. Low Hfe 2n404's seem to work better - I have a bunch of high hfe 2n404's that I'll be trying the piggy back trick with. I removed the first pot, I think rolling off your guitar's volume knob works just as well. I believe the 1.5nf cap tightens up the fuzz it's still nasty/gnarly.

This schematic is abit dated just the +9 supply/led is different now. OH and I use a 50k vol pot.

http://www.inductorguitars.com/wp-content/uploads/2011/03/MP-1-schematic.png (http://www.inductorguitars.com/wp-content/uploads/2011/03/MP-1-schematic.png)



There are a 4 youtube demos of my pedal. Don't want to spam...
Title: Re: Harmonic Percolator - make one!
Post by: midwayfair on October 22, 2012, 10:06:11 PM
here ya go, the harmonic percolator:



Great job. Very rich sounding, one of the best "concensus schematic" demos I've heard for sure.

... great, now I need to make another one of these ....
Title: Re: Harmonic Percolator - make one!
Post by: Mark Hammer on October 22, 2012, 11:01:24 PM
I liked the first one so much that I made a 2nd one for a buddy this evening.  Same schematic, except that the transistors were a 2SB175 with hfe around 52, and a 2N3904 with an hfe somewhere above 150.  Raunchier than the first one I made, but capable of the same tone.  I ran it through a Zombie Chorus set for a delay range that straddled the border of chorus and flanging.  Oh man, does it ever sound like the characteristic grunt/growl of a Leslie.
Title: Re: Harmonic Percolator - make one!
Post by: newperson on October 23, 2012, 04:55:33 AM
this thread got me poking around again about this pedal.  thought this link would be nice if someone would like to see the gut shots of one.

http://acapella.harmony-central.com/showthread.php?1008997-Rarer-than-hen-s-teeth

Title: Re: Harmonic Percolator - make one!
Post by: pinkjimiphoton on October 23, 2012, 11:37:01 AM
i used it live last night for the first time, it sounds a lot different thru my stage amp than my ruby..
definitely sounds better thru the smaller amp, much richer.
thru the big amp, it was kinda bright and shrieky, not quite as warm.
that said...before my fuzzface or klon it was amazing....and was doing all the stuff in albini's demos.
i think it needs to feed a moderately overdriven amp to really do it's thing as in steve's video demo of it.
so today, i may try and mellow it out a little with a strategically placed small cap, or i may try and find a less noisy/lower gain q2.
it's a bit above unity at full tilt, so that's good, too.

i likes it. gotta tweek it in a bit tho i think.
Title: Re: Harmonic Percolator - make one!
Post by: pinkjimiphoton on October 23, 2012, 11:56:03 AM
guys, any suggestions on how to make it a tad less shrieky?
i love how warm it sounds with the small amp, but thru my princeton it needs to shave about an octave off the top end..

and i gotta hit the solder joints, as it's popping and cracking a little...

i didn't, but i reccomend shielded cable to/from the switch.

off to mess with it...

and then i gotta find the jerkulator, for part 2 of SPT, the shootout
Title: Re: Harmonic Percolator - make one!
Post by: midwayfair on October 23, 2012, 12:34:45 PM
guys, any suggestions on how to make it a tad less shrieky?
i love how warm it sounds with the small amp, but thru my princeton it needs to shave about an octave off the top end..

and i gotta hit the solder joints, as it's popping and cracking a little...

i didn't, but i reccomend shielded cable to/from the switch.

off to mess with it...

and then i gotta find the jerkulator, for part 2 of SPT, the shootout

220-470pF or so across the volume pot might be the ticket. Easy to remove if it isn't, too.

Be careful about killing too much treble in this circuit early on (by e.g. increasing the 100pF cap) -- you can kill a lot of what makes it special.

Stock it has plenty of treble, but I wouldn't call it shrieky ... But then again, I like treble boosters, so maybe this guy's plenty is another guy's too much. (This is mine through a clean blackface-ish amp: http://www.youtube.com/watch?v=UoW2NUZewPY)
Title: Re: Harmonic Percolator - make one!
Post by: digi2t on October 23, 2012, 01:12:58 PM
Quote
220-470pF or so across the volume pot might be the ticket. Easy to remove if it isn't, too.

Uglyface fix.  :icon_wink:
Title: Re: Harmonic Percolator - make one!
Post by: Pyr0 on October 23, 2012, 01:13:36 PM
You could also try putting in that 1nf5 cap on the collector of Q1 to ground like in the pepper spray schematic.
Title: Re: Harmonic Percolator - make one!
Post by: pinkjimiphoton on October 23, 2012, 02:35:33 PM
thanks guys,
i will try both, see what sounds best. re-tubing my little homebrew monster at the moment, gonna let it idle a while.
i love that serendipitous feeling ya get when ya can plug in brand new power tubes and the freekin' bias is already close enough for rock and roll.

love.

so...either 1.5n  like the pepperspray, or small cap across the pot..i'm assuming you mean from input of the pot to ground, right?

sometimes i like a 100p cap across the input and wiper of the output pot on fuzzes, so you can turn it down and not lose all your sparkle.
wondering if maybe the combo may be magical..as this thing sounds best full blast, imho.

that way, i could tame the high end, BUT make it stay more consistent as turned down, i'm thinking..keep the tone the same, but still have volume control.

gonna go play. stay tuned! ;)

thanks brothers!! :D
Title: Re: Harmonic Percolator - make one!
Post by: midwayfair on October 23, 2012, 03:00:32 PM
thanks guys,
i will try both, see what sounds best. re-tubing my little homebrew monster at the moment, gonna let it idle a while.
i love that serendipitous feeling ya get when ya can plug in brand new power tubes and the freekin' bias is already close enough for rock and roll.

love.

so...either 1.5n  like the pepperspray, or small cap across the pot..i'm assuming you mean from input of the pot to ground, right?

sometimes i like a 100p cap across the input and wiper of the output pot on fuzzes, so you can turn it down and not lose all your sparkle.
wondering if maybe the combo may be magical..as this thing sounds best full blast, imho.

that way, i could tame the high end, BUT make it stay more consistent as turned down, i'm thinking..keep the tone the same, but still have volume control.

gonna go play. stay tuned! ;)

thanks brothers!! :D

Actually, I didn't realize you weren't using the 1.5nF cap. Do that first, as that's actually a HUGE amount of treble cut.

I meant putting the cap on lugs 1 and 3 of the output volume (that is, to ground). I don't think the other method of creating a treble bleed is appropriate here, especially because you've stated you prefer yours full blast.

Good luck ... hope you find a nice balance so it sounds good on both the Ruby and your stage amp. :)
Title: Re: Harmonic Percolator - make one!
Post by: pinkjimiphoton on October 23, 2012, 03:46:22 PM
i put a 22n across the volume wiper to ground.
huge difference...still a little hiss, but nothing like it was. gonna try a smaller cap, get a little more "sizzle" back.

it cleans up beautifully right now, but...i want a little bit more high end.. thinking, to my ear, 2.2n should be about perfect..

still messing with it.

part of the problem was i wired the dang switch backwards on the output.

and took the output from the INPUT of the volume pot to the switch, instead of the output.  :icon_redface: :icon_redface: :icon_redface:

oops...figured that out when i tried putting it in the amp and noticed the volume worked in bypass.  :icon_eek:

so i swapped it around, and discovered i'd totally f'd it up. lol...note to self: use more than two colours of hook up wire!! ;)

stay tuned.. i have a feeling around 220p is gonna be the magic number, should give me about 2 octaves more high end, harmonic wise.

Title: Re: Harmonic Percolator - make one!
Post by: pinkjimiphoton on October 23, 2012, 04:35:42 PM
You could also try putting in that 1nf5 cap on the collector of Q1 to ground like in the pepper spray schematic.


ok, i just tried that. i didn't disconnect the cap across the volume pot, but imho, BINGO.

no more earwigs, and when ya turn the guitar down you still get the same tone. right on, pyro, good call!!

so... 1.5 (i used 1n)n cap (i used a green chicklet) between c and ground nukes the earwigs, and a 22n cap from wiper to ground on the level pot (i used, again, a chicklet) tames the rest. you lose a rch of ultra high end sparkle maybe (not enough to matter imho) but you nuke the noise down to like, boss pedal level. gonna try and videe it right quick..brb
Title: Re: Harmonic Percolator - make one!
Post by: pinkjimiphoton on October 23, 2012, 04:53:13 PM
Title: Re: Harmonic Percolator - make one!
Post by: pinkjimiphoton on October 23, 2012, 05:15:20 PM
revised vero

(http://i605.photobucket.com/albums/tt137/pinkjimiphoton/ihpnoisereduce.png)
Title: Re: Harmonic Percolator - make one!
Post by: digi2t on October 23, 2012, 05:22:22 PM
DAMN YOU BROTHER!!!!....... DAMN.... YOU!!!!!!

All parts ordered.

Including some exotic ones.

Yes.... glass resistors.

Guilty as charged.  :icon_twisted:
Title: Re: Harmonic Percolator - make one!
Post by: pinkjimiphoton on October 23, 2012, 06:16:35 PM
lol

paybacks...   :icon_mrgreen:
Title: Re: Harmonic Percolator - make one!
Post by: Mark Hammer on October 23, 2012, 06:43:24 PM
Nice, ain't it?  :icon_biggrin:
Title: Re: Harmonic Percolator - make one!
Post by: digi2t on October 23, 2012, 07:37:53 PM
I`m soooo glad you guys are on my side.

I think.....

 :icon_lol:
Title: Re: Harmonic Percolator - make one!
Post by: Pyr0 on October 23, 2012, 08:25:33 PM
That sounds good Jimi
Title: Re: Harmonic Percolator - make one!
Post by: Morocotopo on October 23, 2012, 08:31:14 PM
I hate you guys.

I HAD to make this, so Mark, if I take longer to make the Polyphase schematic, you know whose fault it is! Well, we can include Jimi there with his videos too!

 :icon_mrgreen:

Used the George Giblet schem. R1 is 2M8. Q1 is a 2SB175A, Hfe:60, leakage 147 uA. Q2 is a 2N3904, Hfe:167. Added a tone control, an A250K pot in parallell with the vol control, with a 6n8 cap from it to ground.  1N60 diodes (germanium). Tried a higher Hfe tranny for Q2, a 2N2222 close to 200, but it was howl city! Actually, with my guitar, the problem was that the bridge pickup fed back like crazy, seems to be the mounting springs are too loose, I could feel it shaking in my hand like mad. Neck one not so much.

Ok, I made a little sound file, just grabbed the guitar and made it, didnīt even tune it.
335 with humbuckers, direct into soundcard. Amp sim soft, set to a Twin, bright switch on, controls more or less at mid point. A bit of verb and ambience. The thing is on the breadboard, so noisy. Since itīs not a real amp, no acoustic feedback, and doesnīt have the live ampīs low end oomph and high freq hiss and stuff. with the amp the tone control is much more dramatic in itīs sweep, helps get rid of the brittle-y highs, depending how you set the ampīs controls. I really like the sort of "spongy" attack on the notes. In the sound file I play the same thing with the tone closed and then with the tone open, and later some noodling and guitar vol control fiddling. Doesnīt clean up as much as I want, that could be taken care of with a lower Hfe Q2 I believe, but I quite like the "all controls on full" sound, so...
Quite feedbacky with the 335 and a Hot rod Deluxe amp, in a nice way.
The file:

http://soundcloud.com/truemostro/harm-perc-with-tone-control
Title: Re: Harmonic Percolator - make one!
Post by: Mark Hammer on October 23, 2012, 08:45:18 PM
Well if that's how you're wasting your time, then I take full credit.

That's how mine sounds.  And yeah, the all-knobs-to-10 is fun because the sound is quite responsive to how hard and where you pick.  A hard pick-strum of a chord above a Tele bridge pickup gets this lovely "struzz" sound that's like bacon crackling (I'm not eating it, rabbi, I'm just listening to it!  :icon_lol: ).  Switch to neck pickup and its a different sound, back off on the volume and again its a different sound.  So it's not like you even need to turn the harmonics control down all that much to get different tones, although I need to turn down to around 3:00 on the one I made the other day to nail what you got.

Clearly, from the long and informative 2008 thread, we are not alone in our admiration for this simple and pretty forgiving circuit.  But I'm happy to have provoked a little interest in it again, such that others could have some of the same pleasure.
Title: Re: Harmonic Percolator - make one!
Post by: Morocotopo on October 23, 2012, 08:56:03 PM
Credited.

Havenīt yet listened carefully to picking sensitivity, will do. And maybe try some lower Hfe Q2īs, to see if I can reach a satisfying balance between gain and cleanup ability. But itīs hard getting low Hfe silicons...

Yet another thing to box. I might try to fit this into the super duper mini boxes, but how will I fit two 16 mm. pots in there?

No, I canīt get 9 mm. ones here in Argentina, so donīt say it. ::)
Title: Re: Harmonic Percolator - make one!
Post by: Paul Marossy on October 24, 2012, 12:06:00 AM
I hate this stupid circuit. I've rebuilt it and I can still only get it to squeal at various frequencies depending on how the knobs are set. No matter what transistors I use it just oscillates at a higher or lower frequency depending on what PNP transistor I use. When I play my guitar thru it, it sounds good if you ignore the constant oscillation.

I don't get it. I guess I'm just stupid for even trying.
Title: Re: Harmonic Percolator - make one!
Post by: Morocotopo on October 24, 2012, 12:38:12 AM
Paul, donīt despair. Have you tried another guitar? As I said, I discovered that what was feeding back in my case were the guitar pickups themselves, not even the strings, and when I tried a higher Hfe Q2 the thing was in constant oscillation. And this circuit seems very prone to feedback, so it might be that the problem is not there but provoked by it...
Title: Re: Harmonic Percolator - make one!
Post by: Mark Hammer on October 24, 2012, 09:12:07 AM
I hate this stupid circuit. I've rebuilt it and I can still only get it to squeal at various frequencies depending on how the knobs are set. No matter what transistors I use it just oscillates at a higher or lower frequency depending on what PNP transistor I use. When I play my guitar thru it, it sounds good if you ignore the constant oscillation.

I don't get it. I guess I'm just stupid for even trying.
Silly question to ask, considering your extensive experience building pedals, but is it possible you've connected something that, in the drawing, is actually not connected?
Title: Re: Harmonic Percolator - make one!
Post by: Paul Marossy on October 24, 2012, 10:13:30 AM
Paul, donīt despair. Have you tried another guitar? As I said, I discovered that what was feeding back in my case were the guitar pickups themselves, not even the strings, and when I tried a higher Hfe Q2 the thing was in constant oscillation. And this circuit seems very prone to feedback, so it might be that the problem is not there but provoked by it...

It does it with no signal at all going to the circuit. If I can't use it with my guitar, there's no point in even using the thing. Don't know if it matters at all, but my guitar has only humbuckers on it.

Silly question to ask, considering your extensive experience building pedals, but is it possible you've connected something that, in the drawing, is actually not connected?

I don't think so. I've used two different schematics, both with the same end result. I must be doing something wrong, but I don't know what.  :icon_confused:
Title: Re: Harmonic Percolator - make one!
Post by: Morocotopo on October 24, 2012, 11:14:46 AM
Paul, I know you have experience in building, but Iīll respectfully suggest some things that come to mind. Probably you have already tested them, but, sometimes another personīs look can be helpful.

- Input wire shielded/far from other wires?
- Defective trannys?
- In the Giblet schem, C3 seems to be connected to Q1īs base, but actually doesnīt (no connecting dot where lines cross)
- PNP/NPN right?
- Too high Hfe in one of the trannys?
- General PCB/breadboard shielding, like for example laying it on top of a grounded aluminum sheet?
- Power? batt, power supply? Feedback trough the power/ground to other circuits/amp/etc? The thing doesnīt have power filtering at all. Perhaps try a R/C there?

Well, thatīs whart comes to mind now. Maybe it will help.
Title: Re: Harmonic Percolator - make one!
Post by: Paul Marossy on October 24, 2012, 11:30:51 AM
- Input wire shielded/far from other wires?
- Defective trannys?
- In the Giblet schem, C3 seems to be connected to Q1īs base, but actually doesnīt (no connecting dot where lines cross)
- PNP/NPN right?
- Too high Hfe in one of the trannys?
- General PCB/breadboard shielding, like for example laying it on top of a grounded aluminum sheet?
- Power? batt, power supply? Feedback trough the power/ground to other circuits/amp/etc? The thing doesnīt have power filtering at all. Perhaps try a R/C there?

Moving around input wire does nothing, it's not shielded. I've tried multiple transistors, they just vary the oscillation from crazy to insane.
Yes, PNP & NPN
I've kept the Hfe as low as possible in Q1 & Q2, still oscillates no matter what.
It's not currently shielded in any way. It sounds like it's trying to pick up some RFI, but I don't think that is the cause of my oscillation problem.
On my first build, I tried the capacitor/resistor on the power supply, still oscillated like crazy. I've only powered it with a battery so far.

If I pull Q2 out of the socket, the crazy oscillalation stops. Current Q2 has an Hfe of about 100. 2N5089 sounds the same, just a little more gainey. If I use a really low Hfe in Q1 position, no fuzz of any sort. IIRC, the oscillation will stop if either pot is almost at zero. Harmonics pot has the largest affect on the amount of oscillation. 
Title: Re: Harmonic Percolator - make one!
Post by: midwayfair on October 24, 2012, 11:49:31 AM
- Input wire shielded/far from other wires?
- Defective trannys?
- In the Giblet schem, C3 seems to be connected to Q1īs base, but actually doesnīt (no connecting dot where lines cross)
- PNP/NPN right?
- Too high Hfe in one of the trannys?
- General PCB/breadboard shielding, like for example laying it on top of a grounded aluminum sheet?
- Power? batt, power supply? Feedback trough the power/ground to other circuits/amp/etc? The thing doesnīt have power filtering at all. Perhaps try a R/C there?

Moving around input wire does nothing, it's not shielded. I've tried multiple transistors, they just vary the oscillation from crazy to insane.
Yes, PNP & NPN
I've kept the Hfe as low as possible in Q1 & Q2, still oscillates no matter what.
It's not currently shielded in any way. It sounds like it's trying to pick up some RFI, but I don't think that is the cause of my oscillation problem.
On my first build, I tried the capacitor/resistor on the power supply, still oscillated like crazy. I've only powered it with a battery so far.

If I pull Q2 out of the socket, the crazy oscillalation stops. Current Q2 has an Hfe of about 100. 2N5089 sounds the same, just a little more gainey. If I use a really low Hfe in Q1 position, no fuzz of any sort. IIRC, the oscillation will stop if either pot is almost at zero. Harmonics pot has the largest affect on the amount of oscillation. 


is your PNP oriented correctly? Try flipping it around. They should be connected at the emiters.
Title: Re: Harmonic Percolator - make one!
Post by: Paul Marossy on October 24, 2012, 11:53:31 AM
Yes, I checked the orientation of the PNP already. It'll do it if reversed too.
Title: Re: Harmonic Percolator - make one!
Post by: Morocotopo on October 24, 2012, 12:24:55 PM
Donīt know if itīs on breadboard, but, I -think- a bad part (r, c)? A pain to check, but...
Title: Re: Harmonic Percolator - make one!
Post by: Paul Marossy on October 24, 2012, 01:54:19 PM
Donīt know if itīs on breadboard, but, I -think- a bad part (r, c)? A pain to check, but...

I don't think it's a bad part. I suspect that I am going to have to monkey around with the value of R2 connected to Q1.

Can someone post the voltages they have on the pins of Q1 & Q2?
Title: Re: Harmonic Percolator - make one!
Post by: Morocotopo on October 24, 2012, 02:00:36 PM
Paul in my build mentioned above, I get:

Power: 9,12V

Q1 - 2SB175A - Hfe: 60 - Leakage: 147 uA
C: 1,36
B: 1,43
E: 1,54

Q2 - 2N3904 - Hfe: 167
C: 3,34
B: 1,40
E: 1,56

My R1 is 2M8. The rest is the same
Title: Re: Harmonic Percolator - make one!
Post by: pinkjimiphoton on October 24, 2012, 02:13:38 PM
http://www.diystompboxes.com/smfforum/index.php?topic=99596.msg874231#msg874231

paul, check my voltages earlier in the thread, the link give hfe and voltages.

too high gain...i mean, anything over 100, and it WILL feedback...even by itself. it's gainy, so it seems to oscillate.

which method did you use to construct? my lame vero in this thread is verified, and works great.

just for now.. try adding them two caps, and see if it nukes the oscillation.

if you wanna pm me your snail mail addie, i can send ya some lo gain pnp's if you need them.

you really gotta get this circuit going...it's simple, but tricky. the "consensus" schem is not right, i don't think...as built, it sounded bright and quite shrieky..about 2 octaves too much high end. to my ear, it didn't sound "right"...but them two caps brought it into the albini ballpark i think.

i used this thing last nite, first in line, and tell ya what.. holy SH....err..COW!  it makes a great "fuzzface helper" and i used it all nite. worked great into the fuzzface, the sho, the klon and even the diphonizer. i was impressed.

i had a phatter tone than i've had live in a long time, and the control from the guitar was pretty sick..roll the tone knobs down, and catch some subharmonics...randomly and unexpectedly.

with my strat and the ff after it, i could get inSANE sustains...pretty much endless..

and feedback is different....not what i was used to, but it seems to catch octaves, 3rds 5ths, 6ths etc. pretty cool

you gotta get this thing workin' paul... you'll love it!!!

hey, just for shitzngrinnz, try the ge in q1 backwards. i know it sounds crazy, but it just may work...if the ge is leaky enough for the cct to be happy, it probably doesn't matter.

;)
Title: Re: Harmonic Percolator - make one!
Post by: Paul Marossy on October 24, 2012, 03:02:33 PM
Paul in my build mentioned above, I get:

Power: 9,12V

Q1 - 2SB175A - Hfe: 60 - Leakage: 147 uA
C: 1,36
B: 1,43
E: 1,54

Q2 - 2N3904 - Hfe: 167
C: 3,34
B: 1,40
E: 1,56

My R1 is 2M8. The rest is the same

Thanks, that will help. I'm guessing that probably the Hfe on Q1 is too high and/or I'll have to mess with that Q1 emitter resistor some.
Why did you use so high a value on R1?
Title: Re: Harmonic Percolator - make one!
Post by: Paul Marossy on October 24, 2012, 03:04:11 PM
http://www.diystompboxes.com/smfforum/index.php?topic=99596.msg874231#msg874231

paul, check my voltages earlier in the thread, the link give hfe and voltages.

too high gain...i mean, anything over 100, and it WILL feedback...even by itself. it's gainy, so it seems to oscillate.

which method did you use to construct? my lame vero in this thread is verified, and works great.

just for now.. try adding them two caps, and see if it nukes the oscillation.

Yes, that's probably part of my problem, Q1 Hfe is too high. I built it on perf and triple checked everything.

Which two caps are you referring to? I didn't see anything about that...
Title: Re: Harmonic Percolator - make one!
Post by: Mark Hammer on October 24, 2012, 03:12:55 PM
I built mine on perf, and all those little parts was-a-huggin' each other.  I used sockets for the transistors.  VERY helpful for nailing one's optimal tone...or at least the oscillation thats in the same key as the tune.  :icon_lol:    The machined socket pins are real nice, but you can't always rely on perfect contact with the device.  Sometimes you need to tin the transistor leads to thicken them up enough.
Title: Re: Harmonic Percolator - make one!
Post by: pinkjimiphoton on October 24, 2012, 03:19:48 PM
http://www.diystompboxes.com/smfforum/index.php?topic=99596.msg874231#msg874231

paul, check my voltages earlier in the thread, the link give hfe and voltages.

too high gain...i mean, anything over 100, and it WILL feedback...even by itself. it's gainy, so it seems to oscillate.

which method did you use to construct? my lame vero in this thread is verified, and works great.

just for now.. try adding them two caps, and see if it nukes the oscillation.

Yes, that's probably part of my problem, Q1 Hfe is too high. I built it on perf and triple checked everything.

Which two caps are you referring to? I didn't see anything about that...

damn, dude, you need to read the thread  :icon_mrgreen:

use a 1.5n chiklet between q1 c and ground, and up to a 2.2n cap from level pot wiper to ground.
wiped out most of the oscillation/noise/earwigs.

what about paralleling a couple ge's for q1? should be able to get a lower gain that way, maybe?
Title: Re: Harmonic Percolator - make one!
Post by: Morocotopo on October 24, 2012, 03:28:27 PM
Paul in my build mentioned above, I get:

Power: 9,12V

Q1 - 2SB175A - Hfe: 60 - Leakage: 147 uA
C: 1,36
B: 1,43
E: 1,54

Q2 - 2N3904 - Hfe: 167
C: 3,34
B: 1,40
E: 1,56

My R1 is 2M8. The rest is the same

Thanks, that will help. I'm guessing that probably the Hfe on Q1 is too high and/or I'll have to mess with that Q1 emitter resistor some.
Why did you use so high a value on R1?

Paul, in Madbeanīs Pepper Spray schem some values are different that the ones in Gibletīs schem. That R is 3M9. When I first listened to it, 750K didnīt sound too good (too little distortion if I remember right) so I experimented with that and 2M8 seemed to give the best sound. Nothing more than that.
Title: Re: Harmonic Percolator - make one!
Post by: pinkjimiphoton on October 24, 2012, 03:31:11 PM
I built mine on perf, and all those little parts was-a-huggin' each other.  I used sockets for the transistors.  VERY helpful for nailing one's optimal tone...or at least the oscillation thats in the same key as the tune.  :icon_lol:    The machined socket pins are real nice, but you can't always rely on perfect contact with the device.  Sometimes you need to tin the transistor leads to thicken them up enough.

i buy bagfuls of the machined 6 pin dip sockets,  i cut 'em in half with a dremel, instant GOOD sockets...them SIP strips people sell suck, cuz once ya swap out a few parts, their connectivity goes down hill, and yes, you do have to tin 'em.

the machined ones are best, imho
Title: Re: Harmonic Percolator - make one!
Post by: midwayfair on October 24, 2012, 03:31:28 PM
http://www.diystompboxes.com/smfforum/index.php?topic=99596.msg874231#msg874231

paul, check my voltages earlier in the thread, the link give hfe and voltages.

too high gain...i mean, anything over 100, and it WILL feedback...even by itself. it's gainy, so it seems to oscillate.

which method did you use to construct? my lame vero in this thread is verified, and works great.

just for now.. try adding them two caps, and see if it nukes the oscillation.

Yes, that's probably part of my problem, Q1 Hfe is too high. I built it on perf and triple checked everything.

Which two caps are you referring to? I didn't see anything about that...

My Q1 is ... um, about 40hfe. Even 70 was too high for me. So go loooowww. Sockets! :)
Title: Re: Harmonic Percolator - make one!
Post by: pinkjimiphoton on October 24, 2012, 03:34:34 PM
i tried a bunch of different trannys, and anything over about 45 or so was simply too much.

i have to wonder if the guy from interfax designed this so he could use cheap garbage transistors that would be too low gain/leaky for other circuits.

i tried up to 400hfe, and fuggeddaboudit. even 100 was too damn high.
Title: Re: Harmonic Percolator - make one!
Post by: Paul Marossy on October 24, 2012, 03:41:13 PM
damn, dude, you need to read the thread  :icon_mrgreen:

use a 1.5n chiklet between q1 c and ground, and up to a 2.2n cap from level pot wiper to ground.
wiped out most of the oscillation/noise/earwigs.

what about paralleling a couple ge's for q1? should be able to get a lower gain that way, maybe?

I glanced through it. I can't sit here and read the whole thing while I am here at work. I'll see if these "snubber" caps help anything. Thanks...
Title: Re: Harmonic Percolator - make one!
Post by: pinkjimiphoton on October 24, 2012, 03:43:01 PM
no worries bro, sorry if i came across with a tude, just trying to help man!! ;)

hope ya get it sorted out!!  :icon_mrgreen:
Title: Re: Harmonic Percolator - make one!
Post by: Paul Marossy on October 24, 2012, 03:48:49 PM
no worries bro, sorry if i came across with a tude, just trying to help man!! ;)

hope ya get it sorted out!!  :icon_mrgreen:

No problem.  :icon_cool:
Title: Re: Harmonic Percolator - make one!
Post by: digi2t on October 24, 2012, 05:29:34 PM
OK, here's the skinny...

I've got it on the breadboard. I'm pretty much faithful to the plan(s). I'm using a 2SB176 in Q1, and a PN2222 in Q2. I spent the day trying different trannies, and these two are the cat's ass. Using 1N695 diodes, including a third on the input side, as per the original layout.

The 1K/2.2uF combo to ground on the collector of Q1 is a real kill joy. It really mellows things out, but that's not what I'm here for.

220K is fine between B and C of Q1, but Q2 didn't wake up until I up'd the ante to a 1.5M resistor between it's B and C. Even a 1.2M works pretty well.

I replaced the 20K to ground on Q1's collector with a trimmer. The harmonics really start slapping me in the face when I got down around 4.6K. Far cry from the 20K or even 91K stated on some drawings, but kind of fits in between with 2.7K I've seen on a drawing.

Input cap is a .047uF. Q1C to Q2B cap is .01. I added another .01 between Q1C to ground, because Radio Moscow was sending me the word of God.

The biggest ass kicking was the 1uF cap. I tried a Tant., and an electro, but with a Nichicon Muse bi-polar, the low end bark scared the crap outta me.

If I crank the amp just enough, I feedback harmonics just about everywhere.

Video tomorrow. I'm just too stone deaf right now. :icon_biggrin:
Title: Re: Harmonic Percolator - make one!
Post by: pinkjimiphoton on October 24, 2012, 06:43:29 PM
i may have to build it up with your mods...i have a feeling i'll like 'em!!!  :icon_mrgreen: :icon_mrgreen: :icon_mrgreen: :icon_mrgreen:
Title: Re: Harmonic Percolator - make one!
Post by: Jazznoise on October 24, 2012, 06:52:20 PM
Wow, you guys are certainly outdoing yourselves. That thing sounds amazing, Jimi, I'd consider that feat beer-worthy.

What digi2t is saying makes me think the 91K resistor is more of a current establishing thing than a voltage thing. A factor of 20 of a difference certainly doesn't correlate to what differences we're hearing of. Does Vc or Ve change much with your biasing, digi2t?
Title: Re: Harmonic Percolator - make one!
Post by: Pyr0 on October 24, 2012, 07:40:26 PM
^ digi2t - Interesting. What did you use for the resistor in series with the last 1N695, 2k7 or 4k7 ?
I've a couple of those Nichon 1uf non-polar caps, must try it out tomorrow along with the resistor values you mentioned.

thanks
Title: Re: Harmonic Percolator - make one!
Post by: pinkjimiphoton on October 24, 2012, 07:54:59 PM
thanks chris, a cyber-toast to you, bro.

i can't wait to hear what dino comes up with...he can take some amazing circuits, and make them UNBELIEVABLE, lol!
Title: Re: Harmonic Percolator - make one!
Post by: digi2t on October 25, 2012, 12:21:15 AM
^ digi2t - Interesting. What did you use for the resistor in series with the last 1N695, 2k7 or 4k7 ?
I've a couple of those Nichon 1uf non-polar caps, must try it out tomorrow along with the resistor values you mentioned.

thanks


1K for the resistor in series with the diode. I took that from some gutshot pics of an early original. Here are some numbers from mine;

2SB176 hfe = 115, 0.15mA leakage (Peak Atlas meter)
PN2222 hfe = 190 (TO-92 cases are quieter than the metal heads.)

With the trimmer at around 20K on Q1 collector to ground, at 9.09v supply voltage I can easily get the widely posted voltages of;
PNP 2N404A

E 1.61 v
B 1.46 v
C 1.46 v

NPN 2n3565

E 1.62 v
B 1.93 v
C 2.49 v

or with a tweak,

Q1    E 1.51  B 1.42 C 1.36
Q2    E 1.51  B 2.09 C2.33

but, I found that if I dial down to around 6.8K, and bring the Q1 collector to around .5v, I hit this sweet spot that gives me a slight octave bloom at the end of the notes. Sounds just as raunchy as the higher voltages, but with a little extra mustard. I mean, I've seen drawings that go from 91K, all the way down to 2.7K here. That's why I decided to throw a trimmer in here, and play with it. When you're dialing down, you can hear it getting louder, but obviously, you have to be careful not to go too far to ground.

I tried it with a .022 input cap, and harmonically it does pop more with single coils, but with the humbucker, I lose the grunt. Sticking with the .047 for now, but I might try a .033 to split the difference. Turning down the volume does clean up a lot, and with the neck single coil, I get a real Tele type snap twang. So much so, that I need to dial down the tone a tad.

That's it for now. Video tomorrow. Bedtime now.
Title: Re: Harmonic Percolator - make one!
Post by: Mark Hammer on October 25, 2012, 10:28:28 AM
Thanks for your diligence, Dino.  Much appreciated.

Let's compare the "consensus" drawing against other devices:

HP-1 has....2 transistors, 2 pots, 2 diodes, 5 resistors, 5 caps.

Fuzz Face has...2 transistors, 2 pots, no diodes, 4 resistors, 3 caps

Jordan Bosstone has....2 transistors, 2 pots, 2 diodes, 5 resistors, 4 caps

Fuzz-Rite has...2 transistors, 2 pots, no diodes, 4 resistors, 4 caps

Amazing what one can do with so little, eh?
Title: Re: Harmonic Percolator - make one!
Post by: Paul Marossy on October 25, 2012, 11:35:18 AM
Still haven't got this thing working. I have the transistor voltages & Hfe's in the ballpark with a 2N1108 and a 2N2222, and I've got the oscillation almost under control except when controls at max, but it doesn't sound anything like pinkjimiphoton's video. No creaminess or sustain at all. Just a very mild overdrive, IF I strum the strings hard. I messed with the emitter resistor on Q1 and the resistor between C & B on Q2 too. So far, this build has been a complete utter failure. Why is it that these simple little circuits never $%&*(@+ work for me? I must have lost my touch.  :icon_frown:

EDIT: Not sure if those "snubber" caps I added are helping or hurting. Will try removing the one on the output pot tonight and see what that does. I don't expect to have much luck at this point.
Title: Re: Harmonic Percolator - make one!
Post by: pinkjimiphoton on October 25, 2012, 11:49:12 AM
paul, don't give up man.
it sounds to me like you need to do a continuity check. i've had a lot of problems like that too lately, and have found it usually to be a resistor that's open, particularly if it's standing...it makes enough of a contact to complete the ccct when ya whack it, but is maddening to find.
i've had it happen on a few builds now, including the ross distortion i built a week ago. nothing made any sense, voltages seemed right, and wango...it was one stupid end of one resistor that fell apart as i was de-soldering it to check..on the ross, there's a pot, a cap and a resistor for the gain pot, so it had to be one of the three, and sure enough, that was it.

so check it out man...i KNOW you will find it, and it will be something so freekin' stupid you won't think of it...that happened to me with a few ccts now..

tayda 1/4 watt resistors aren't too sturdy.. ;)
Title: Re: Harmonic Percolator - make one!
Post by: DougH on October 25, 2012, 11:58:46 AM


This sounds really good. From what I remember, this is pretty much what mine sounds like. (Been a while since I used it.) There's that smooth fuzztone when you crank it up that just oozes harmonics. I remember it responded well to just playing without picking, just sliding my left hand fingers around the fretboard and it kept going. Also, the whole overdrive->clean thing it does when you turn down your guitar or the "harmonics" control is well represented here. Nice demo!
Title: Re: Harmonic Percolator - make one!
Post by: pinkjimiphoton on October 25, 2012, 12:02:35 PM
thanks doug! ;)

it is exactly like what you describe...and you almost can't get dissonant harmonic feedback with it. nice box! ;)
Title: Re: Harmonic Percolator - make one!
Post by: Mark Hammer on October 25, 2012, 01:20:48 PM
Paul, your frustration is starting to sound like those TV sitcom scenes where someone experiences, um, er, "masculine" problems.  :icon_lol:

"I don't know what's wrong.  This has never happened to me before...ever....I swear!"
Title: Re: Harmonic Percolator - make one!
Post by: Morocotopo on October 25, 2012, 01:25:14 PM
Still haven't got this thing working. I have the transistor voltages & Hfe's in the ballpark with a 2N1108 and a 2N2222, and I've got the oscillation almost under control except when controls at max, but it doesn't sound anything like pinkjimiphoton's video. No creaminess or sustain at all. Just a very mild overdrive, IF I strum the strings hard. I messed with the emitter resistor on Q1 and the resistor between C & B on Q2 too. So far, this build has been a complete utter failure. Why is it that these simple little circuits never $%&*(@+ work for me? I must have lost my touch.  :icon_frown:

EDIT: Not sure if those "snubber" caps I added are helping or hurting. Will try removing the one on the output pot tonight and see what that does. I don't expect to have much luck at this point.

Paul, are you using a breadboard? Those things eventually fail, the contacts become intermittent/faulty. I recently suffered like mad trying to debug some circuit, till I realized it was the freakinībreadboard! Had to retire it.
Title: Re: Harmonic Percolator - make one!
Post by: pinkjimiphoton on October 25, 2012, 01:27:06 PM
hey mark,
ever notice how those commercials always are tinted blue? ;)
Title: Re: Harmonic Percolator - make one!
Post by: DougH on October 25, 2012, 01:29:14 PM
I just wish someone would explain what the deal is with people holding hands in two separate bathtubs. I don't get it...
Title: Re: Harmonic Percolator - make one!
Post by: Mark Hammer on October 25, 2012, 01:44:14 PM
I just wish someone would explain what the deal is with people holding hands in two separate bathtubs. I don't get it...
They're not holding hands.  They're transferring the soap...securely.  It is slippery, after all.
Title: Re: Harmonic Percolator - make one!
Post by: DougH on October 25, 2012, 02:10:12 PM
I just wish someone would explain what the deal is with people holding hands in two separate bathtubs. I don't get it...
They're not holding hands.  They're transferring the soap...securely.  It is slippery, after all.

Well, that's no fun... Which is kind of my point. What's so fun about sitting in 2 separate bathtubs?
Title: Re: Harmonic Percolator - make one!
Post by: pinkjimiphoton on October 25, 2012, 02:16:18 PM
his and hers, platonic fun? what the heck do ya need the blue pill for then?  :icon_eek:

my world looks more...ummmm....purple, anyways..  :icon_mrgreen:
Title: Re: Harmonic Percolator - make one!
Post by: wavley on October 25, 2012, 02:36:08 PM
I just wish someone would explain what the deal is with people holding hands in two separate bathtubs. I don't get it...
They're not holding hands.  They're transferring the soap...securely.  It is slippery, after all.

Well, that's no fun... Which is kind of my point. What's so fun about sitting in 2 separate bathtubs?

I'm assuming it's because they're married and she's saying "Get that thing away from me, I thought we were past this, I got you a second bathtub am I going to have to get you a separate bathroom? Please stop taking those stupid pills."
Title: Re: Harmonic Percolator - make one!
Post by: Mark Hammer on October 25, 2012, 02:40:17 PM
Well, that's no fun... Which is kind of my point. What's so fun about sitting in 2 separate bathtubs?
Well, for one, you can count who made how many "bubbles" accurately.  :icon_wink:
For another, nobody has to be the one to sit with the spigot jabbing them in the back (been there, done that).

But I get your point.  There are things possible with bench seats (and a little Johnny Mathis) that are not possible with bucket seats.  :icon_wink:

Okay, let's get back on track from frothy bins to fuzzy boxes.
Title: Re: Harmonic Percolator - make one!
Post by: Paul Marossy on October 25, 2012, 02:41:00 PM
Still haven't got this thing working. I have the transistor voltages & Hfe's in the ballpark with a 2N1108 and a 2N2222, and I've got the oscillation almost under control except when controls at max, but it doesn't sound anything like pinkjimiphoton's video. No creaminess or sustain at all. Just a very mild overdrive, IF I strum the strings hard. I messed with the emitter resistor on Q1 and the resistor between C & B on Q2 too. So far, this build has been a complete utter failure. Why is it that these simple little circuits never $%&*(@+ work for me? I must have lost my touch.  :icon_frown:

EDIT: Not sure if those "snubber" caps I added are helping or hurting. Will try removing the one on the output pot tonight and see what that does. I don't expect to have much luck at this point.

Paul, are you using a breadboard? Those things eventually fail, the contacts become intermittent/faulty. I recently suffered like mad trying to debug some circuit, till I realized it was the freakinībreadboard! Had to retire it.

No breadboard, this is on perf with only Q1 socketed.
Title: Re: Harmonic Percolator - make one!
Post by: pinkjimiphoton on October 25, 2012, 02:51:11 PM
paul, just for s-m-g's, try turning q1 around 180 degrees. i don't know why but for some reason, it seems to work with some ge transistors, particularly if they're leaky as hell. in some circuits, you can end up getting what you describe when it's in the circuit, even if your meter says it's the other way around..in fact, i had that very problem on mine when i was trying transistors...the one i have in q1 is probably in BACKWARDS...at least from what my meter read.

can't explain it, but sometimes it seems to be just the way it f'n is... keep us posted bud!! you'll get it!!
Title: Re: Harmonic Percolator - make one!
Post by: digi2t on October 25, 2012, 03:05:46 PM
Alright, here's another installment of the "Hen's Tooth Cafe". Spotlight on the HP circuit. First, I'm going with a Russian MP16A, gain of 43, zero leakage. Then, my trusty 2SB176, 112 gain, 0.1mA leakage. I prefer the 2SB176, especially when I roll off the volume. The MP16 is way too ice-picky clean, whereas the 176 is a tad smoother. I did try a Russian GT402V as well, and it was VERY close to the 176 sound wise. Unfortunately, since the collector is part of the casing, the 402 attracts more noise. In a pinch though, you might want to try a 402. It's not too bad, and might be easier/cheaper to get. Might be alright when boxed. I used it in my Gemini Fuzz with pretty good results.

PN2222 in the Q2 slot. I tried a bunch, but this one seems to be the best compromise between gain, and noise. I recommend plastic cases over metals ones, because I found that metal caps (BC10* etc) act as antennas, attracting more noise. 

1N695 diodes, including one to ground on the input side. 1K series resistor for one of the diodes. 100pF cap to ground on the input side.

0.047 input cap. This one seems to cover the most amount of ground between single coils and buckers. If you're using buckers exclusively, might want to try a 0.022.

0.01 cap between the two trannies, including one from Q1C to ground. 150pF cap to ground on Q2C, or else you'll get AM talk radio, all day long. :icon_mrgreen:

Both emmiters are  going to a 47uF electro to ground (normal, not Tant. Didn't have a Tant on hand).

On the output of Q2, I'm using a Nichicon Muse 1uF bi-polar. I just don't know what it is about this cap, but it pops, where all other 1uf (bi, electro, metal film, whatever) seem to be a bit flat.

(http://www.headfishop.com/images/l/201104/13028331760.jpg)

220K FB resistor for Q1, and 1.5M for Q2 (rather than 750K). 750K just didn't cut the mustard for me here. I've seen numbers ranging from 737K, all the way to 3.9M here (Sardonic Albinator). Use your ears.

The 20K resistor to ground for Q1C is a 25K trimmer. I start at about 1.2v on Q1C, but if I move it down to 0.5v, I get a bit of octave bloom on the tail end of the notes. It's subtle, but there. Anywhere between 0.5 to 1.3 volts on Q1C is pretty happy ground. Again, use your ears. Actually, if we examine the Ge side of the Gemini III fuzz, you'll notice that the 91K resistor is a 100K trimpot as well, though it uses a Ge NPN here. I must admit, with a single Ge booster bofore it, the Gemini sounds pretty damn fine, but doesn't clean up 100%. Always a bit of fur around the edges. The Si side of things cleans up glassy clean. Here's the Gemini III schem, for those of you that want to ganger the Ge end of it. Ohhh Harmonic Percolator... I seeeee yoooou!

(http://i214.photobucket.com/albums/cc196/digi2t/Gemini%20Fuzz/Geminischematic_new.jpg)

OK, popcorn's ready, on with the show.... Mustang-o-caster, into the breadboard, into an Ampeg G-212 pushing 2 x 12" Texas Heats. Touch of reverb on the amp.



Oh yeah, on a lark, I stuck a 2N2907 metal can in the Q1 slot. My hand just fell on one, so I thought, "What the flux, lets give it a whirl".
That was just down right stoooopid.... in a good way.
Same set up as the before, with the Q1C voltage at 1.0v. It won't clean up like the Ge when you roll off the volume, rather, it becomes a very mild chunky overdrive. Quite nice actually, think Bad Company "Rock Steady" chunk, but milder. But, crank the volume back up, and it's a freakin' monster. I tried it with my Korina Explorer, with the G-212 volume at 4, which is pretty loud on a G-212. I thought the bloody thing was going to jump out of my hands and beat me senseless.

I think I'm going to need therapy after that one.... :icon_rolleyes:
Title: Re: Harmonic Percolator - make one!
Post by: Kesh on October 25, 2012, 03:32:50 PM
I have some low gain NPN so am going to attempt to reverse the whole circuit, that is a PNP in the high gain slot and positive ground.
Title: Re: Harmonic Percolator - make one!
Post by: pinkjimiphoton on October 25, 2012, 03:51:44 PM
dino, you NAILED it again bro...sounds freekin' great!! mine is a little bit "tamer" cuz i'm snubbing it some...
gonna have to build it as per your instructions. what a sound!!
 :icon_eek: :icon_eek: :icon_eek: :icon_eek: love!!!!
Title: Re: Harmonic Percolator - make one!
Post by: Paul Marossy on October 25, 2012, 04:04:49 PM
paul, just for s-m-g's, try turning q1 around 180 degrees. i don't know why but for some reason, it seems to work with some ge transistors, particularly if they're leaky as hell. in some circuits, you can end up getting what you describe when it's in the circuit, even if your meter says it's the other way around..in fact, i had that very problem on mine when i was trying transistors...the one i have in q1 is probably in BACKWARDS...at least from what my meter read.

can't explain it, but sometimes it seems to be just the way it f'n is... keep us posted bud!! you'll get it!!

I've already tried reversing Q1, with multiple transistors. Same results no matter what I do.  :icon_mad:
Title: Re: Harmonic Percolator - make one!
Post by: digi2t on October 25, 2012, 04:14:09 PM
I have some low gain NPN so am going to attempt to reverse the whole circuit, that is a PNP in the high gain slot and positive ground.

Huh! That should be interesting. Post results please.

dino, you NAILED it again bro...sounds freekin' great!! mine is a little bit "tamer" cuz i'm snubbing it some...
gonna have to build it as per your instructions. what a sound!!
 :icon_eek: :icon_eek: :icon_eek: :icon_eek: love!!!!

Thanks bro. It's a really flexble circuit. A different cap here or there, or a slight change in the bias, can make a difference. Really, I never gave the Pukealator much thought, but I like it. With just the guitar's volume, you can go from glass clean, to gritty, or all the way to a Muff type roar. Interesting little circuit, I must admit.

Thanks to Mark for stirring up the poop-a-laka on this one.  :icon_mrgreen:

I'll whip up a schem and vero for this one later.

@Paul - Oscillation.... hmmm. If I pull the 47uF to ground on the two emitters, it will go into oscillation. Maybe you've got a bum cap? I'm using a normal electro. Check it out.
Title: Re: Harmonic Percolator - make one!
Post by: pinkjimiphoton on October 25, 2012, 04:43:04 PM
dino....

i was lazy, so didn't whip up a new layout, just modified my old one with ms paint... the diy layout file got corrupted, glad i got the pic to redo it with.
;)

anyways...not so concerned with the physical layout, but does this look right to you with the values?
that nichicon cap is 1uf, not .1uf, right?

the other values look right?

(http://i605.photobucket.com/albums/tt137/pinkjimiphoton/ihpmrdigi2tnoisereduce.png)

you really seem to have nailed it well, bro!!! damn you, now i gotta build another one!!!  :icon_twisted: :icon_twisted: :icon_twisted: :icon_twisted:
Title: Re: Harmonic Percolator - make one!
Post by: LP Hovercraft on October 25, 2012, 06:18:12 PM
Cool thread!  I can recall being giddy at the sound of the Percolator driven by Puzzle87's So-Simple Compressor.  I used 2N404, 2N3565, 1n34a, and panasonic dark red film cap in the 1uF slot, but I doubt whether that cap makes too much difference in the overall sound.  I will second the notion that it will do a subtle octave down when pushed hard.  I'm wondering if that has anything to do with the second harmonic amplification touted in the sale literature?
Title: Re: Harmonic Percolator - make one!
Post by: Paul Marossy on October 25, 2012, 06:47:43 PM
@Paul - Oscillation.... hmmm. If I pull the 47uF to ground on the two emitters, it will go into oscillation. Maybe you've got a bum cap? I'm using a normal electro. Check it out.

I'm using a pair of 22uF in parallel because I ran out of 47uF caps. You think 3uF would send it into an oscillation hissy fit? At this point I'm willing to believe just about anything...
Title: Re: Harmonic Percolator - make one!
Post by: Kesh on October 25, 2012, 07:46:59 PM
dino....

i was lazy, so didn't whip up a new layout, just modified my old one with ms paint... the diy layout file got corrupted, glad i got the pic to redo it with.
;)

anyways...not so concerned with the physical layout, but does this look right to you with the values?
that nichicon cap is 1uf, not .1uf, right?

the other values look right?

(http://i605.photobucket.com/albums/tt137/pinkjimiphoton/ihpmrdigi2tnoisereduce.png)

you really seem to have nailed it well, bro!!! damn you, now i gotta build another one!!!  :icon_twisted: :icon_twisted: :icon_twisted: :icon_twisted:
you have obscured the e11 to b11 jumper.

as it is +9V goes through R3 and then nowhere.
Title: Re: Harmonic Percolator - make one!
Post by: digi2t on October 25, 2012, 07:47:44 PM
Cool thread!  I can recall being giddy at the sound of the Percolator driven by Puzzle87's So-Simple Compressor.  I used 2N404, 2N3565, 1n34a, and panasonic dark red film cap in the 1uF slot, but I doubt whether that cap makes too much difference in the overall sound.  I will second the notion that it will do a subtle octave down when pushed hard.  I'm wondering if that has anything to do with the second harmonic amplification touted in the sale literature?

I have 1uF Panasonic metal films, and I did try one. It sounded a tiny bit darker. Just enough for me to say "dull". The Nichicon Muse BP is my choice. I do have some 47uF tantalums coming, so I'll try one when I get it. I think it might have a tough time knocking the Muse off the mountain though.

I tested the forward voltage on various Ge diodes that I have. 1N34, 1N60, and 1N270's all came in around 0.33 to 0.37v on my DMM. The 1N695's come in at 0.26 to 0.28v. I might try some BAT43's in here for shits and giggles.

Here is a vero of what I have on the breadboard right now;

(http://i214.photobucket.com/albums/cc196/digi2t/Harmonic%20Percolator/Harm_Percvero.jpg)

I must apologize to PyrO, I misread the resistor in series with the diode, and told him 1K. It's 10K that I'm using here. I did an A/B test between 1K and 10K, and found that with 1K I was getting a bit more sustain, but didn't get as glassy a clean up when rolling off the volume. 10K is the opposite, better clean up, tad less sustain. I've seen 4.7K spec'd here, so as always, use your ears.
Title: Re: Harmonic Percolator - make one!
Post by: Mark Hammer on October 25, 2012, 08:00:43 PM
One of the things I like most about it is that I feel absolutely no need to incorporate any sort of treble cut control so that I can play clean and bright and then turn the Percolator on without slicing my head off.  It cuts through just enough to be heard, but has no graininess or fizz; just muscle.

Now, the one I just sold a guy yesterday nailed all the muscle well, but lacked the occasional sub-octave that my own manages to get.  So what do the rest of you get in the way of occasional sub-octave, and do the things you do to get some of the octave-up bloom get in the way of the sub-octave?
Title: Re: Harmonic Percolator - make one!
Post by: inductor on October 25, 2012, 08:20:49 PM

I'm using a pair of 22uF in parallel because I ran out of 47uF caps. You think 3uF would send it into an oscillation hissy fit? At this point I'm willing to believe just about anything...

I would say probably not, but I fiddled around with this cap while prototyping. The only way I could get mine to squeal was a low value e-e cap and then it was mostly motorboating.  I did try a 100uf cap but iirc it was less gainy. I tried a high gain & high leaky pnp it became icepicky.
Title: Re: Harmonic Percolator - make one!
Post by: inductor on October 25, 2012, 08:36:53 PM
So what do the rest of you get in the way of occasional sub-octave, and do the things you do to get some of the octave-up bloom get in the way of the sub-octave?

The ones I make have lots of suboctaves. I'm guessing its something to do with the gain/leakiness.
I'm waiting for some parts and I intend to try piggy backing higher gain 2n404's (to get lower gain) and see what it sounds like.
Title: Re: Harmonic Percolator - make one!
Post by: digi2t on October 25, 2012, 08:46:49 PM
One of the things I like most about it is that I feel absolutely no need to incorporate any sort of treble cut control so that I can play clean and bright and then turn the Percolator on without slicing my head off.  It cuts through just enough to be heard, but has no graininess or fizz; just muscle.

Now, the one I just sold a guy yesterday nailed all the muscle well, but lacked the occasional sub-octave that my own manages to get.  So what do the rest of you get in the way of occasional sub-octave, and do the things you do to get some of the octave-up bloom get in the way of the sub-octave?

Quite honestly, I've yet to get any sub-octave, except when I induce feedback. Depending on the note/chord, it might go up, or down, but always adhering to the root. The octave bloom on decay generally occurs at lower (read "sane") volume levels, with a Q1C voltage of between 0.5v and 0.6v.

Maybe if I up the Q1C voltage, I'll get sub-octave? Or, I'll try a 100K trimmer, in place of the 91K above Q2, but it'll probably just tone down the gain more than anything else. Shades of the Gemini III fuzz here. I'll try it tomorrow. Could be that the 2SB176 just isn't leaky enough?  ???

Just for information, these are the voltages from the Gemini III / Percolator section. I realize that it's using two Ge trannies here, but the PNP collector seems to be set close to the same voltage that I'm running.

Q2- AC128 (Q1 in the HP)
E=1.547v
B=0.946v
C=0.769v

Q3- AC176 (Q2 in the HP)
E=1.547v
B=1.586v
C=1.672v


Title: Re: Harmonic Percolator - make one!
Post by: pinkjimiphoton on October 25, 2012, 09:06:27 PM
dino....

i was lazy, so didn't whip up a new layout, just modified my old one with ms paint... the diy layout file got corrupted, glad i got the pic to redo it with.
;)

anyways...not so concerned with the physical layout, but does this look right to you with the values?
that nichicon cap is 1uf, not .1uf, right?

the other values look right?

(http://i605.photobucket.com/albums/tt137/pinkjimiphoton/ihpmrdigi2tnoisereduce.png)

you really seem to have nailed it well, bro!!! damn you, now i gotta build another one!!!  :icon_twisted: :icon_twisted: :icon_twisted: :icon_twisted:
you have obscured the e11 to b11 jumper.

as it is +9V goes through R3 and then nowhere.

point noted, space that out!! will delete this. ;)

here's it corrected...not the whole layout, just jumper put back in.

i'll let dino do his own layout, his always rock! ;)

(http://i605.photobucket.com/albums/tt137/pinkjimiphoton/ihpmrdigi2tnoisereduce.png)

this is fixed, but not previewing right...the original layout was deleted, wtf?
Title: Re: Harmonic Percolator - make one!
Post by: digi2t on October 25, 2012, 09:30:04 PM
Takes time for Photobucket to update. It'll change, don't worry.
Title: Re: Harmonic Percolator - make one!
Post by: pinkjimiphoton on October 25, 2012, 09:33:14 PM
no worries, dino, just wanted to make sure somebody didn't think it was right and get dissappointed.

'sides, now i got YOUR layout to go with. works for me!! ;)
Title: Re: Harmonic Percolator - make one!
Post by: LP Hovercraft on October 25, 2012, 11:51:03 PM
@ Mark-I will have to play with it a bit to see if I can get the Octave up sound.  It seemed to have the best sound (to my ears, anyway) with a leaky ge transistor in q1.  I remember trying a tightly spec'd 2N404 from Small Bear as q1 and it did not sound very good.  Yes, it must be bandwidth limited just at the right place in upper register somehow-one of the few 2 knobbers that truly do not need a tone control. 
Title: Re: Harmonic Percolator - make one!
Post by: DougH on October 26, 2012, 07:07:26 AM
Part of the bandwidth limiting I believe is due to the low input impedance and the way it loads your guitar pickup. The Rangemaster and Fuzz Face both behave the same way. The low impedance load will roll highs off of your guitar signal. And at the same time, when you turn the guitar down it will get clear and bright. I suspect there's not much more to it than that, other than the passive electronics in your guitar which affect it as well But in the end, I believe it's due to the interaction between the guitar circuit and the input to the fuzz circuit.

Title: Re: Harmonic Percolator - make one!
Post by: Mark Hammer on October 26, 2012, 09:59:35 AM
Part of the bandwidth limiting I believe is due to the low input impedance and the way it loads your guitar pickup. The Rangemaster and Fuzz Face both behave the same way. The low impedance load will roll highs off of your guitar signal. And at the same time, when you turn the guitar down it will get clear and bright. I suspect there's not much more to it than that, other than the passive electronics in your guitar which affect it as well But in the end, I believe it's due to the interaction between the guitar circuit and the input to the fuzz circuit.

Which would also imply that it would sound "best" when placed in an uninterrupted path path from the guitar, rather than preceded by anythng between guitar and Percolator that might offer a low-enough output impedance.  Does that strike you as sensible?
Title: Re: Harmonic Percolator - make one!
Post by: pinkjimiphoton on October 26, 2012, 10:39:49 AM
i run it first, before my fuzzface even.
Title: Re: Harmonic Percolator - make one!
Post by: tca on October 26, 2012, 11:11:32 AM
So, I dind't have the parts for the Percolator, so I've breadboard Escobedo's Jerkulator with two pairs of silicon diodes at the output and with the transistors 2N4401/2N4403. I couldn’t believe my ears!! Here is the sound clip from a portable mp3 recorder with a 1W solid state amp (http://www.diale.org/mp3/jercolator.MP3) with a 3'' speaker. Need to fix the frequency response, but it took me about 15m to breadboard it!


Cheers.
Title: Re: Harmonic Percolator - make one!
Post by: DougH on October 26, 2012, 11:49:38 AM
Part of the bandwidth limiting I believe is due to the low input impedance and the way it loads your guitar pickup. The Rangemaster and Fuzz Face both behave the same way. The low impedance load will roll highs off of your guitar signal. And at the same time, when you turn the guitar down it will get clear and bright. I suspect there's not much more to it than that, other than the passive electronics in your guitar which affect it as well But in the end, I believe it's due to the interaction between the guitar circuit and the input to the fuzz circuit.

Which would also imply that it would sound "best" when placed in an uninterrupted path path from the guitar, rather than preceded by anythng between guitar and Percolator that might offer a low-enough output impedance.  Does that strike you as sensible?

Yes.
Title: Re: Harmonic Percolator - make one!
Post by: digi2t on October 26, 2012, 12:01:15 PM
Something struck a chord (pardon the pun) with me last night. I was reading Gus' analysis of the circuit, when this jumped out at me;

Quote
If you look close it is just two simple gain stages in series: HOWEVER the 47uf sets up how much the current drain in each stage interacts. This is most likely the cause of the musical feedback in the video. Work out your gain phase and current draw.
 
The 47uf is most likely one of the big tuning points in the circuit make it bigger and smaller and hear what happens. The emitter node voltage is also important. If it is 9V supply and 4.5V both sections get 4.5V as a supply voltage. If it is 5V the NPN gets 4VDC and the PNP 5VDC. If it is 3VDC the NPN gets 6VDC and the PNP 3VDC etc.
 

Before I go any further, I'll just mention that I added a 100K pot to the input. What DouH said about loading bothered me. So 100k pot in, and no pot on the out, direct to amp. Pot is maxed during my tests.

So, back to what Gus said. I started rummaging through my capacitors, and found two things;
1) If I lower the 47uF to 4.7uF, raise the cap between the two trannies to 0.1u, and work the trimmer on Q1C, then yes, I do get sub-octave. But, in my case, it's not stable, ugly, and I get oscillation as well. If I turn down the 100K pot, it goes away, but the circuit sounds lifeless.
2) If I go with a 6.8uF tantalum, in place of the 47uF, and return my cap between the two trannies to my original value of 0.01uF, a huge grin appears on my face. Now, the octave up bloom appears slightly more pronounced, and my root notes/chords go into feedback at a much more sane amp volume level. The octave bloom just continues to bloom into sweet feedback. OH HAPPY MAN!!
3) THE sweet spot with a 6.8uF tant is now 1.0v on Q1C. Plucking a note while working the trimmer, as soon as I get close to 1.0v, it's... it's... well, let me put it this way; it finds Jesus. :icon_lol:

At the moment my voltages are;

Q1
E - 1.146
B - 1.049
C - 1.015
Q2
E - 1.146
B - 1.675
C - 2.256

Everything else is unchanged on the board, it's as I drew the vero, except for the 6.8uF replacing the 47uF.

Freakin' crazy!! :icon_cool:
Title: Re: Harmonic Percolator - make one!
Post by: wavley on October 26, 2012, 12:01:49 PM
Part of the bandwidth limiting I believe is due to the low input impedance and the way it loads your guitar pickup. The Rangemaster and Fuzz Face both behave the same way. The low impedance load will roll highs off of your guitar signal. And at the same time, when you turn the guitar down it will get clear and bright. I suspect there's not much more to it than that, other than the passive electronics in your guitar which affect it as well But in the end, I believe it's due to the interaction between the guitar circuit and the input to the fuzz circuit.

Which would also imply that it would sound "best" when placed in an uninterrupted path path from the guitar, rather than preceded by anythng between guitar and Percolator that might offer a low-enough output impedance.  Does that strike you as sensible?

Yes.

So, it might be a good idea to try an AMZ pickup sim in this thing if you don't want it first in your rig?  I put one in my fuzz face and it's certainly close enough for rock and roll.
Title: Re: Harmonic Percolator - make one!
Post by: DougH on October 26, 2012, 12:57:52 PM
Part of the bandwidth limiting I believe is due to the low input impedance and the way it loads your guitar pickup. The Rangemaster and Fuzz Face both behave the same way. The low impedance load will roll highs off of your guitar signal. And at the same time, when you turn the guitar down it will get clear and bright. I suspect there's not much more to it than that, other than the passive electronics in your guitar which affect it as well But in the end, I believe it's due to the interaction between the guitar circuit and the input to the fuzz circuit.

Which would also imply that it would sound "best" when placed in an uninterrupted path path from the guitar, rather than preceded by anythng between guitar and Percolator that might offer a low-enough output impedance.  Does that strike you as sensible?

Yes.

So, it might be a good idea to try an AMZ pickup sim in this thing if you don't want it first in your rig?  I put one in my fuzz face and it's certainly close enough for rock and roll.

Yes, you need to treat this like any vintage fuzz with a low input impedance.

And for digi2t: The 100k pot on the input won't affect the impedance much. The input impedance will basically be constrained by the input impedance of the transistor, which is pretty low, typical for a BJT like this. That's why vintage fuzz circuits using BJT transistors typically have low input impedance which loads the guitar pickup and is part of the "sound". Unless you bootstrap the first stage, a la Gus's NPN Boost, a typical BJT gain stage like this will be low Z.
Title: Re: Harmonic Percolator - make one!
Post by: digi2t on October 26, 2012, 01:29:25 PM
Quote
And for digi2t: The 100k pot on the input won't affect the impedance much. The input impedance will basically be constrained by the input impedance of the transistor, which is pretty low, typical for a BJT like this. That's why vintage fuzz circuits using BJT transistors typically have low input impedance which loads the guitar pickup and is part of the "sound". Unless you bootstrap the first stage, a la Gus's NPN Boost, a typical BJT gain stage like this will be low Z.

Got it Doug. I just wanted to eliminate any and all possible variables here. Bit of a pain when something sounds one way on the board, and then different boxed, especially if it's due to cutting corners when I had it on the board. :icon_mrgreen:
Title: Re: Harmonic Percolator - make one!
Post by: digi2t on October 26, 2012, 03:17:53 PM
CRAP!!!

It was too good to be true. Nix on the 6.8uF. I finally got the chance to crank it up more to, ahem, "stage" levels. Problem is the there is a short oscillation "after howl" that occurs whenever you hit chords hard. So, 6.8uF is out.

10uF tant sounds pretty good though. Better than a high-end ELNA cap that I tried. But, 10uF has a drawback; doesn't clean up as well as a 47uF when you roll of the volume. I have a 33uF Philips axial in right now, and I think it's the best compromise to date. Good harmonic content, feedback attainable (though higher volume is needed), and cleans up pretty decent.

I get the feeling this thing is telling me to stay between 22 and 47uF.

I also reduced the cap on Q1C to ground to 0.0047uF. I saw that the Collins clone uses a 0.001 here, but I couldn't hear a difference between 0.001, and nothing. 0.0047 is a good compromise between the 102, and the 103 I was using. It's just enough to kill the noise from the tranny, while being less buzzy than the 0.01.

Ah... the joys of breadboarding! The saga continues...
Title: Re: Harmonic Percolator - make one!
Post by: pinkjimiphoton on October 26, 2012, 03:40:55 PM
yah, them's the breaks bro...

when i first built this, i was amazed...thru my ruby.
when i played it thru my princeton, i realized there was a humongous difference.. a little tweaking tho, and now it sounds pretty awesome!! ;)
Title: Re: Harmonic Percolator - make one!
Post by: Gus on October 26, 2012, 05:36:17 PM
I built two Si versions
One a PNP 2n2907 and NPN 2n2222
And an all NPN 2n2222
I did change the circuit a little I increased the collector currents and adjusted the feedback bias resistors.


pinkjimiphoton
yah, them's the breaks bro...

when i first built this, i was amazed...thru my ruby.
when i played it thru my princeton, i realized there was a humongous difference.. a little tweaking tho, and now it sounds pretty awesome!! ;)

If I adjusted effects for friends of mine I would ask them to bring there stage amp, guitar(s), and signal cords that they used live.  I would then ask the play at stage volume and explain what they wanted to change.  I would adjust the circuit(EQ, gain, bias etc) and then we would test again.  One thing I noticed is often you want a thin sounding effect when tested it at low volumes in a house for distortions and fuzzes at stage volume.  A few things are going on how the players share the frequency range, if the guitar has open back speakers thing can sound bad when the volume is turned up if you have to much bass, and there are other things.

digi2t
Thanks for doing the cap value and type test at the two emitters.  I never got around to testing this tuning point.
Title: Re: Harmonic Percolator - make one!
Post by: Paul Marossy on October 26, 2012, 06:18:13 PM
Well I finally got mine to work. It wouldn't work because I did something so shockingly stupid that I can't even mention it.  :icon_redface:

Anyway, I did the Giblet version with a few tweaks:

Q1 is a 2N1108 with an Hfe of about 62
Q2 is a 2N2222 with Hfe of about 125
R2 is a 510K
C3 & C6 are 0.15uF
R4 is a 50K trimpot. Sounds best to my ears at about 6.8K
50K balance pot
100uF power supply cap added
0.001uF cap from Q1 collector to ground
0.0022uF cap from output of balance pot to ground

(http://www.diyguitarist.com/Images/HPerc1.jpg)
(http://www.diyguitarist.com/Images/HPerc2.jpg)
(http://www.diyguitarist.com/Images/HPerc3.jpg)
Title: Re: Harmonic Percolator - make one!
Post by: pinkjimiphoton on October 26, 2012, 06:43:14 PM
MUST...HAVE...CLIPS!!!!!!!!!!!!!!!!!!!!!!!
[/color]

 :icon_eek: :icon_eek: :icon_eek: :icon_eek: :icon_eek: :icon_eek: :icon_eek:

PROPS ALL AROUND, I HOIST THIS HERE BREWSKY TO ALL YA'LL!

 i found the jerkulator i built, and listened to it a little... i think it has the flavor of the perc, but doesn't have the same sound.
pretty much the only difference i think is gonna be the diode clipper.
Title: Re: Harmonic Percolator - make one!
Post by: digi2t on October 26, 2012, 07:17:16 PM
Quote
Well I finally got mine to work. It wouldn't work because I did something so shockingly stupid that I can't even mention it. 

Way to keep us up at night, wondering...

 ;D
Title: Re: Harmonic Percolator - make one!
Post by: Paul Marossy on October 26, 2012, 07:24:22 PM
Quote
Well I finally got mine to work. It wouldn't work because I did something so shockingly stupid that I can't even mention it. 

Way to keep us up at night, wondering...

 ;D

Ha ha, right. I think this was the dumbest mistake I ever made. My days are just too long sometimes...  :icon_wink:
Title: Re: Harmonic Percolator - make one!
Post by: DougH on October 26, 2012, 09:22:13 PM
How does it sound, Paul? How do you like it?
Title: Re: Harmonic Percolator - make one!
Post by: pinkjimiphoton on October 26, 2012, 10:31:05 PM
c'mon, paul fess up...

i bet i've done  WAYYYYYYYY dumber. probably on every build!! ;)

the important thing is it's alive!!

we need clips!!!! ;)
Title: Re: Harmonic Percolator - make one!
Post by: Paul Marossy on October 26, 2012, 10:44:42 PM
How does it sound, Paul? How do you like it?

Sounds pretty good I think. Need to spend some quality time with it to really get to know it better...  :icon_lol:
Title: Re: Harmonic Percolator - make one!
Post by: Morocotopo on October 27, 2012, 11:50:16 AM
Well I finally got mine to work. It wouldn't work because I did something so shockingly stupid that I can't even mention it.  :icon_redface:

Paul, you know weīll bother you till you tell us what the problem was...

Confess!!!!!

 :icon_mrgreen: :icon_mrgreen:

Iīve done every possible thing to make my circuits NOT work, such as forgetting to put the ICīs in the board, not connecting power, parts orientation wrong, misplaced parts, etc etc. You think that after some time, you are an "experienced builder", but then the dumbest thing brings you back to earth. Thatīs life.
Congrats on making it work.
Title: Re: Harmonic Percolator - make one!
Post by: Paul Marossy on October 27, 2012, 01:49:14 PM
OK, I had it unboxed and had the input and output jack grounds connected together, but forgot to connect them to the circuit ground. Really really really dumb mistake. That's what happens when you get up at 4:00am, work 10 hours and then try to build a circuit at the end of the day when you are exhausted.  :icon_lol:
Title: Re: Harmonic Percolator - make one!
Post by: pinkjimiphoton on October 27, 2012, 02:01:36 PM
paul, i got ya beat...the original video i shot?

i had the INPUT to the level control going to the footswitch, rather than the output...so it was looped around backwards.
couldn't figure out what the hell i got wrong til i looked at it hard!!

so....in bypass, it was bypassed thru the volume pot. and wired backwards.

when i figured out i had the bypass wrong, i fixed it...and nuked the pedal, cuz i didn't notice where the output was actually COMING from..now, in bypass, the pedal went dead.
;)

figured it out eventually...forgetting a ground? dude...i do that wayyyyyyyy too often!! ;)
Title: Re: Harmonic Percolator - make one!
Post by: Paul Marossy on October 27, 2012, 05:53:05 PM
That sort of stuff happens to all of us once in a while I guess.
Title: Re: Harmonic Percolator - make one!
Post by: pinkjimiphoton on October 27, 2012, 07:39:01 PM
seems to happen to me on a daily basis!!  :o ::) ;D
Title: Re: Harmonic Percolator - make one!
Post by: effection on October 28, 2012, 04:58:03 PM
Hey! I usually just lurk around here, but I figured I'd jump in and give my two cents on this circuit, some notes and observations, since I've worked on making variants of this for a few years now.

It originally started when a friend of mine was way into the Black Keys and wanted a crazy fuzz tone to do that style stuff. I made him a quick Percolator variant out of whatever I had on hand, and it made for a sweet pedal.

I used a 4403 for the PNP and a 3904 for the NPN. My new Percolator variants use a Russian GT308A. This won over the MP16 (which I found strange, since it's the equivalent to the original 404A, I think) and an AC188 (not surprising, I've learned to hate those things).

For diodes, I use these black OA126 germanium ones that are really awesome. These are best if you're adding a clipping switch with silicon and germanium options, as the forward voltage is about .72-74 on the ones I got, so it can be easily put on a switch with 914's and you don't get the volume drop in comparison like with 1N34a's or similar germaniums.

I took out R6 (consensus schematic). I replaced this with a low-voltage germanium diode like a 1N34a. There are other cool options here like the AMZ warp controls for different clipping effects. This is a pedal that really benefits from that.

A personal touch that really doesn't make that much of a difference is that I put the diodes in the feedback loop of Q2 instead of after. This was honestly because it fit better in my layout. I played around with it, and I couldn't really tell, so it stuck like that. I think this makes it a bit more conventional anyways, a la Big Muff.

I never tried the 1n5 cap from the collector of Q1 to ground, but that honestly makes total sense and is something I should start doing. Before that, I also took note of the Big Muff and put a 470p cap in the feedback loop of Q2 to tame out the high end. (notice how my second gain stage is looking more and more like a Big Muff gain stage?)

I also played with some values, and here is what I seem to like (from consensus schematic):

R1 - 680K                                                                              C1 - 100p
R2 - 220K                                                                              C2 - .022uF
R3 - 100K                                                                              C3 - 1uF
R4 - To taste. Honestly anywhere from 22K-130K                C4 - 22uF
R6 - 1N34a ge diode                                                             C6 - .1uF      
Title: Re: Harmonic Percolator - make one!
Post by: effection on October 28, 2012, 05:18:32 PM
10uF tant sounds pretty good though. Better than a high-end ELNA cap that I tried. But, 10uF has a drawback; doesn't clean up as well as a 47uF when you roll of the volume. I have a 33uF Philips axial in right now, and I think it's the best compromise to date. Good harmonic content, feedback attainable (though higher volume is needed), and cleans up pretty decent.

I get the feeling this thing is telling me to stay between 22 and 47uF.

Why don't you try something like this? Dial in anywhere from 10 to 43

(http://i.imgur.com/6536S.jpg)
Title: Re: Harmonic Percolator - make one!
Post by: pinkjimiphoton on October 28, 2012, 07:20:56 PM
hey, that's a great idea!!
Title: Re: Harmonic Percolator - make one!
Post by: effection on October 28, 2012, 09:11:39 PM
Let me know how it goes. I'm curious if that's a good knob to have on the pedal.
Title: Re: Harmonic Percolator - make one!
Post by: pinkjimiphoton on October 28, 2012, 09:30:01 PM
i may be knocked back for a few days, depending on frankenstorm...  :icon_eek:

 ;D
Title: Re: Harmonic Percolator - make one!
Post by: digi2t on October 28, 2012, 10:15:05 PM
i may be knocked back for a few days, depending on frankenstorm...  :icon_eek:

 ;D

Batten down the hatches, and stay safe bro.
Title: Re: Harmonic Percolator - make one!
Post by: Jazznoise on October 28, 2012, 10:17:45 PM
Hurricane Sandy? I wish they'd make the names a little better. Hurricane Holocaust, or maybe Hurricane Brofist Your House.

I'm boxing my Octavia tomorow. I can't get any Ge Trannies till Monday week, so please keep the information trickling in as that means it'll probably be a month before the thing gets built!  :icon_lol:
Title: Re: Harmonic Percolator - make one!
Post by: effection on October 28, 2012, 10:27:38 PM
1. Frankenstorm is a fantastic name for a pedal.

2. On that mod I drew up, I think maybe a 50k pot would be a good call. If it isn't enough to block the 33uF cap entirely, it may be a 13-43 range. 100k would definitely do it, but the range won't be as fine tuned, i.e not much of an impact at the beginning and then a huge jump in capacitance towards the middle.
Title: Re: Harmonic Percolator - make one!
Post by: pinkjimiphoton on October 29, 2012, 12:30:50 AM
maybe a stacked pot, with a cap on both side, and a smaller, median value in the middle?

yah...FRANKENSTORM!!!

LOL

the gov was on the idiot box, telling people to be careful. truth is, they don't know what the heck is gonna happen..
i mean, a hurricane crossed with a northeaster and some other weirdness?

won't stop my jam i host on tuesdays, unless the power goes out. that's the phattest drag, not being able to indulge my solder addiction..lol
Title: Re: Harmonic Percolator - make one!
Post by: bluebunny on October 29, 2012, 11:34:51 AM
Hey Jimi - hope you weather that storm safely, and all our other friends in those parts.  Stay safe!  And enjoy your Tuesday jam, of course.  ;)
Title: Re: Harmonic Percolator - make one!
Post by: Paul Marossy on October 29, 2012, 11:37:52 AM
won't stop my jam i host on tuesdays, unless the power goes out. that's the phattest drag, not being able to indulge my solder addiction..lol

Hurry, build a few battery powered amps! Or get a small generator.  :icon_wink:
Title: Re: Harmonic Percolator - make one!
Post by: pinkjimiphoton on October 29, 2012, 01:41:18 PM
i gotta ruby amp i built, a box full of 9volt batts, and 7 milkcrates full of pedals to play with, i'm cool, let the power failure commence!! ;)

thanks guys... more worried about oldschoolanalog (dave wiener) cuz he's right where that sh*t is gonna make landfall.

and my kid, about a 10 minute walk to the beach on the coast of southern maine.
Title: Re: Harmonic Percolator - make one!
Post by: pinkjimiphoton on November 14, 2012, 05:51:01 PM
ummm, guys, check out what arph came up with on the "other forum"....

http://..........org/viewtopic.php?f=6&t=20017

hot DAMN!
Title: Re: Harmonic Percolator - make one!
Post by: ~arph on November 15, 2012, 10:46:21 AM
This forum should support attachments too  :-[

Its a harmonic energizer into a harmonic jerkulator.. forcing all the harmonics together in the Harmonic Fusion Engine  ;D

Anyway... since it's my schematic I might as well post it here too... apologies for the size, but it's readable now..

EDIT: and the soundclip:  http://soundcloud.com/arrfx/harmonic-fusion-engine (http://soundcloud.com/arrfx/harmonic-fusion-engine)
(https://dl.dropbox.com/u/1849818/hfe-fixed.png)

It's on dropbox so grab it while it lasts..
Title: Re: Harmonic Percolator - make one!
Post by: pinkjimiphoton on November 15, 2012, 10:57:25 AM
where's the dang "like" button????  :icon_mrgreen:
Title: Re: Harmonic Percolator - make one!
Post by: John Lyons on November 15, 2012, 11:02:33 AM
Sounds great!
Title: Re: Harmonic Percolator - make one!
Post by: ~arph on November 15, 2012, 11:03:14 AM
Yeah it does!
Title: Re: Harmonic Percolator - make one!
Post by: ~arph on November 19, 2012, 03:36:11 PM
Hi all,

Here's a vero I did.. Was going to verify it, but I ran out of solder  :o yikes.

https://dl.dropbox.com/u/1849818/hfe-vero.png (https://dl.dropbox.com/u/1849818/hfe-vero.png)

BIG image
Title: Re: Harmonic Percolator - make one!
Post by: pinkjimiphoton on November 19, 2012, 03:58:33 PM
arph, do you mean 2n3904 or 3404?

i am on this sh*^ like white on rice... ;)
Title: Re: Harmonic Percolator - make one!
Post by: ~arph on November 20, 2012, 01:54:50 AM
You can use whatever transistors you like in a jerkulator. I tried 3906 / 3904 and that sounds great. I settled for a 3404 and a 2907. Btw intended it to fit in a hammond B size enclosure. Might be a little tight.
Title: Re: Harmonic Percolator - make one!
Post by: pinkjimiphoton on November 20, 2012, 10:40:22 AM
sweet! will try and verify it this weekend.. i'm balls to the walls the next few days, gotta clean my workshop (the dining room table) off for the feast of friends on thursday, that'll take a week! ;)
Title: Re: Harmonic Percolator - make one!
Post by: ~arph on November 20, 2012, 10:46:20 AM
Btw, the polarity protection diode is missing from that layout..It'll work without, but it's easy to add (move R19 one place to the left and put it on the rails to the right above it.)
Title: Re: Harmonic Percolator - make one!
Post by: pinkjimiphoton on November 20, 2012, 10:53:26 AM
cool, i'm sloooo oooo ooooo ooooo wly getting hip enough to ad that stuff to everything i build. ;)
Title: Re: Harmonic Percolator - make one!
Post by: ~arph on November 20, 2012, 10:57:16 AM
 ;D

You'll notice it when you put it in backwards
Title: Re: Harmonic Percolator - make one!
Post by: pinkjimiphoton on November 20, 2012, 11:03:36 AM
lol...done that, too...lol
Title: Re: Harmonic Percolator - make one!
Post by: jrod on November 20, 2012, 11:08:59 AM
That sounds really good ~arph!
Title: Re: Harmonic Percolator - make one!
Post by: ~arph on November 20, 2012, 02:06:40 PM
Yeah it's a great circuit. That clip is with a fender hot rod on clean miced up close and a touch of reverb.. I am entering the lab now to try a little noise gate at the end and maybe the stupidly simple wonderful tone control too.. But it's great as is.

-UPDATE-

Back from the shed.. Here's an updated vero with tone control (thanks Jack Orman) and some noise reduction on the two transistors. I added 220pF caps from Base to Collector on both the PNP and NPN, this reduced the hiss a lot, without sacrificing too much of the high end. This is the version I will build as soon as my solder stock is refilled. I am planning a PCB layout for this too. Should fit better in a Hammond B then.

If you don't want the tone control (it is really usefull) then you can omit the tone pot and take the output to the volume from the lug two wire of the tone pot.

https://dl.dropbox.com/u/1849818/hfe-vero-tone.png (https://dl.dropbox.com/u/1849818/hfe-vero-tone.png)
Title: Re: Harmonic Percolator - make one!
Post by: pinkjimiphoton on November 21, 2012, 02:23:03 PM
even better...thanks arph!! soon as i get a chance and get past the wholesale holocaust on our turkeys here, i'm on it!   :icon_twisted:
Title: Re: Harmonic Percolator - make one!
Post by: Mustachio on November 24, 2012, 03:29:19 AM
So now that the turkey day contest is over I can get on this!

While I was waiting for paint and clear coat to dry I started putting this on the bread board. Was trying to follow the vero layouts from jimi and digi. I didn't get it working yet but I didn't have much time to play around with it. I think I am just missing a few connections , ill get it :)

I wanted to ask what  you guys think of these transistors I'd like to use on it. I got these matched pairs of ac128K and ac176K from minifux off ebay a while back and have wanted to find something I could use them in. In the past I used a 2n2222 and an ac176 in an NPN fuzz face which sounds great being half germ and half silicon.

I was going to try to use the 128 and 176 in this circuit since they are supposed to be matched and npn/pnp But I've read a bit around the forum here about ac128's possibly having to high of gains for some things and this circuit sounded like lower gain transistors sounds better. I have about 5 pairs of those and one GT308B on hand. I think the GT308B might have lower gain and lower leakage the 128s might have higher gain and higher leakage and I've heard in some circuits(maybe this one) leaky trannys work better.

Or should I go with silicon/germanium. I was also thinking about how in some fuzz's you will change resistors that feed the transistors to get things correct. Like how small bear will provide resistors with trannys for certain circuits (TB/FF). Will something like that work in this circuit? Ill do all the testing I just wanted to throw out what I had on my mind about this. From the samples Ive heard from Jimi and Digi this sounds like something I gotta play! I love the feedback and scoped tone that brings out the voicing of notes! (also you guys can play a mean guitar!)

The layout arph made looks awesome but I want to build the standard Harmonic perc alone first. I usually have to go over schematics and veros a few times with the eyes and get all the connections right when I bread board off of em. I'm not super sharp with reading all the schems and layouts but I'm getting better the more projects I complete!

Anyway thanks for all the info in this thread I've read through it a few times and will do a few more times. You guys make this stuff a lot of fun!
Title: Re: Harmonic Percolator - make one!
Post by: pinkjimiphoton on November 24, 2012, 05:41:04 PM
ha! i got the same transistor sets. i found 'em all to have too much gain, but your mileage may vary. the high gain transistors may be a sound you like...an intense octave fuzz kinda like a univox superfuzz.

i think you'll like it best with low-gain transistors, but try it... you may be able to bias it up to the point it works for you. ;)
Title: Re: Harmonic Percolator - make one!
Post by: ~arph on November 25, 2012, 03:33:38 AM
I started on the vero, I noticed the following errors in my layout:  C13 must be 22n also and R14 is 27k instead of 1k.. 
Title: Re: Harmonic Percolator - make one!
Post by: pinkjimiphoton on November 25, 2012, 12:14:01 PM
thanks for the heads-up, arph!

no more builds til i'm done with the turkey day scoring tho~~ ;)
Title: Re: Harmonic Percolator - make one!
Post by: ~arph on November 27, 2012, 04:50:02 AM
It's verified  :D

And deserved it's own thread here:

http://www.diystompboxes.com/smfforum/index.php?topic=100164.new#new

Slight alteration to the VERO so it fits in the box. The other vero's posted here should be verfied too.
Title: Re: Harmonic Percolator - make one!
Post by: pinkjimiphoton on November 28, 2012, 02:00:37 PM
sweet, thanks arph...gonna go check the other thread now!
Title: Re: Harmonic Percolator - make one!
Post by: pinkjimiphoton on January 04, 2013, 12:34:38 PM
all germanium percolator... the germonic percolator.

2n2273 ge pnp, hfe 87, and a ac176 ge npn, hfe 100 ish (would change of course depending on temperature.

i'se sick...so bare with me. but you may like it. it's pretty fat when it's loud.

universal old school little less than unity fuzz.  does all the hp tricks, but a little "warmer" for such an obscene thing.

Title: Re: Harmonic Percolator - make one!
Post by: garcho on January 04, 2013, 01:38:32 PM
@Mustachio

Quote
Or should I go with silicon/germanium.

from Small Bear, regarding their 2N404a:
Tested in the George Giblet circuit, gains will run between 55-200 Hfe, leakage under 300 microamps, and low noise floor.

I've only built the Harmonic Percolator straight off the Giblet schematic (on page 3 (http://www.diystompboxes.com/smfforum/index.php?topic=99596.40) of this thread), but it worked like a charm, no fiddling necessary, at least, to my ears. I used 2N404a (165 Hfe), 2N3565 (300hfe), and [EDIT] 1N695 for the semiconductors. Also, did ye olde 100Ohm series resistor and cap PS filter, with reverse polarity protection, and ended up with about 12V from my wall wart. Haven't measured much because it sounded fantastic right off the bat. Regarding the style of distortion, Albini said it perfectly: "More of the good, less of the crap".


@Jimi

drink some OJ, eat some soup, and get some sleep dammit!
Title: Re: Harmonic Percolator - make one!
Post by: pinkjimiphoton on January 04, 2013, 07:00:55 PM
lol.... oj only with tequila

soup til i'm drowning

what, it don't look like i just fell outta bed? 

i made this stupid video, then decided it needed more balls than it needed that nice tone.
went back to whatever npn i'd used originally.

beauty!
Title: Re: Harmonic Percolator - make one!
Post by: Jazznoise on January 10, 2013, 09:33:59 AM
Hello fellas, so I finally built mine but the voltages seem funny.

Q2 and Q1's Rc are both 100K. Q2 = 2N3904, Q1 is a fairly low hfe AC128 (about 30-40, repeated measuring drifts considerably). Power supply is a One Spot at 9.5V.

Q2
E 2.55
B 2
C 2.1

Q1
E 0.17
B 0.25
C 2.1

Is this just because R4 is too large? I haven't plugged it in simply because I can't see a base voltage that low giving me anything. Hoping I don't have to pay for 2n404's, as I can get AC128's for free within small quantities.
Title: Re: Harmonic Percolator - make one!
Post by: pinkjimiphoton on January 10, 2013, 01:13:35 PM
q2's e seems kinda high to me... gonna wait for someone with some intelligence to speak tho. ;)

cuz...i ain't it!!
Title: Re: Harmonic Percolator - make one!
Post by: Jazznoise on January 11, 2013, 11:51:41 AM
Your modesty is as compelling as always, Jimi!   :P

I'm willing to speculate on the Emitter resistor on Q1 being too high or maybe the 220K resistor for Q1's Rbe being too small, but I aint sure!
Title: Re: Harmonic Percolator - make one!
Post by: pinkjimiphoton on January 11, 2013, 12:16:09 PM
 :icon_mrgreen:

what i do lately if i can't figure it out is replace the suspect resistors with pots... or in some cases, use roach clips on wires to put pots in parallel with the suspect resistor,
and twist the pot til it works.

measure the resistance, go with the next standard value that's close.

or, if ya do the trimmer thing, say ya gotta 100k resistor.. if you parallel that with a bigger pot, and use this parallel resistance calculator gizmotron to see what your load is, you can also dial it in. i used it on my toneblaster...100k resistor with 100k trim in parallel.. can dial it in to whatever ya need.

i don't think i'm being clear, sorry, i need coffee bad!!

here's the link...saves my arse daily!!

http://www.sengpielaudio.com/calculator-paralresist.htm
Title: Re: Harmonic Percolator - make one!
Post by: Jazznoise on February 11, 2013, 07:55:33 AM
Bumping this as I've still had no luck in getting the thing working. Figured out my 2N3904 is reversed and now my voltages look WORSE!  I used a 100K for both R3 and R4 and I seem to drop about 8 V just over that 100k. I get that that gives me about 0.08mA of current flow, so should I be trying to lower R3 to allow more current flow? If I parallel a 100K the emitter on Q2 pulls up to about 1.3 volts, about 2 volts with a pair of them. But Q1 still has a huge voltage drop between Vc and Vb

My transistors are the same. Here are the new voltages:

Q2 =  2n3904
E 0.9V
B 0.3V
C 0.3V

Q1= AC128
E 0.18
B 0.3
C 0.3

I've swapped the AC128 for everything, even a 2n3906 and one thing I've discovered is my feedback resistor R2 is showing up as about 6K resistance. Am I just an idiot and is this due Rbe is so small or could this be the cause of the transistor being pulled so low?
Title: Re: Harmonic Percolator - make one!
Post by: duck_arse on February 11, 2013, 09:08:49 AM
jazznoise, how does yours sound?

I breadboarded to the giblet circuit, and couldn't find any transistors that got near the posted voltages. pulled it apart, and then rebuilt it with the geminiIII values, with both Ge. then pulled out the top Ge and put in the oldest, crapest 2n3565 I own. still no voltages right, the top trimmer only seems to make it slightly louder, and the collector bias resistor at 150k makes for shorter sustain, so I'm putting a header there with the 680k.

now I'm going to solder it, and be done with it.
Title: Re: Harmonic Percolator - make one!
Post by: Jazznoise on February 11, 2013, 09:30:47 AM
I'll put it this way, it goes a great rendition of 4' 33''
Title: Re: Harmonic Percolator - make one!
Post by: duck_arse on February 11, 2013, 09:45:37 AM
..... and no-one likes modern music ....

so you get no output at all?

looking at yr voltages, you should have the same on BOTH emitters, whatever it is, because they are connected.

they are connected, aren't they?
Title: Re: Harmonic Percolator - make one!
Post by: Jazznoise on February 11, 2013, 09:57:23 AM
Actually I'm really into some of that stuff. Cage's Piano Sonatas are pretty cool, and I like alot of the Minimalist stuff (though less the phase based music). Peices like I'm Sitting In A Room even are very engaging, once you stop thinking in terms of just harmonic movement.

But this is wildly off topic.

No output. I can touch the Emitter of Q2 and get it to "brrr", but it's actually quieter than when I do it with no power. Weird, eh? The AC path to ground through the circuit is easier than going to my amp.

I'm pretty sure it's to do with the nominal current flowing through the transistor stages and the series feedback on Q1 dragging it down. Not sure what to do about it, though.
Title: Re: Harmonic Percolator - make one!
Post by: pinkjimiphoton on February 11, 2013, 12:52:38 PM
those voltages are way off.
i'll crack mine open when i get a chance and give ya the voltages i have in mine.

looks to me like you're not getting any juice to the circuit.  if memory serves, should be around 5v at the collector.

check your caps, first thing i can think of. somewhere you have an open circuit. is this on a breadboard, or a circuit board jazz?
Title: Re: Harmonic Percolator - make one!
Post by: Jazznoise on February 11, 2013, 01:12:33 PM
I've checked and double checked for shorts, I'd say if I run the scribe again I might snap the thing.  :icon_lol: Once again I can pull the voltage up by lowering the resistor from Vs to Q1, but the Ge transistor just never seems to pull up. That said, I never tried to get it upto 5! Might parallel the 100k with a 10k or something and see if I can't ballpark 5v. Though that might cause other problems...

That'd be great, Jimi! If you could give me your values for R3 and R4 that'd be great, too. There's some trick to biasing this that my brain just doesn't get.

It's soldered onto veroboard. My caps should all be fine. It's a 47uF Axial Electrolytic for the ground cap for Q1 and Q2, ceramics for C1+C3 and a pair of white (Possibly mylar, little square plastic things) caps for C2 and C6. I've no cap meter, but the values all translate correctly from Cap Code jibberish.
Title: Re: Harmonic Percolator - make one!
Post by: garcho on February 11, 2013, 01:39:59 PM
the only thing between both emitters and ground is a single 47uF cap, so they can NOT be at different voltages. unless, of course, something isn't soldered in correctly.  ;)  Did you make your own layout?
Title: Re: Harmonic Percolator - make one!
Post by: Jazznoise on February 11, 2013, 03:41:51 PM
Why must I always confuse the emitter and collector? Seriously considering getting it tatoo'd somewhere on my forearm..

The 0.3V refers to the emitters. I did my own layout as I didn't have the correct resistor value for a 750K so I had to series a 470K with a 300K

UPDATE: Did a little more nosying and found tha R4 was not the value I'd put in. So I scribed the life out of it and my new voltages are:


Q1

E 1.28
B 1.27
C 1.28

Q2

E 1.28v
B 2.71
C 3.28

There are no shorts on Q1, I double checked.
Title: Re: Harmonic Percolator - make one!
Post by: pinkjimiphoton on February 11, 2013, 06:14:01 PM
if it's on veroboard, first thing i suspect is continuity. check every trace, every connection for continuity.

dumb question, but i've done this too many times to count... do you have the board ground hooked up to the starground?
no chassis ground can make all kinds of weird shit happen.

gonna go check mine right now...take a quick walk with me, will ya?


ok...

battery voltage 9.40

q1 (mp16b, russian germ hfe 115 leakage 6ma)
c   5.62
b   5.60
e   3.96

q2  (2n5089) (hfe 626)
c   5.62
b   5.89
e   6.21

but wait, i gotta problem here...

the voltages change depending on the settings of the damn knobs!!
what's above was what i found when i first fired it up.

but looking at it, the 5089 is in backwards. like, flipped 180 degrees from how it SHOULD be, but it SOUNDS BETTER that way!!

wtf.. dude, i gotta play with this some...lol

with the trannys in the PROPER way, it has way less balls...but here's the readings:

q1
c  2.63
b  2.56
e  .69

q2
c  2.63
b  3.15
e  5.76

looks like q2 is backwards, doesn't it? wtf? but my meter says the pinout's right...

here's the readings with q2 wrong:

q1
c   3.74
b   3.62
e   1.01

q2

c   3.74
b   4.16
e   4.36

man..this thing has me thrown for a loop now!! wtf!!

gonna put q2 in backwards, it has way more fuzz and volume.

something weird!!! ;)
Title: Re: Harmonic Percolator - make one!
Post by: Jazznoise on February 11, 2013, 06:49:24 PM
Wow, Jimi! This is very interesting. If what you say is true than the input and output loading makes a big difference. I'll try and test with amp and guitar in future - though I have both pots installed. No shorts, just went line by line again with the DMM. The only think I'm thinking at this stage is some of the caps having a really low ESR - but we're talking values of 200K+. Still, if I turn my knob to 0 I get an audible "bump" type noise. It's not quite DC crackle, but it's weird.

Jacks and PSU are hooked to the same grounding, no chassey ground as of yet. Bit of a catch 22 to go drilling out a box that may never work!
Title: Re: Harmonic Percolator - make one!
Post by: garcho on February 11, 2013, 07:32:45 PM
Post your layout? Might be something a fresh set of eyeballs could notice.
Title: Re: Harmonic Percolator - make one!
Post by: Jazznoise on February 11, 2013, 07:37:51 PM
First thing tomorow night. It must be something weird I didn't spot. Anyway I've college, band practice and Pancake tuesday to tackle in about 7 hours so I'd better get my rest!

Peace!
Title: Re: Harmonic Percolator - make one!
Post by: pinkjimiphoton on February 11, 2013, 07:44:45 PM
on mine also, it's set to short the fuzz to ground in bypass.
but the voltages i posted are what i had...
first set was what it had when i fired it up, with q2 backwards and the knobs set randomly (as in: not set at all)
second set was with trannys "right" and knobs pegged.
third set was with q2 inverted and knobs pegged.

pretty large variance in voltage, huh?

weird circuit!!! really really weird!!
Title: Re: Harmonic Percolator - make one!
Post by: Jazznoise on February 12, 2013, 05:14:32 PM
(https://www.dropbox.com/s/f2cth218r492i3g/Picture%20017.jpg)

(https://www.dropbox.com/s/kj7s2w2pphedclh/Picture%20018.jpg)

The pics aren't great, but they're as reasonably as I can get under artificial light. Behind the 2N3904 is indeed a cap. The two resistors behind that are a 100K and a 680k wired in series for a measured 770K.  Red is input, black is ground, pots are off screen. Vero is sillily oversized because the boxes I have are slatted and thus it's easiest to simply make the board too big and sliiiide it in.

I don't see anything wrong. My solder isn't the most appealing but there's no cold joints or shorts. It's also because I've resolder to test resistors for being deffective (my feedback resistor for the 128 reads 6K in circuit and the standard 250ish out. No short across the base and collector. This pedal is starting to give me a cold joint in the soul!

Any observations or advice recommended. I'd even just take a hug right now!  :icon_lol:
Title: Re: Harmonic Percolator - make one!
Post by: garcho on February 12, 2013, 05:30:02 PM
well, those broken pic links ain't helpin'  ;D

Quote
This pedal is starting to give me a cold joint in the soul!

smoke a cold joint and don't beat yourself up
Title: Re: Harmonic Percolator - make one!
Post by: Jazznoise on February 12, 2013, 05:36:24 PM
You win again, dropbox

https://www.dropbox.com/s/kj7s2w2pphedclh/Picture%20018.jpg

https://www.dropbox.com/s/f2cth218r492i3g/Picture%20017.jpg

A hot shower beats a cold joint any day!  ;)
Title: Re: Harmonic Percolator - make one!
Post by: duck_arse on February 13, 2013, 09:32:11 AM
I've taken my circuit off the breadboard for an octavia, but that's a different story. my perko voltages were so far off that I was too ashamed to write them on the circuit.

every single time I put this on the breadboard, I'd get the transistors around wrong because of the weird circuit. like pink, I had it going backwards, and looking interesting on the cro (if difficult to drive), but then reboarded it, and did it proper.

I'd suggest you breadboard it with different parts if you can, see what you get then.

and the "20017" page only gives error
Title: Re: Harmonic Percolator - make one!
Post by: pinkjimiphoton on February 13, 2013, 02:22:04 PM
this circuit is just plain weird.
i reccomend just getting it to work, and do whatever ya gotta do to make it sound good! ;)
Title: Re: Harmonic Percolator - make one!
Post by: Jazznoise on February 13, 2013, 04:36:18 PM
Fixed that link.

It is definitely beyond weird. Looking at the caps I've used I'm wondering if the two little white fellows aren't giving me undue greif. If no one spots an unprecedented level of stupidity by yours truly I think I may have to shelve this until the end of the academic year. :icon_confused:
Title: Re: Harmonic Percolator - make one!
Post by: pinkjimiphoton on February 13, 2013, 06:41:06 PM
try replacing the cap, maybe.
is q2 the right way? i've made the mistake more times than i can count.
and on mine, having that transistor backwards yields a completely different animal
Title: Re: Harmonic Percolator - make one!
Post by: Jazznoise on February 13, 2013, 06:58:18 PM
I've re-orientated them both. All 4 permutations are equally noiseless and miserable.

I agree, Jimi, I'm thinking swapping them might be a good port of call. The DC values don't seem unreasonable, but it's the inability to pass audio that makes me think the AC impedance must be totaly messed up.
Title: Re: Harmonic Percolator - make one!
Post by: pinkjimiphoton on February 13, 2013, 09:49:56 PM
i've had a few builds laid low by bad caps or resistors, i mean brand new ones.
i've noticed particularly on "standing up" components, sometimes they look fine but are "decapitated" internally.
so far almost every circuit i've had trouble with, it came down to one side of a resistor being broken off (but still looking connected) or bad electros that just plain don't @#$%ing work.
don't give up!!
fwiw, if ya have to, build the jerkulator tim escobedo drew up, it sounds pretty much the same as the perc does.
and it's WAY easy.
Title: Re: Harmonic Percolator - make one!
Post by: garcho on February 14, 2013, 03:10:50 AM
Do you etch PCBs? I can give you a layout if you'd like. There's got to be a number of them already online. Ferric chloride isn't expensive, and a little PNP blue paper can go a long way. Worth looking into anyway (http://www.smallbearelec.com/servlet/Detail?no=600).
Have you checked out any of the layouts made by DIYSB forumites? A lot of people around here have built it with much success, and I'm sure many of them have done it with vero/perf. Have you compared your layout to anyone else's? I misread the schematic the first time I tried to breadboard the Percolator, and realized it when I looked at someone's PCB.
Title: Re: Harmonic Percolator - make one!
Post by: duck_arse on February 15, 2013, 09:02:46 AM
yr board's way too big. you should always use the smallest, meanest bit of vero you have, just to make everything easier.

I never use sockets. have you thought of them being the problem?
Title: Re: Harmonic Percolator - make one!
Post by: garcho on February 15, 2013, 12:35:01 PM
Quote
I never use sockets. have you thought of them being the problem?

what kind of problems have you had with sockets? I've never had any myself.

Germanium transistors don't like too much heat, be real careful if you're not using a socket.

Title: Re: Harmonic Percolator - make one!
Post by: pinkjimiphoton on February 15, 2013, 07:00:06 PM
sip sockets like most people use imho are a pain in the ....

i get 6 pin ic sockets, and dremel them in half.
the prob with sip sockets is once you use them a couple times, they don't grip very well.

a tip from dave w. is to use them to find the trannys ya want, then CAREFULLY squeeze them just enough to crack the plastic, then solder the transistor to the sockets.

the ic sockets tho  seem to be a bit more robust usually.
Title: Re: Harmonic Percolator - make one!
Post by: duck_arse on February 17, 2013, 08:40:39 AM
Quote
what kind of problems have you had with sockets? I've never had any myself.

that's the trick. I've never used them, so I've never had a problem with them. sort it out on the breadboard (or stick in a switch).
Title: Re: Harmonic Percolator - make one!
Post by: Jazznoise on February 17, 2013, 08:50:42 AM
I hear you on the big board, but it's mostly unused space to make the mounting of the board easier.

No detectable shorts and the socks are fine - everything reads as it should under the gaze of my watchful DMM. I'm the same as Jimi, I take DIP sockets and I cut them up with my snips. Just never saw the neccesity of buying SIP sockets.
Title: Re: Harmonic Percolator - make one!
Post by: duck_arse on February 17, 2013, 09:36:14 AM
any sign of output yet?
Title: Re: Harmonic Percolator - make one!
Post by: duck_arse on February 19, 2013, 09:05:51 AM
so I wired up my perko in its jig, works first go. the value of diagrams, eh? anyway, now it's built, I'd better add my "harmonic percolator voltages" to the pot ....

using (q1) 2sb156 hFE=43 leak=100uA, Rc1=22k, Rb1=220k, (q2) 2n3565 hFE=290 (maybe), Rc2=22k + 50k trim, Rb2=150k/680k, V+=9V11, I get:

with Rb2=150k -- Vc1= 1V88 ~ 3V79 -- Vb1= 1V85 ~ 3V80
     Ve= 2V08 ~ 4V48
     Vc2= 2V79 ~ 5V31 -- Vb2= 2V61 ~ 5V01

and with Rb2=680k -- Vc1= 1V78 ~ 3V48 -- Vb1= 1V70 ~ 3V13
    Ve= 1V95 ~ 4V09
    Vc2= 3V13 ~ 5V62 -- Vb2= 2V45 ~ 4V51

(the 150k Rb2 is mounted on a header, for user selectable long or short sustain. user can also decide their own bias preference.)

with my resistor values different to everyone else's, my voltages are not surprisingly different to everyone else's. to my ears, the clipping diodes are masking any differences the biasing might produce, except for an increase in volume as the Vc2 gets near V+/2.

which doesn't look right, because the diodes will keep clipping at the same level, no? must be one of those "things" that sounds like more volume, but isn't. anyone have a word for that apparent volume increase besides volume?

now to hammer it into that bloody salad bowl .....
Title: Re: Harmonic Percolator - make one!
Post by: LucifersTrip on February 23, 2013, 04:22:34 AM

I used a 2N3565 (hfe around 150) and a 2SB33 (hfe 52-54)

The voltages, however, are as follows (battery = 9.7V):

Q1: E-1.58  B-1.49  C-1.39

Q2: E-1.58  B-2.12  C-3.24   


Finally breadboarded and my voltages are very close to Mark's

Q1 (GE 100 hfe / 50uA leak)
Q2 (SI 100 hfe)

9.69V supply

E        B       C
1.71,  1.60,  1.43
1.71,  2.39,  3.24

Sounds good, but not nearly good enough to finalize...time to experiment. There seems to be a sh*tload of possible hfe combos.

Title: Re: Harmonic Percolator - make one!
Post by: hellwood on March 10, 2013, 03:41:36 PM
for those of you less than impressed with this circuit, dig through your junk drawers for your leakiest dud transistors before you give up. Germanium for Q2 makes all the difference too...I was seriously about to scrap this thing after what I thought was an entire day wasted experimenting. Now I cant stop playing with it.

Q1 2n404 (610 hFE/6.1 leakage)
c 1.60
b 1.68
e 1.8

Q2 2n1302 (125 hFE/1.25 leakage)
c 1.88
b 1.86
e 1.81
Title: Re: Harmonic Percolator - make one!
Post by: pinkjimiphoton on March 10, 2013, 10:27:46 PM
i messed around with mine some, too.
i got it sounding great, but it wasn't quite unity gain.
i was like...wtf!!
so i said screw it, and went with all silicon... and found the sound i heard in the albini demo.
tho, to be fair, the sound he gets in that is NOT just the perc, it's got a fuzz in front of it.
i can tell, cuz i got the sounds pretty much identical by putting the escobedo jerkulator in front of it..
very cool... almost an octave, sometimes with octave down, too (in some ranges) and almost a 5th harmonic, too.
pretty savage.

my advice? socket... and just stuff in transistors until it make ya feel a little wiggle "down there".
Title: Re: Harmonic Percolator - make one!
Post by: effection on March 22, 2013, 01:17:59 PM
I don't know about when he's recording, but when I saw Shellac, the only thing he had was the Percolator and an MXR Noise Gate. He's more likely using it in front of the IVP's distortion circuit instead of a fuzz in front of the Percolator.
Title: Re: Harmonic Percolator - make one!
Post by: midwayfair on March 22, 2013, 01:57:22 PM
i got it sounding great, but it wasn't quite unity gain.

Huh.

Really?

Mine is insanely loud, and the transistors I used are not particularly high gain. It's at unity with the controls both at noon on the 1N695 side. On the OA126 side, unity is more like 10:00. Of course, mine is less fuzzy than others', so maybe it was just the different resistor values I used. :/
Title: Re: Harmonic Percolator - make one!
Post by: pinkjimiphoton on March 23, 2013, 11:49:40 AM
i tried all kinds of transistors, and in the end, went 100% silicon.
mine was just barely unity gain pegged, now it's at unity around 12:00.
Title: Re: Harmonic Percolator - make one!
Post by: garcho on March 23, 2013, 01:11:46 PM
I used all the components and values as the G Giblet schemo (used a film instead of a ceramic though, and electro instead of tant), with transistors from Small Bear. Definitely full on distortion, sounds great, and loud. Anyone hear the new versions? 300 bucks on Amazon, a little steep. I wonder how they sound? How accurate can the Albini video be if it's on youtube, on video, on your computer, etc.? Adds to the legend, I guess. Albini must be shocked that after spending a decade making underground, loud, noisy, harsh rock and roll that was never radio friendly, now (as in last 20 years) armies of dudes want the very same gear. Is it because of Big Black or Electrical Audio, or just because he produced Nirvana and the Pixies? All part of a grand Interfax marketing conspiracy ;)
Title: Re: Harmonic Percolator - make one!
Post by: hellwood on March 23, 2013, 06:06:30 PM
for those of you less than impressed with this circuit, dig through your junk drawers for your leakiest dud transistors before you give up. Germanium for Q2 makes all the difference too...I was seriously about to scrap this thing after what I thought was an entire day wasted experimenting. Now I cant stop playing with it.

Q1 2n404 (610 hFE/6.1 leakage)
c 1.60
b 1.68
e 1.8

Q2 2n1302 (125 hFE/1.25 leakage)
c 1.88
b 1.86
e 1.81

EDIT:
I dont know how I blew it so bad and posted the wrong voltages, but these are the correct ones:

Q1 2n404 (610 hFE/6.1 leakage)
c 1.62
b 1.73
e 1.86

Q2 2n1302 (125 hFE/1.25 leakage)
c 1.93
b 1.62
e 1.85

also, this thing is LOUD with no lack of fuzz even with the leakiest Germanium transistors I could find in my reject stash. I also tried the 1n34A's and they were lifeless compared to the germanium transistors that I substituted for diodes. weird, but the clippers are obviously night and day critical for the warm and fat fuzz ...still waiting for some 1n695's. I would be interested to hear what others think of  experimenting with their leaky junk
Title: Re: Harmonic Percolator - make one!
Post by: pinkjimiphoton on March 23, 2013, 06:19:24 PM
i revisited this circuit again today too, figured i'd try some of the low gain ge russkies i just got in the mail..
tried a bunch of pos mp25b tophats, i bought 95 of 'em on the bay... 45 have arrived so far, and out of them, 20 read around 40-52 hfe. one read 80. i tried that in the perc.

didn't do it. tried ac128's...same deal. often, they sounded better turned around 180 degrees (the real leaky ones work better backwards, i think!!)

the mp25's didn't do it.

a 3906 in q1 and a mpsa13 in q2 was pretty good... all si, 300/950 hfe.

then i tried some nos JAN 2n2273/cgg7423p wb's i found recently at a surplus electronics place for a fair price... like a quarter a piece.
bingo...no, BINGO!!!

popped the first one i pulled out of the bag, and wango, that was it. about 45hfe with about 10ma leakage. perfect. could dial in some great tone from my guitar, from sparkly clean to full on fuzz with an almost octavia like bloom in the harmonics. at some settings of the guitar knobs, an octave down appears at some ranges.. it's faint, but it's there.

completely different animal.

300 bux on ebay?

i can beat that price... lol... :icon_twisted:

so i concur... them leaky rotten low gain ge's seem to do the trick.

i tried it all ge, but i preferred the silicon in q2. it's loud its rude, but man, what a cool tone.. some transitors sound ok, but kinda sputtery.
but the right ones man, it's the most fun you can have with your pants on! ;)

i played this thing for 3 hours today. drove my family nuts. they won't talk to me, lol... but that's ok, cuz now i can build something new undisturbed.

 :icon_mrgreen:
Title: Re: Harmonic Percolator - make one!
Post by: garcho on March 23, 2013, 08:00:19 PM
Quote
i played this thing for 3 hours today. drove my family nuts. they won't talk to me, lol... but that's ok, cuz now i can build something new undisturbed.

like a true addict
Title: Re: Harmonic Percolator - make one!
Post by: andrewgf on March 23, 2013, 08:01:52 PM
I built one of these on breadboard and it's awesome.  I also built the harmonic fusion part on to it and found it sounded like a wah used as a filter.  It was interesting hearing the different harmonics that it brought out, but when I finally box it up, I think I'm just gonna build the percolator with only a volume knob.  Mine sounds best at full gain, using the volume knob on the guitar to clean it up if needed.  Put it into another low to med gain distortion it gets HEAVY.  I'm still fairly new to all this, though, and was wondering where I might be able to find alternate transistors to try out.  I just used a 2N404A and a 2N3565 from Small Bear.  
Title: Re: Harmonic Percolator - make one!
Post by: garcho on March 23, 2013, 08:06:58 PM
Check out Harmonic Jerkulator (https://www.google.com/search?q=%22harmonic+jerkulator%22&aq=f&oq=%22harmonic+jerkulator%22&aqs=chrome.0.57j0.7348&sourceid=chrome&ie=UTF-8), by DIY titan Tim Escobedo. I never could get it to sound that good, probably user error.  ::)
Title: Re: Harmonic Percolator - make one!
Post by: pinkjimiphoton on March 23, 2013, 08:27:30 PM
the jerkulator is pretty close! add a diode clipper to it...i did with mine. i like a jerk driving my perc!! ;)
Title: Re: Harmonic Percolator - make one!
Post by: andrewgf on March 24, 2013, 04:29:15 PM
I'm going to build the jerkulator tonight and see how different it sounds.  I started with the "Albini" schematic from Madbean, but have subbed so many different parts I don't even remember what I've got in there now.  For the clipping diodes, I currently have a 4.7k resistor and a 1N34A on one side and a 1N34A and 1N914 on the other.
Title: Re: Harmonic Percolator - make one!
Post by: pinkjimiphoton on March 24, 2013, 06:25:33 PM
why the resistor with the 1n34?

the jerk is pretty close, once ya add the clipper. mostly it all comes down to the transistors imho.
Title: Re: Harmonic Percolator - make one!
Post by: garcho on March 24, 2013, 09:18:19 PM
why the resistor with the 1n34?

It alters the clipping on half the waveform, thereby altering the harmonics. Some other diode-clipping pedals do that.
Title: Re: Harmonic Percolator - make one!
Post by: effection on April 01, 2013, 10:39:23 AM
I'm going to build the jerkulator tonight and see how different it sounds.  I started with the "Albini" schematic from Madbean, but have subbed so many different parts I don't even remember what I've got in there now.  For the clipping diodes, I currently have a 4.7k resistor and a 1N34A on one side and a 1N34A and 1N914 on the other.

Wow, that's a huge difference in the clipping sides. How is that working out?
Title: Re: Harmonic Percolator - make one!
Post by: andrewgf on April 01, 2013, 12:13:12 PM
It has an interesting sort of compression to it.  It sounds pretty good.  I recorded samples of both the percolator and jerkulator with different clipping diode combos, and plan to go through and listen to them and pick my favorite two settings and put them on an on-off-on switch.  Looking at the waveform in my DAW, the series resistor with one diode clips the positive side quite a bit, leaving more dynamic range on the negative side.
Title: Re: Harmonic Percolator - make one!
Post by: garcho on April 01, 2013, 01:00:01 PM
Quote
Looking at the waveform in my DAW, the series resistor with one diode clips the positive side quite a bit, leaving more dynamic range on the negative side.

Yeah, positive or negative depends on the polarity and orientation of the diodes. But that's just how we conceptualize it, negative and positive sounds the same so it shouldn't matter which diode is in series with the resistor.
Title: Re: Harmonic Percolator - make one!
Post by: pinkjimiphoton on April 02, 2013, 12:10:30 AM
i was curious about diode clippers and did a little research...
you can tell which side of the wave is clipped by the orientation of the cathode of the diodes.
if the cathode (bar) faces down, it clips the top of the wave, if it faces up, it clips the bottom.
so you can use asymetrical techniques to clip the treble and bass completely differently..
say, led for more buzz in the lows, ge for sweeter highs.

god, i hope i didn't get that backwards!! ;)
Title: Re: Harmonic Percolator - make one!
Post by: effection on April 02, 2013, 12:18:40 AM
It doesn't work like that. Top and bottom of a sound wave isn't treble and bass.
Title: Re: Harmonic Percolator - make one!
Post by: pinkjimiphoton on April 02, 2013, 12:30:36 AM
ummm... you sure?
if you look at how they work, on the waveform of an oscope, it indeed will work on the top or bottom...or both... of a sine wave.
if you clip the top of the wave, you clip the highs of the wave. if you clip the bottom, you clip the bass content. if you clip both, the highs AND lows will be distorted. that's why some dirt pedals sound better with just one diode clipping instead of the two you usually see (orange boss distortion comes to mind)
i may indeed be wrong, but after doing audio stuff for a couple decades, and looking at too many waveforms in my daw,
i'm pretty sure it indeed DOES work that way.
you can look at it, and see the way it sounds, if that makes any sense.
Title: Re: Harmonic Percolator - make one!
Post by: pinkjimiphoton on April 02, 2013, 12:32:30 AM
maybe i am being obtuse..
when i say bass and treble, i was talking about the top or bottom of the waveform. i think the nomenclature i used was wrong, mah bad!
Title: Re: Harmonic Percolator - make one!
Post by: garcho on April 02, 2013, 02:45:16 AM
Bass is low frequency, not negative polarity. They're not connected in any way.
Title: Re: Harmonic Percolator - make one!
Post by: Kesh on June 04, 2013, 03:17:31 PM
Finally built one. 2n404, and some NPN in a matching top hat whose number escapes me. Standard consensus spec. Sounds great. Pretty dirty. Or pretty AND dirty.

Amusing pic (with a Green Russian BMP)

(http://i47.photobucket.com/albums/f175/hobkesh/comedyfuzz_zpsab85cb89.jpg)
Title: Re: Harmonic Percolator - make one!
Post by: pinkjimiphoton on June 04, 2013, 04:02:39 PM
love the enclosures!!   :icon_mrgreen:
Title: Re: Harmonic Percolator - make one!
Post by: Henry89789 on June 04, 2013, 09:09:37 PM
Yet another pedal I want to build.

Pink Jimi:  I went to Midwest Surplus Electronics .... I got some of those 2n2273 you mentioned and some NPN Si that I hope will include some 100-120 hfe. Let's see .... Thanks for turning us on to that supplier.
Title: Re: Harmonic Percolator - make one!
Post by: pinkjimiphoton on June 04, 2013, 09:33:15 PM
my pleasure brother! hope they work for ya... did ya buy the rest of 'em? i bought like, 50 of 'em i think... ;)
Title: Re: Harmonic Percolator - make one!
Post by: Henry89789 on June 04, 2013, 10:05:30 PM
No. I only bought 20. It seems that on every batch of germaniums that I have bought the HFEs are always advertised as being much higher than they turn out to be. How many 100 hfe and higher did you get out of the 50?  I think I am going to start a thread asking suggestions on what can be done with the lower HFE germaniums; What can be done with them in regard to building pedals that is.
Title: Re: Harmonic Percolator - make one!
Post by: pinkjimiphoton on June 04, 2013, 10:09:41 PM
ha! 100!! lol!!!!!!!

maybe 40-70 in a couple cases. a whole bunch of 16-30 hfe.

BUT... you can bootstrap 'em or something for more gain... basically i think ya make a darlington pair out of 2 of 'em.

not sure of the deets, but hopefully someone who's not a hack like me can explain it bro. ;)
Title: Re: Harmonic Percolator - make one!
Post by: duck_arse on June 05, 2013, 11:28:42 AM
ah-hah! I've finally got my perko to the photo showing stage, but in the picture thread.

now we just got to get jazznoise up and running.
Title: Re: Harmonic Percolator - make one!
Post by: Jazznoise on June 05, 2013, 01:00:48 PM
ah-hah! I've finally got my perko to the photo showing stage, but in the picture thread.

now we just got to get jazznoise up and running.

Yes we do.

There's a board meeting tomorow to determine wether or not I get an I Grade for being sick the last few months. (Had an endoscopy the day before my 21st birthday party  :icon_rolleyes:). If I get the go head I'll be diving back into this and heating up my iron.

Speaking of which, it's f*cking warm in Ireland today. Strange times
Title: Re: Harmonic Percolator - make one!
Post by: pinkjimiphoton on June 05, 2013, 04:38:08 PM
chris... hope all is good man... healing vibes and mega mojo to you my friend!!!!
Title: Re: Harmonic Percolator - make one!
Post by: Jazznoise on June 05, 2013, 05:27:50 PM
chris... hope all is good man... healing vibes and mega mojo to you my friend!!!!

Thanks Jimi! It'll be fine, just this build list is getting ridiculous!  :icon_eek:
Title: Re: Harmonic Percolator - make one!
Post by: garcho on June 06, 2013, 04:02:02 PM
I love this thing, can't stop playing through it. I socketed the diodes and have been noodling with those, but I've discovered I like it best without any. It drives my amps nicely. Such a lovely dirt.

(http://farm6.staticflickr.com/5441/8837728602_ec064dc9b0_c.jpg)
Title: Re: Harmonic Percolator - make one!
Post by: pinkjimiphoton on June 06, 2013, 05:10:19 PM
nice!  without diodes is like te's jerkulator. i really like it. clippage!!!! clippage,, suh!!!!  :icon_mrgreen:
Title: Re: Harmonic Percolator - make one!
Post by: pinkjimiphoton on July 26, 2013, 11:13:52 AM
guys, i came up with a simple mod or two for the perc, i was gonna be a bogart but decided to share.  :icon_mrgreen:

first up, the 91k resistor from the pnp's c to ground... change it to this:

pnp c >  39k resistor > top side of 50k linear pot > wiper of pot > 15k resistor > ground.  you still have the original 91k, but a useable range to dial in harmonics, sustain and grit.

i call it the "focus" mod. it lets you dial in the distortion, and compression, and it DOES behave like a percolator, if your guitar is turned down some, it will swell into single notes like a
percolator perking. it is cool as hell.

next, the "boo-tweak mod" i call it...
second mod, replace  the 750k feedback resistor between b and c of npn with a 470k resistor going into a 500k trimmer wired as a variable resistor. you can fine tune the output and response of the npn section, make the whole pedal a bit louder, and really dial in the tone.  you may wanna just mount a 500k pot on the top of the box and label it "tweak"

seriously... try this out. stupid pedal trick imminent, and oh well, there' goes the first potential entry for the contest!!! lol

now i gotta come up with something else.... but i wanted to share my lummoxed discovery with the brethren and sister....thren... :icon_eek:

but i had to hip you guys to this. it's a great and useful mod.
Title: Re: Harmonic Percolator - make one!
Post by: petey twofinger on July 26, 2013, 08:09:25 PM
steve alibini / harmonic percolator parody :

http://youtu.be/cEfNlWrakRE
Title: Re: Harmonic Percolator - make one!
Post by: pinkjimiphoton on July 26, 2013, 08:18:02 PM
steve alibini / harmonic percolator parody :

http://youtu.be/cEfNlWrakRE

bwah!!!
Title: Re: Harmonic Percolator - make one!
Post by: inductor on July 26, 2013, 10:37:45 PM

first up, the 91k resistor from the pnp's c to ground... change it to this:

pnp c >  39k resistor > top side of 50k linear pot > wiper of pot > 15k resistor > ground.  you still have the original 91k, but a useable range to dial in harmonics, sustain and grit.

i call it the "focus" mod. it lets you dial in the distortion, and compression, and it DOES behave like a percolator, if your guitar is turned down some, it will swell into single notes like a
percolator perking. it is cool as hell.
That's interesting. I'll have to try it...

next, the "boo-tweak mod" i call it...



I raised this to the equivalent of 1.4Meg with a 2n3904 as the npn.
Title: Re: Harmonic Percolator - make one!
Post by: pinkjimiphoton on July 27, 2013, 12:36:24 AM
hey, welcome, inductor!

cool, yah, i could see that working. i didn't try going bigger than 1m on it cuz originally i just wanted to do what tim escobedo did... use common values. 1 meg is close enough for rocknroll with 750k, but the pot thing is hip, you can dial in the output and response of the pedal, make it a little louder if need be, or give it more sustain. too high and it doesn't sing, but get it in the right range and it dilates and swells... it's hip.

so... the focus mod... now forth forever to be known as the "damn stinkin' percolator" knob... use these values.

from collector of pnp (ge gain around 51 or so) replace 91k resistor with  a 47k resistor to the top lug of a 50k pot, linear, and put a 47r resistor from wiper to ground.
if you go lower than that, it starts to lose volume.

that lets you dial it in, and increase the gain from the stock percolator circuit. you can turn the percolator control down and have the classic percolator sound, or turn it up and dial up the harmonics and distortion. parallel octave up/downs. crazy shit. feedback chords.  insane.

and if ya turn it down and dial back your guitar knobs, it can clean up into an almost accoustic kinda sound.

this thing is hip. ;)

i know, i know...video or it never happened.

well... maybe soon, i have to program a jmp1 tomorrow for the other guitarist in my country band so it's ready to go for a humondo benefit sunday... 10 bands in 7 hours, 40 minutes a piece on 2 stages, in which i play with three of the bands not including the house... ayyyyyy my brain hurts... but for a good cause. raffling off a telecaster signed by all the participants, an autographed frank zappa album, a bottle of patron, a case of wine, some handmade jewelry... and maybe a fuzz or two.

so.. bear with me. ;)
Title: Re: Harmonic Percolator - make one!
Post by: Mustachio on July 27, 2013, 07:42:33 AM
Petey holy molly I was dying man omg ! Crazy Hilarious !

So I need to revisit this as well, And since I'm in the mood of drawing new pcb layouts from schems I'm gonna give it a try with what I find in this thread. Gonna try to go off Marks values and try some of the Jimi mods :D Ill let you guys know how it turns out!
Title: Re: Harmonic Percolator - make one!
Post by: pinkjimiphoton on July 27, 2013, 11:35:16 AM
"it's cwazy... the whole thing is cwazy... but it's not as good as the ORIGINAL Libral Komrad...that thing was cwazy..."


dude... that should go down in the anals of diy history as the best parody , like, evah...


sadly, the original liberal komrade gave it's life in the studio fire to the fuzz gods, never to be seen again. snif... :icon_cry:
Title: Re: Harmonic Percolator - make one!
Post by: Morocotopo on July 27, 2013, 12:23:11 PM
Guys, one question:

My percolator sounds niiiice, octave in the 5th string, all is well.

But....

Itīs by far the noisiest OD/dist/fuzz I have. Makes hum, buzz, hiss, all sorts of noises. Not unusable, but would be nice to have it behave more like itīs pedalboard mates. When I compare it to a Guvnor or a Zendrive, it makes them look like they are studio quiet!

Whatīs your experience on that subject?
Title: Re: Harmonic Percolator - make one!
Post by: pinkjimiphoton on July 27, 2013, 03:11:44 PM
they are noisy as @#$%, power supply filter addition helps, but not much. keep your leads wicked short, use shielded cable to/from the switch, and make a sacrifixe to the mexican radio gods and hope for the best.
Title: Re: Harmonic Percolator - make one!
Post by: inductor on July 29, 2013, 11:51:17 AM
hey, welcome, inductor!

cool, yah, i could see that working. i didn't try going bigger than 1m on it cuz originally i just wanted to do what tim escobedo did... use common values. 1 meg is close enough for rocknroll with 750k, but the pot thing is hip, you can dial in the output and response of the pedal, make it a little louder if need be, or give it more sustain. too high and it doesn't sing, but get it in the right range and it dilates and swells... it's hip.


~1.4Meg was the sweet spot when I was tweaking my build. It only adds an extra resistor, so imo it's no big deal. I think I posted my schematic in this thread awhile back...

Also try out the Focus "damn stinkin' percolator" mod with a 1n5 cap to ground from either the collector or the wiper. The 1n5 cap was in the Pussy Fuzz that Mr. Bill made for Steve.

Title: Re: Harmonic Percolator - make one!
Post by: inductor on July 29, 2013, 11:56:17 AM

Itīs by far the noisiest OD/dist/fuzz I have. Makes hum, buzz, hiss, all sorts of noises. Not unusable, but would be nice to have it behave more like itīs pedalboard mates. When I compare it to a Guvnor or a Zendrive, it makes them look like they are studio quiet!

Whatīs your experience on that subject?

Every time I've built a HP1 and it's unusably noisy its because there are grounding issues or interference from long unshielded leads.
Title: Re: Harmonic Percolator - make one!
Post by: Digital Larry on July 30, 2013, 11:14:16 AM
This circuit is fascinating.  While some people have described it as a cascode configuration I do not agree.  I tried to figure out the DC bias conditions of the transistors and as far as I can tell they are biased "OFF" - barring leakage. 

Now the interesting thing is what happens when signal comes in.  But I haven't had the time to figure it out.  Steve Albini's video explanation (cough) of it putting out 2nd harmonic, or, err.. even harmonics, or... uhhh.... whatever leads me to believe it does some type of full wave rectification.  Then some other posters indicated it occasionally puts out an octave down and I am at a total loss for how that would be possible.

Anyone?

 :)
Title: Re: Harmonic Percolator - make one!
Post by: pinkjimiphoton on July 30, 2013, 12:50:24 PM
i think it's soft clipping the signal with the transistors, and using some kinda SCARY PHASEING MAGIC i totally DON'T UNDERSTAND to make it do all this!

seriously, i think something about the circuit seems to  cancel dissonant harmonics.

i can get octaves out of it now...easily. up. down. both. it's insane.  no idea how/why it works. also discovered adding power supply filtering seems to affect it adversely!!

the latest is the best sounding one... if you make that 91k resistor a 47k from the collector of the pnp to the top lug of a 50k pot, and tie the wiper of that to a 47r resistor, you will get ALL the shit in albini's video. seriously.

it's bizzarre. you can make feedback come out in harmonic chords some times.

it's crazy man, like really crazy how ccrazy this crazy thing really is..

once my girl gets up, i will try and shoot some video. that 91k is the main key to percolation. the other is the 1m feedback resistor on the npn.
Title: Re: Harmonic Percolator - make one!
Post by: Digital Larry on July 30, 2013, 01:05:25 PM
OK I wait with (fish) baited breath for the video  :icon_confused:

Other questions:

How does it handle a sustained note?
Volume knob manipulations?

I kinda want to know if it "cleans up" at lower levels or sputters, or... recites the Prime Directive?   :icon_question:
Title: Re: Harmonic Percolator - make one!
Post by: garcho on July 30, 2013, 01:19:52 PM
I thought it was basically some type of push-pull amp. Does that point you in the right direction, or did you figure that out already?  :D

Everyone's gotta hate on Albini. Did he ever say, "Hey DIY community, I'm a professional electrical engineer and I'm going to give you a dissertation on my definitive explanation of a goddamn distortion pedal and do all your homework for you because I'm a genius"? Compared to every awful pedal demo online, including EHX, Gearputz, Harmony Central et al., how could this one draw such ire? Because he has a sense of humor as opposed to the classic rock obsessed virtuoso worshiping bedroom shredders who take themselves and their misinformed explanations too seriously? I know the fanboys get sickening, but now y'all know how I feel about Clapton, Wooten, Colaiuta, etc. Rant over.


EDIT: totally stupid of me to rant, sorry y'all. guess i had a computer chip on my shoulder.
Title: Re: Harmonic Percolator - make one!
Post by: pinkjimiphoton on July 30, 2013, 02:25:03 PM
go, garcho... sorry gary, petey's video has still got me chuckling, i see a lot of guys i know in that..

yes, they sustain ok. it's not like a big muff tho.

volume changes depend on the transistors and biasing. lower gain pnp's seem to clean up a bit more, but never get super clean.

it's hard to describe. gineen's up, so once she gets up and about, i'll make a little noise, but jesus, ya may as well build one, pretty much any pnp and npn combo will work, and the values aren't all that critical in the couple passives in the circuit. wide open door for experimentation.
Title: Re: Harmonic Percolator - make one!
Post by: garcho on July 30, 2013, 02:39:29 PM
I was referring to the over all vibe, not Petey's video or anything specifically, just don't understand the 'mentality' around the gear-web. No need to be sorry!

Larry, take Mark Hammer's advice: build one! Even if you get the mojo parts from Small Bear (I did, and I'm happy I did) this puppy won't set you back much, so no point wondering. I have PCB etch files if you want.
Title: Re: Harmonic Percolator - make one!
Post by: tca on July 30, 2013, 03:14:53 PM
I thought it was basically some type of push-pull amp. Does that point you in the right direction, or did you figure that out already?  :D
Some answers here: http://www.diystompboxes.com/smfforum/index.php?topic=99785.0

Cheers.
Title: Re: Harmonic Percolator - make one!
Post by: Digital Larry on July 31, 2013, 01:31:29 AM
I thought it was basically some type of push-pull amp. Does that point you in the right direction, or did you figure that out already?  :D

Well, it kinda LOOKS like a push pull amp, but those attach the load to the output where the two emitters join together and don't have resistors in the collector circuits.  This has a big capacitor where the emitters join and has resistors in both collector circuits.  Also a push pull amp would drive the bases of both transistors together.  But the top transistor is being driven from the lower one's collector signal!

I've been doing some LTSPICE simulations on it.  I'm not sure I've gotten to the point I want to embarrass myself trying to explain it in detail.  It looks like it creates two pulses per cycle of the input signal.  The pulses are both in the second part of the cycle.  The relative position of the pulses is determined by the level of the signal.  WELL THAT'S PRETTY INTERESTING!  It's almost like a synth oscillator doing amplitude controlled PWM.  I tested it with a square wave input which helps show some of the time-delay pulse shaping behavior.

OK now I tested it with a sine wave and what it looks like it does more than anything else is to create a big pulse when the input signal does a negative going zero crossing.  But it's not doing this by overdriving a typical gain stage.

I'll grant you there are limitations to this simulation.  So I think I will build one and see what it's really doing.  Thanks for the idea.

This circuit is currently defying my ability to describe it as a collection of other well known building blocks.
Title: Re: Harmonic Percolator - make one!
Post by: garcho on July 31, 2013, 02:14:42 AM
Quote
This circuit is currently defying my ability to describe it as a collection of other well known building blocks.

I think that's partly why it's so popular here.

Take tca's advice and read that thread.
This is from veteran Gus. (http://www.diystompboxes.com/smfforum/index.php?topic=99785.msg876218#msg876218)
Title: Re: Harmonic Percolator - make one!
Post by: Digital Larry on July 31, 2013, 03:10:48 AM
Hmmm.... LOL.  Not trying to be a snob, and I don't have a better explanation myself, but none of the given explanations are really jingling my chain at this moment.

One thing I noticed in tca's simulations is that you can see the nulls in the spectrum corresponding to the duty cycle of the pulse.  For example, we all know a square wave (duty cycle = 50%) is missing all of the harmonics multiples of 2 (which is 1/50%).  Here it looks like the duty cycle is 1/6th and so the harmonics which are multiples of 6 are at a minimum.

I don't agree that making the negative pulse bigger adds more 2nd harmonic.  It just makes the whole waveform bigger.  And the little peaks on the top edges of the negative going pulses are higher harmonics than 2nd.  The effect of clipping diodes would be to smooth off any sharp peaks more than anything else.  So compared to clipping a sine wave, which adds harmonics, I'll be so bold as to claim that in this case, the clipping diodes create both level compression and a possible reduction of higher harmonics due to smoothing.
Title: Re: Harmonic Percolator - make one!
Post by: tca on July 31, 2013, 05:41:11 AM
I've been doing some LTSPICE simulations on it.
The problem with simulating this circuit is that what defines it does not show by simply putting a 1kHz sine wave as input. This only shows the clipping behavior. There is more to it. The "novel" thing about this little circuit is the intermodulation distortion.

One simple method that can work using an oscilloscope and sims software is La Bel's method. For more detail see: Chapter 14. FIDELITY AND DISTORTION pg. 614 (http://www.paleoelectronics.com/RDH4/CHAPTR14.PDF)

To see this in a quick way feed the circuit with two signals with frequencies f1 and f2 (f1<f2) sufficiently apart and with significant different amplitudes (4:1) and check the frequency response (amplitude spectrum). The output will have frequencies: f1+f2, f1-f2, and other linear combinations. That is why it is easy to get feedback with you guitar and so many "things" comes out of it (you don't need the output diodes for this).


I think Gus explanation is right and concise.

P.S. (edit)
Just added some refs and correct some statments.

Title: Re: Harmonic Percolator - make one!
Post by: Digital Larry on July 31, 2013, 09:32:53 AM
Oh god I am SO embarrassed.  I had a connection in the wrong place.  It's clearly an infrared remote control!   ;)

The assumption on which sine wave analysis is deemed "accurate for other signals that can be described as summations of exponentially decaying sinusoids" is that the circuit is linear (this one clearly isn't) and "lumped and constant" (but let's forget about those for now - though it's probably lumpy at least).  But I can't help myself, I just like to see what happens in the simplest case.

Now you and Gus may be entirely correct about the sonic result being due to intermodulation.  But that covers a lot of possibilities and still doesn't explain how the specific circuit works.  I was going back to "when the input signal goes up, then the current goes this way for awhile, until the voltage is sufficient for Q2 to start conducting again, and then the resulting voltage spike though the capacitor turns on Q1 until such time that blah blah blah blah".  That's just trying to understand what voltages and currents are doing in the system without trying to reduce it to a simpler problem.  And I think Steve Albini's description of how it works is (sorry) hogwash, so to have him dancing around in stilts while delivering this doesn't help.  Although I am suitably impressed by his other activities.

Still mystified and impressed.  Thinking about creating a "random circuit generator" software because I'm guessing that there's maybe just ONE, but a good one, made out of 2 or 3 transistors and a handful of R's and C's that will... you know... catapult me to stardom and... z...zzzzzz..zzz.z...  what?  I'm posting on diystompboxes forum????  Oh the shame!   ;D

P.S. muito obrigado para os links...
P.P.S. My "Radiotron Designer's Handbook" is a treasured heirloom given to me by my grandfather  :)
Title: Re: Harmonic Percolator - make one!
Post by: tca on July 31, 2013, 09:47:08 AM
Oh god I am SO embarrassed.  I had a connection in the wrong place.
That happens to all of us... that's part of the fun.

I've been playing with this La Bel's method and really works on a sim! (see link above) A thumbnail calculation gives an almost 100% percentage IM distortion for a full power chord. I don't have much time to put the results here but I encourage someone to try it out (it really deserves an entry on the sims board) and see it.

Cheers.
Title: Re: Harmonic Percolator - make one!
Post by: Digital Larry on July 31, 2013, 10:18:16 AM
If you know a lot about music theory (I don't) and you hear a cool piece of music that you like, some people might be tempted to deconstruct it in terms of harmony, arrangement, voice leading, rhythm, etc. so that if they wanted to reproduce some aspect of that specific effect, they'd be able to, knowing what went into the original.  Whether the composer of the original piece had those things in mind at the time cannot be assumed though.  For example, a lot of Todd Rundgren and Frank Zappa tunes have a certain harmonic "sound" that is partially the result of their typical chord voicings. 

So it is when I look at these circuits.  I have textbook and practical experience with designing electronic circuits.  When I see something like this I try to deconstruct it, partially to try to figure out what the designer had in mind when they developed the circuit.  And this circuit is so unique that I conclude "wow that guy was a genius" or "wow happy accident"!

I still think that the designer of the Tube Screamer was TRYING to make a diode clipper by putting back to back diodes in the feedback loop of an op amp circuit.  But because it was a non inverting topology, the diodes don't "clip" the signal.  Rather they create a piecewise linear amplifier where the gain goes from (really high) to one when the diode starts conducting.  Maybe it's a subtle difference sonically but electronically, it's a huge difference.  To me anyway!
Title: Re: Harmonic Percolator - make one!
Post by: Digital Larry on August 01, 2013, 10:13:14 AM
I've listened to a few of the demos and my first thought is that it sounds a lot like Neil Young "Rust Never Sleeps" or other Crazy Horse stuff where it sounds like his rig is constantly about to explode.  Anyone know if Neil uses one of these, or is his rig really about to explode?
Title: Re: Harmonic Percolator - make one!
Post by: pinkjimiphoton on August 01, 2013, 02:10:32 PM
i can't "SHOW" it yet,  but i can let ya hear the mod i mentioned earlier in the thread.

AND i took this thing out and rocked the bejesus out of it live last nite, and it stood up real well in the live situation, better than i expected and much better than the other percs i've used. i was surprised. sadly, the sh!tty video quality doesn't let you catch all the nuance you can hear live with the percolation/focus mod done, but i think enough will get thru to show the difference the modification makes. let me know what you guys think..

Title: Re: Harmonic Percolator - make one!
Post by: inductor on August 01, 2013, 04:14:19 PM
I've listened to a few of the demos and my first thought is that it sounds a lot like Neil Young "Rust Never Sleeps" or other Crazy Horse stuff where it sounds like his rig is constantly about to explode.  Anyone know if Neil uses one of these, or is his rig really about to explode?

Neil uses a a rinky dink tweed deluxe. So yeah his amp is about to explode.
Title: Re: Harmonic Percolator - make one!
Post by: garcho on September 24, 2013, 06:51:50 PM
trace PDF (http://www.aronnelson.com/gallery/main.php/v/diyuser/harmonic+percolator+trace.pdf.html)

(http://farm8.staticflickr.com/7351/9923697534_15955d9ca6.jpg)
Title: Re: Harmonic Percolator - make one!
Post by: vitopower1 on July 27, 2014, 10:25:05 PM
I've been really trying to get that sub octave, sounds like you got it with this? 

Do I understand correctly that you went 91k after the PNP collector to the volume knob 3, wiper to 47r then back to the junction before the 47uf tant?

really digging the sounds in the vids

i think it's soft clipping the signal with the transistors, and using some kinda SCARY PHASEING MAGIC i totally DON'T UNDERSTAND to make it do all this!

seriously, i think something about the circuit seems to  cancel dissonant harmonics.

i can get octaves out of it now...easily. up. down. both. it's insane.  no idea how/why it works. also discovered adding power supply filtering seems to affect it adversely!!

the latest is the best sounding one... if you make that 91k resistor a 47k from the collector of the pnp to the top lug of a 50k pot, and tie the wiper of that to a 47r resistor, you will get ALL the sh*t in albini's video. seriously.

it's bizzarre. you can make feedback come out in harmonic chords some times.

it's crazy man, like really crazy how ccrazy this crazy thing really is..

once my girl gets up, i will try and shoot some video. that 91k is the main key to percolation. the other is the 1m feedback resistor on the npn.
Title: Re: Harmonic Percolator - make one!
Post by: pinkjimiphoton on July 28, 2014, 12:16:08 AM
beats me, been a while since i did it, but yeah, there's  only the one 91k resistor. you need to make the pot "float" so you can get above or below the value.
the idea was to be able to adjust each transistor individually.

the two pots are MADDENING. they do completely different things depending on where and how the other knobs are set.

i don't have this anymore, it's been released into the wild, so whatever i did should be in this thread, but sorry, can't look at the original to see what i did.
Title: Re: Harmonic Percolator - make one!
Post by: Chaloney on July 28, 2014, 07:35:03 PM
Vitopower1 thanks for reviving this thread! Jimi, thanks for the demo videos. Now I gotta order some junk transistors!  Love the sound of this pedal. Anyone know if tayda has any transistors that will work?  I have an order waiting for the next discount code...
Title: Re: Harmonic Percolator - make one!
Post by: pinkjimiphoton on July 29, 2014, 03:45:10 AM
chaloney, check your pm's
Title: Re: Harmonic Percolator - make one!
Post by: kgstewar on February 04, 2015, 09:47:03 PM
Wasn't sure which Harmonic Percolator thread to post to but this seemed as good as any. First just wanted to say thanks for all the fantastic information on this thread. I decided to build a straight-up HP with no diode switch, and put together a little PCB that uses surface-mount resistors and ceramic caps (0.1uF). It's a tiny PCB that just hangs off the pots and fits vertically into a 1590B. Put it together, plugged it in and it sounds GREAT. I've included a couple of pics of the PCB with just the SMD parts mounted. From the silkscreen you can see where the through-hole parts go.

(http://i1342.photobucket.com/albums/o780/kgstewar/DSC_9124_zpsc0805cbd.jpg) (http://s1342.photobucket.com/user/kgstewar/media/DSC_9124_zpsc0805cbd.jpg.html)
(http://i1342.photobucket.com/albums/o780/kgstewar/DSC_9128_zpsf7008a1a.jpg) (http://s1342.photobucket.com/user/kgstewar/media/DSC_9128_zpsf7008a1a.jpg.html)

Title: Re: Harmonic Percolator - make one!
Post by: pinkjimiphoton on February 05, 2015, 12:17:50 AM
that is freakin' awesome!
Title: Re: Harmonic Percolator - make one!
Post by: kgstewar on February 05, 2015, 08:42:32 AM
Thanks Jimi, your great posts and videos were super helpful!
Title: Re: Harmonic Percolator - make one!
Post by: pinkjimiphoton on February 05, 2015, 02:31:57 PM
just standing on the shoulders of giants bro.

would love to hear some clips!! ;)
Title: Re: Harmonic Percolator - make one!
Post by: Addy Bart on May 19, 2017, 10:13:58 PM
Sorry for digging out an old thread but I just made one of these using the Albini values with transistors and diodes from Small Bear, and the results sound quite disappointing. It's more like a polite overdrive. I'm not getting much bloom or octave. Quite sure there's nothing wrong with the build.

I tested the 2n404 and the hfe was around 160. It's not very leaky though, and I'm wondering if that's where the magic lies. So if someone has a couple of leaky 2n404 they could post to me (I'm in Norway) that would be sweet. Will gladly PayPal for them plus postage.
Title: Re: Harmonic Percolator - make one!
Post by: pinkjimiphoton on May 19, 2017, 11:32:47 PM
hey bro,
did ya try turning the ge q 180 degrees?
sometimes with ge, you can reverse beta them from what ya expect, and they will work better.
i know this to be true with this circuit.
leaky ge q's may not be the answer.. they got tone, but the noise they produce can be astoundingly bad.
with a HP, if the transistor is backwards, yep, you'll get a mildish transistor overdrive instead of nasty obscene gobs of percolation ;)
if that don't work, we'll figure out the next move.
can ya post your voltages, please?
Title: Re: Harmonic Percolator - make one!
Post by: hellwood on May 19, 2017, 11:53:14 PM
This circuit tortured me for about a year. extremely low gain / high leakage for Q1 worked nice, but was a bit noisy. I settled for a healthy 60hfe 2n404. I have switches for Ge / Si diodes as well as a 5-way rotary switch that changes both input and output caps simultaneously. I also put Q2 on a switch for germanium or silicon, and to make things more complicated, I have a bias knob for Q1. The germanium Q2 was high gain and leaky, and has a really nice grinding sound with the bias knob maxed but no octave. the silicon Q2 combined with higher value input/output caps, in addition to the diode switch on Si, as well as having my Q1 bias knob almost off really help the octave weirdness happen.
Title: Re: Harmonic Percolator - make one!
Post by: Addy Bart on May 20, 2017, 11:20:52 AM
hey bro,
did ya try turning the ge q 180 degrees?
sometimes with ge, you can reverse beta them from what ya expect, and they will work better.
i know this to be true with this circuit.
leaky ge q's may not be the answer.. they got tone, but the noise they produce can be astoundingly bad.
with a HP, if the transistor is backwards, yep, you'll get a mildish transistor overdrive instead of nasty obscene gobs of percolation ;)
if that don't work, we'll figure out the next move.
can ya post your voltages, please?

Thanks Jimi. I flipped the germanium and it sounds more like a fuzz, which is pretty cool. I'm using a pcb from Stomptown which fits in a 1590a, so I'm not sure if the orientation is correct or not... It's good to know you can flip the transistor anyhow.

Here are my voltages:

Q1: 2n404a.
C: 3.38
B: 3.45
E: 3.46

Q1: flipped 180 degrees.
C: 4.10
B: 3.52
E: 3.27

Q2: 2n3565.
C: 5.02
B: 1.46
E: 3.61

Diodes are 1n695.

With Q1 flipped, it's shelving the attack with the harmonics knob dimed, but I've got some more 2n404 coming from Newark, so hopefully there'll be one with lower gain I can try. I had an extra pcb so I populated that with values for the stock HP. It'll be fun to see how they differ, although I wish I'd been more patient and maybe used some trimpots for the collector resistors. Oh well, guess I can always try it on vero again. Would be great to make one that sings!
Title: Re: Harmonic Percolator - make one!
Post by: Addy Bart on May 20, 2017, 11:26:29 AM
This circuit tortured me for about a year. extremely low gain / high leakage for Q1 worked nice, but was a bit noisy. I settled for a healthy 60hfe 2n404. I have switches for Ge / Si diodes as well as a 5-way rotary switch that changes both input and output caps simultaneously. I also put Q2 on a switch for germanium or silicon, and to make things more complicated, I have a bias knob for Q1. The germanium Q2 was high gain and leaky, and has a really nice grinding sound with the bias knob maxed but no octave. the silicon Q2 combined with higher value input/output caps, in addition to the diode switch on Si, as well as having my Q1 bias knob almost off really help the octave weirdness happen.
Sounds like the ultimate HP! If I can't get mine to sound any better, I'll follow the mods mentioned here.  8)
Title: Re: Harmonic Percolator - make one!
Post by: pinkjimiphoton on May 20, 2017, 11:33:37 AM
the 404 was definitely backwards i'd say.
its been a while, but the e's are tied together and should be reading the same, no?
i'd try a different silicon one.

to quote myriad guys way smarter than me,  don't worry about part values/names. try whatever works. a pnp is a pnp, an npn is an npn ultimately, and their gain ranges can be vastly different.

i would try a higher gain q2 first, and see if it comes to life. if higher doesn't work, go lower. eventually you will find the proper balance and it will come to life and sing.

ge transistors are a pain in the ass!! the gain never stays consistent... if you touch it, or even BREATHE on it FFS, it can completely change!!
that said, in some applications, they just plain sound better.

try a silicon in q1 too, unless you're 100% more concerned with "mojo"... escobedo's jerkulator sounds to my ears every bit as good as the hp does.

as for albini...
in them videos, he's using a significant amount of amp distortion (and i suspect a fuzz before the perc, too) so don't expect it to sound like his demo. the hp is a weird beast, and can be pretty unpredictable in some cases.

worst case, if ya get stuck, if you can pay the shipping i can send ya some really crummy low gain ge's to play with. may be cheaper to just buy them tho.

i'll send ya a linky via pm to some surplus ge's
Title: Re: Harmonic Percolator - make one!
Post by: Addy Bart on May 20, 2017, 01:12:13 PM
the 404 was definitely backwards i'd say.
its been a while, but the e's are tied together and should be reading the same, no?
i'd try a different silicon one.

to quote myriad guys way smarter than me,  don't worry about part values/names. try whatever works. a pnp is a pnp, an npn is an npn ultimately, and their gain ranges can be vastly different.

i would try a higher gain q2 first, and see if it comes to life. if higher doesn't work, go lower. eventually you will find the proper balance and it will come to life and sing.

ge transistors are a pain in the ass!! the gain never stays consistent... if you touch it, or even BREATHE on it FFS, it can completely change!!
that said, in some applications, they just plain sound better.

try a silicon in q1 too, unless you're 100% more concerned with "mojo"... escobedo's jerkulator sounds to my ears every bit as good as the hp does.

as for albini...
in them videos, he's using a significant amount of amp distortion (and i suspect a fuzz before the perc, too) so don't expect it to sound like his demo. the hp is a weird beast, and can be pretty unpredictable in some cases.

worst case, if ya get stuck, if you can pay the shipping i can send ya some really crummy low gain ge's to play with. may be cheaper to just buy them tho.

i'll send ya a linky via pm to some surplus ge's
Nice one Jimi. I tried a couple of silicon PNPs for Q1 (2n2907A and 2n3906) and they sounded even more shelved than the 2n404a (not a bad sound in my book either... Almost like a tremolo). But flipping the 2n404a has done wonders, so thanks for the advice. I'm sure you're right about it being the wrong way round on the board. It's way more textured now and less polite. Actually sounds really good on the gain channel on my little Kustom amp - with a louder amp it'll start to sing I'm sure.

I've ordered twenty 2n404As (they were just a couple of dollars each from Newark) so hopefully I'll find the perfect match. If not, I'll PM ya. Thanks man!
Title: Re: Harmonic Percolator - make one!
Post by: pinkjimiphoton on May 21, 2017, 08:44:42 PM
awesome, rock on bro!
Title: Re: Harmonic Percolator - make one!
Post by: digi2t on December 16, 2019, 10:11:44 AM
Quick question for all the HP noodlers here...

Has anyone tried an all germanium version? I've been snooping through the net on this, and I don't seem to see anything along those lines.

Why I ask is because Phil and I have been planning a board for the HP, but using lead spacing more suited to older NOS parts. In the meantime, I've gone back to noodling with this circuit on the breadboard. I know, I know.... after all the work I did on it a few years back, you'd think I would have built this damn thing already, right? Nope. It's been sitting on the back burner, just simmering away. Anyway, where was I... oh yeah...

All germanium HP. OK, here's a schematic I drew up way back. Based on the original mixed si and ge version, using what I found to work well at the time. It's got some minor mods to the original, just to keep things quiet;

(https://i.postimg.cc/LYx0rCpT/Harmonic-Percolator-SILICON.jpg) (https://postimg.cc/LYx0rCpT)

While I really liked the flat out roar of this circuit, there was always a hint of trailing fizz that.... I dunno... just bugged me. Didn't matter if Q2 was high gain, or low gain, it was always there. Perhaps that's what kept putting me off building this. Anyway, with nothing but time on my hands, and with a bunch of GT404's kicking about, I thought to myself, "What would it sound like with a germ in Q2?". I measured one up, and threw it in there. It seemed to be way less fizzy than the silicon Q2 circuit. I swapped out the 91K collector resistor for a 100K trimmer, and started messing with the bias. This is what I have on the board now;

(https://i.postimg.cc/94kj9Q4V/Harmonic-Percolator-GERMANIUM.jpg) (https://postimg.cc/94kj9Q4V)

I retweaked the Q1 and Q2 voltage to what's stated in the drawing, and wow... it sounds prrrreeeeeeettty darned good! Actually, much better than the mixed version. With the Harmonics pot dialed back to 50%, the roar is quite acceptable, but allows for very nice clean up when the guitar volume is rolled back. With Harmonics at 100%, well, the roar is moar, but guitar roll back gives a nice soft overdrive chunk. Really sweet!

I also found that C3 and C5 could be tweaked to suit single coil or humbucker equipped guitars quite nicely. 10n for really fat buckers, or up to 47n for thinner single coils. I find that 22n is a nice all rounder. YMMV

So, has anyone tried this angle before? If anyone has any PNP and NPN germs kicking around, can you try this, and give me your thoughts?
Title: Re: Harmonic Percolator - make one!
Post by: pinkjimiphoton on December 16, 2019, 11:38:09 AM
i did years ago, dino, a couple versions, including alll npn. they all sounded about the same to my ears, but i don't really remember what i did, its been at least 6 or 7 years since the last one.
when i get done with the latest order i'll see if i can mess with it on the breadboard some.
i found this circuit to be REALLY weird and almost ANYTHING will fuzz in it pretty nicely in almost any combination, ge, si,npn and pnp. they don't necessarily have to be npn/pnp with ge as i recall. a lot comes down to leakage and gain.

wish i was more help. making popcorn.

ps... merry christmas to you and deb bro! hope all is great!
Title: Re: Harmonic Percolator - make one!
Post by: digi2t on December 16, 2019, 08:10:54 PM
wish i was more help. making popcorn.

ps... merry christmas to you and deb bro! hope all is great!

No worries bro. It's just been a while since I futz'd with this circuit, so I was just looking for someone to validate what I'm hearing.

And a very merry Christmas to you and yours, and of course, happy holidays to all here as well. Quiet on all fronts here, just like we like it.  :icon_cool:
Title: Re: Harmonic Percolator - make one!
Post by: duck_arse on December 17, 2019, 08:34:06 AM
Dino - if you have a P416b lying about, plug that in for the pnp. when I built my coffee pot, I was trying to tune for "the sub octave", and the P146b didn't suit in that version - but it sounded ..... well, it grabbed me as the best of the russians I cycled thru the bb. couldn't hurt to listen, could it?

are you getting subs on yours now?
Title: Re: Harmonic Percolator - make one!
Post by: digi2t on December 17, 2019, 01:41:14 PM
Dino - if you have a P416b lying about, plug that in for the pnp. when I built my coffee pot, I was trying to tune for "the sub octave", and the P146b didn't suit in that version - but it sounded ..... well, it grabbed me as the best of the russians I cycled thru the bb. couldn't hurt to listen, could it?

are you getting subs on yours now?

I do believe that I do have 416's, from the Wow Signal build if I'm not mistaken. I'll check tonight and give it a whirl. No, no subs, but I'm not tuning for them either. Just wanting to kill the fizz on the decay, which I seem to have done with the germ NPN. It sounds quite woolly. I took the breadboard into the studio yesterday, and tried it at volume, and it was quite pleasing indeed. It made cycling the guitar volume very effective.

I'll check my stash and report back.
Title: Re: Harmonic Percolator - make one!
Post by: pinkjimiphoton on December 17, 2019, 03:05:42 PM
found this, can't seem to find all the graphics tho

https://www.diystompboxes.com/smfforum/index.php?topic=99596.msg887302;topicseen#msg887302


(https://i.postimg.cc/Mc56zRJV/germonic-jerkulator-1.gif) (https://postimg.cc/Mc56zRJV)
Title: Re: Harmonic Percolator - make one!
Post by: pinkjimiphoton on December 17, 2019, 03:14:38 PM


https://www.youtube.com/watch?v=NlUf9ZMt0h4

the germonic perc from days of yore

"harmonic percolator, but all germanium, no silicon.
2x 1n34a diodes, one 2n2273 ge hfe 87 one ac176 ge hfe 80"
Title: Re: Harmonic Percolator - make one!
Post by: digi2t on December 17, 2019, 07:54:20 PM
Yup, that's what I'm talking about. Much more organic, though I've stayed down in the gain range.

I've tried the following in Q1 tonight;
- MP42B - gain 78 - leak 0.0
- MP16B - gain 52 - leak 0.0
- P416A (sorry duck, no Bees) - gain 41 - leak 0.0
- 1T308B - gain 67 - leak 0.0

Q2 keeps the GT404B, with a gain of 62, leakage at 0.1mA.

My favorite combo to date is the 308/404. I also reduced the 220K feedback resistor on Q1 to 205K (strange value, I know, but I had I had some really cool glass resistors on hand, so I'm going for maximum Spaceman mojo here). This edged back the fuzz a tiny bit. Finally, I found that tweaking the collector resistors so I get 1v on Q1C (10.8K), and 2v on Q2C (74.7K) is really the sweet spot. By "sweet spot" I mean when you strike an open chord and let it ring, you get shimmering harmonic notes that cascade through the mix as the chord decays. Also, the clean up is beautiful. There's still so much gain on tap that you can easily just run the Harmonics pot at 50%. Plenty of bark just loafing. Crank the Harmonics pot and it just gets nasty quick, in a good way though. There's a crispiness to it, but not fizzy. It'll probably work really well on a darker amp, which I plan to test on tomorrow. Traynor YBA-3 Custom Special > 2 x 12" Texas Heats. I also have a Univox 1051 on standby as well. It'll be Doomsville around here tomorrow morning as soon as Deb steps out the door. :icon_cool:

The fact that the two transistors are close gain-wise might have an impact, though I'm really not sure. All I know is that using transistors in the Q1 spot that were higher/lower didn't tickle my ears like the 308 did.

That's it... calling it a night.
Title: Re: Harmonic Percolator - make one!
Post by: MaxPower on December 19, 2019, 12:10:24 PM
Finally tried this. The jerculator(sp?) version anyway. If anyone wants to make an audio oscillator just disconnect the 22uf cap. Frequency range is limited as is but can be adjusted by the input pot and/or your guitar volume/tone controls. The waveform sounds more sawtoothy than square to me, if anyone cares and can be bothered to check it with a scope. Similar to those relaxation oscillator circuits I guess.

And no, playing the guitar has no effect.
Title: Re: Harmonic Percolator - make one!
Post by: digi2t on December 19, 2019, 12:45:04 PM
Follow up on my previous report....

As is the norm, a 15w transistor practice amp, feeding a pair of Bose headphones might sound glorious, but real world conditions didn't bear quite the same results.

Not that I had to make wholesale changes mind you. Simply tweaking the emitter voltages on both transistors seemed to work fine. I ended up with about 1.8v on Q1, and 2.4v on Q2. I was still getting a tiny bit of fizz at 1v and 2v, but the tweak cleared it up. What that amounts to resistance-wise I can't say at the moment, the paper is at home. I'll add that in later today. Of course, there's also the "breadboard vs. boxed" factor. It might be just me, but I've had a few fuzz circuits on the breadboard that react one way, only to sound really different boarded and boxed. We'll see.

Overall, quite respectable. Like I said, lots of bark and bite at half throttle, with adequate flexibility via the guitar volume. The clean up wasn't what I was hearing through the 15 watter. In my best Hippynese - through the YBA, it gave a bit more grit to the stringiness when you rolled off the guitar volume, but cool nonetheless.

I guess I'm at the point where I'm willing to box this. Now... if only the boards would get here. :icon_rolleyes:

UPDATE:

Resistances for the Q1 and Q2 collectors are 16K and 98K respectively. That gives me 1.219v and 1.898v on the respective collectors. You can also push Q1 collector resistance alone up to 26K, which ups the voltages to 1.815v and 2.440v respectively. This pumps up the roar up a bit more, but the roll off is dirtier. It's a trade off. Still gives excellent performance though.
Title: Re: Harmonic Percolator - make one!
Post by: rankot on December 21, 2019, 09:43:47 AM
I'm having trouble with hfe measurement of my Ge trannies: if I measure with my DMM, they're from 80-120, if I measure with my GM328 component tester, they all appear with hfe=60-62. Whom to believe???
Title: Re: Harmonic Percolator - make one!
Post by: digi2t on December 21, 2019, 09:47:22 AM
I'm having trouble with hfe measurement of my Ge trannies: if I measure with my DMM, they're from 80-120, if I measure with my GM328 component tester, they all appear with hfe=60-62. Who to believe???

I should specify, I test all my transistors with a Peak Atlas DCA55. Other than that, I would use R.G. Keen's method of testing germanium devices.
Title: Re: Harmonic Percolator - make one!
Post by: digi2t on December 29, 2019, 05:36:23 PM
FINALLY! Committed to a board, and ready to box. Only took.... how many years?  :icon_lol:

(https://i.postimg.cc/62qzD61h/Build.jpg) (https://postimg.cc/62qzD61h)
Title: Re: Harmonic Percolator - make one!
Post by: amz-fx on December 29, 2019, 06:46:53 PM
I'm having trouble with hfe measurement of my Ge trannies: if I measure with my DMM, they're from 80-120, if I measure with my GM328 component tester, they all appear with hfe=60-62. Who to believe???

Transistors can yield different hfe values if tested at different currents. Higher current usually equates to higher gain measurements.

http://www.muzique.com/news/transistors-and-hfe/

regards, Jack
Title: Re: Harmonic Percolator - make one!
Post by: rankot on April 17, 2020, 02:00:50 PM
I've just finished one with the following values:
Q1 AC152, hfe=41, Vc=2.55V
Q2 2N2369, hfe=55, Vc=6.77V
B100k instead of A100k for Harmonics pot, gives more control, at least to my ears.
Diodes 1N34x2 + BAT46+1N4148 (switchable)
R1 220k
R2 20k
R3 750k
R4 18k
R5 4k7

Sound is interesting, not sure if it is 100% original HP since I tested it on bass amp, but sounds quite good to me. I tried with trim pot in place of R4 and finally settled with this really low value, but it gives me the most volume. I don't know, maybe that's wrong, but sounds good to me. Maybe I could first set Q1 Vc, but I soldered R2 first and, since it is squeezed between other parts, it was very complicated to remove it and put a trim pot instead, so I settled with Q1 Vc at 2.55V.
Title: Re: Harmonic Percolator - make one!
Post by: rankot on February 04, 2021, 05:20:56 PM
Just finished another one for my late friend's little son - those are the values. It seems to be singing even nicer than the first one, which was closer to Albini specs. This one is almost classic HP. I used two pots to find sweet spots for collector resistors:
Q1 MP20, hfe 52, Vc=4.67V, Vce=0.22V
Q2 2N6517, hfe 140, Vc=5.84V, Vce=1.07V
(https://i.postimg.cc/LYx0rCpT/Harmonic-Percolator-SILICON.jpg) (https://postimg.cc/LYx0rCpT)
Resistor values, following schematic above:
R1 750k
R2 220k
R3 39k
R4 56k
R5 2k2
D1, C5 and C7 not installed, C3 is 1u.
Title: Re: Harmonic Percolator - make one!
Post by: Rob Strand on February 04, 2021, 05:39:05 PM
Quote
Q1 MP20, hfe 52, Vc=4.67V
Q2 2N6517, hfe 140, Vc=5.84V
Given the emitter voltage must somewhere in between those collector voltages  (not necessarily midway) ,
the collector emitter voltages are quite low, close to 0.6V.


EDIT:
After looking at digits's schematic, I remembered when he did that work he come-up with different voltages.  In particular the voltage at the collector of Q1 had a higher Vce that I'd seen in the past.   (On the schem he's quoting Vc which is measured to ground not Vce measured between c and e.)
Title: Re: Harmonic Percolator - make one!
Post by: rankot on February 04, 2021, 06:08:53 PM
I have also measured to ground - so those are Vc,gnd voltages, not Vce. I used pots for this and set them where I liked sound the most and I suggest that everyone do it that way, so no need to chase a voltage at all - chase the sound.
Title: Re: Harmonic Percolator - make one!
Post by: Rob Strand on February 04, 2021, 06:36:54 PM
Quote
I have also measured to ground - so those are Vc,gnd voltages, not Vce. I used pots for this and set them where I liked sound the most and I suggest that everyone do it that way, so no need to chase a voltage at all - chase the sound.
Yep, I realized that.   Since from you two Vc measurement we can guess the Ve is in between the two Vc say around 5.3V.   Since your Vc1 4.67V we can guess your Vce1 = 5.3V - 4.67V = 0.63V.    Digit's Vc1 on the other hand is about 1V much lower than your Vc1 of 4.67V, so that makes me think his Vce1 is somewhat larger than your 0.63V.

[Trying a bit harder with the numbers I got Ve = 4.89V, Vce1 = 0.22V and Vce2 = 0.95V, as expected both quite low.]




Late EDIT:

It's still possible for digit's circuit to get a low VCE across Q1.  What happens is the voltage between the emitters can drop down toward the voltage set on Q1's collector.
Title: Re: Harmonic Percolator - make one!
Post by: iainpunk on February 04, 2021, 09:14:33 PM
some ou you might already have read my recent posts and schematics, but i havent seen this thread before, and it seems a good place to post the schematic and name explain:

(https://i.postimg.cc/K494xXV5/harmonic-instant-coffee.png) (https://postimg.cc/K494xXV5)
the 39k resistors are just place holders, if you decide on building it, i recommend experimenting on breadboard beforehand to find the resistors that match your transistors and diodes best.
the 4n7 was initially selected becaus its the value i have most of, about 60% of all my caps are 4n7, but in lots of diffetent materials and packages, i tried smaller and larger caps, but i keep coming back to the 4n7, it just sounds the best to my ears.
i have also put my NPN transistor in reverse Beta, that gives a really nasty, nasal, noisy tone

i called it the Harmonic Instant Coffee
Code: [Select]
percolator coffee is nice, high quality, fine tuned by the masters of coffee making and soft in aroma's.
instant coffee is mediocre at best, poor quality, the cheapest beans are used and can be really harsh tasting.
Harmonic Percolator is nice, high quality, fine tuned by the masters of pedal building and is soft in tone.
Harmonic Instant coffee is NOT NICE, simplistic, cheapest parts are great for it, and can be really harsh sounding.

cheers, Iain

cheers, Iain
Title: Re: Harmonic Percolator - make one!
Post by: Rob Strand on February 04, 2021, 11:51:34 PM
Quote
the 39k resistors are just place holders, if you decide on building it, i recommend experimenting on breadboard beforehand to find the resistors that match your transistors and diodes best.
It's an interesting idea since it forces the collector-emitters voltages  to be low.  Probably sounds a little different to no diodes and stuffing around trying to get the bias right.    Maybe a comprimise is to only use one of the diodes then adjust the collector resistor of the transistor without the diode.

If we unravel the series connection of the Percolator it becomes something like Howies Metal Simplex.  Funny thing is the Metal Simplex sounds like a fairly low gain pedal.  Maybe the size of the CB resistors does that.

https://www.hgamps.com/2n3904-metal-simplex-fuzz/
Title: Re: Harmonic Percolator - make one!
Post by: iainpunk on February 05, 2021, 12:39:22 PM
i build a metal Simplex once, its a nice little fuzz/distortion with heaps of gain, but i put in 47k resistors for R2 and R4.
its indeed quite similar to the HP in topology, but can be made to sound really different.

funny how that website describes the schematic as ''although similar topology as old Fuzz Face.'' which made me chuckle a bit.
they have very little in common, only the fact that its 2 transistors cascaded...

that's also not how my metal simplex sounds, i guess we can hear the electric guitar being acoustic about as loud as the amplifier is in his clip.

on another note, the HP/HIC i have on my breadboard now is really harsh and gated, how do i lower the gating effect without lowering the harshness? the first stage is not gated, and the 2nd stage is quite gated, and there is a small cap in between them to make it harsher and more nasal, if i increase the gain of the first stage, i lose the harsh nasal vibes, how do i get more sustain, without losing the harshness?

cheers, Iain
Title: Re: Harmonic Percolator - make one!
Post by: Rob Strand on February 05, 2021, 08:32:41 PM
Quote
funny how that website describes the schematic as ''although similar topology as old Fuzz Face.'' which made me chuckle a bit.
they have very little in common, only the fact that its 2 transistors cascaded...
Yeah, you see that a lot.

It's a while since I've played around with the HP.   Using the designators on this schematic,
(https://www.fredric.co.uk/misc/HarmonicPercolator.sch.png)

I don't have a perfect way to tune it but I think the key is the VCE  (voltage between C and E) of each transistor.
For Q1:  want VCE1 0.2 to 0.4V ; higher values of 0.6 to 1V are workable but I think the low range is what people want.
For Q2:  want VCE2 0.9 to 1.5V ; wider range 0.6 to 2.0V is workable

The steps to set-up the circuit:
- Choose part values for R3, R4 either like in the George Giblet circuit or other. 
- wire-up the George Giblet circuit.
- Adjust R2 to set the VCE1 voltage
- Adjust R1 to set the VCE2 voltage
- repeat the last two steps one or two times if the required R1 and R2 values change a lot from the initial values.

The problem with adjusting R3, R4 is you have to make large adjustments to affect VCE1 and VCE2 and even then you need to have R1 and R2 reasonably close to start with.

So one tweak which I haven't played with is adjusting R3 and R4 *together*.   If you keep the sum of R3 and R4 constant you can trade the gains of the Q1 stage and Q2 stages.  For example if we start with R3 = 91k and R4=20k the sum is R3+R4 = 111k.  We can decrease the gain of Q1 by changing R4 to 10k.  In order to keep R3+R4 constant R4 needs to be 111k - 10k = 101k.   The reason for keeping R3+R4 constant is it doesn't affect the VCE1 and VCE2 that have be selected.

In order to set the VCE voltages we might end-up with R1 and R2 values which are much different than the original values.  A low value will decrease the gain of the stage.  A high value will increase the gain of the stage.    Way off values might mean the transistor isn't suitable.   Adjusting R3 and R4 together is a way we can fix the gain to some degree to compensate for way off R1 and R2.
Title: Re: Harmonic Percolator - make one!
Post by: rankot on February 06, 2021, 07:19:33 AM
So one tweak which I haven't played with is adjusting R3 and R4 *together*.   If you keep the sum of R3 and R4 constant you can trade the gains of the Q1 stage and Q2 stages.  For example if we start with R3 = 91k and R4=20k the sum is R3+R4 = 111k.  We can decrease the gain of Q1 by changing R4 to 10k.  In order to keep R3+R4 constant R4 needs to be 111k - 10k = 101k.   The reason for keeping R3+R4 constant is it doesn't affect the VCE1 and VCE2 that have be selected.

In order to set the VCE voltages we might end-up with R1 and R2 values which are much different than the original values.  A low value will decrease the gain of the stage.  A high value will increase the gain of the stage.    Way off values might mean the transistor isn't suitable.   Adjusting R3 and R4 together is a way we can fix the gain to some degree to compensate for way off R1 and R2.

In my last build, I did exactly that - mounted 91k collector resistors and 500k pots in parallel with them, then adjusted pots by ear - and to me the best position was close to the cutoff for both transistors, just tweaked a little to avoid some nasty decay oscillations on low notes. Then desolderet pots, measured their resistance, calculated parallel resistance of that with 91k and that was it.
Title: Re: Harmonic Percolator - make one!
Post by: Rob Strand on February 06, 2021, 04:40:14 PM
Quote
In my last build, I did exactly that - mounted 91k collector resistors and 500k pots in parallel with them, then adjusted pots by ear - and to me the best position was close to the cutoff for both transistors, just tweaked a little to avoid some nasty decay oscillations on low notes. Then desolderet pots, measured their resistance, calculated parallel resistance of that with 91k and that was it.
That's method is fine too.  Decreasing the collector resistors (R3, R4) makes the VCEs go up.   If you VCEs are too high you need to decrease R1 and/or R2.

Digit only adjusted R4 which is also fine but you can end-up with R4 being too low.   I think Digits has R4 around 12k, which is in he ball park of 20k.    However it's possible to have many set-ups which give the same VCE provided the sum R3 + R4 is constant.  For Digits's case R3 + R4 = 12k + 91k    = 103k.   So if we kept R4 at the standard 20k would could set R3 = 103k - 20k = 83k and it would produce the same VCE bias points for Q1 and Q2.    I haven't done the experiment to see how the sound changes when you  keep R3+R4 constant but allow the R3, R4 values to change.
Title: Re: Harmonic Percolator - make one!
Post by: rankot on February 07, 2021, 05:22:23 AM
I believe that hfe also has impact on this, and those are the final resistor values for my two build, with different transistors:

Q1 MP20, hfe 52, Vc=4.67V, R4=56k
Q2 2N6517, hfe 140, Vc=5.84V, R3=39k

Q1 AC152, hfe=41, Vc=0.66V, R4=5k1
Q2 2N2369, hfe=55, Vc=5.27V, R3=30k

Both found using "pots and ear" approach.
Title: Re: Harmonic Percolator - make one!
Post by: Rob Strand on February 07, 2021, 03:25:00 PM
Quote
Q1 AC152, hfe=41, Vc=0.66V, R4=5k1
Q2 2N2369, hfe=55, Vc=5.27V, R3=30k
That one is quite interesting.   It would be good if you had the emitter voltage so I could check the VCE voltages of Q1 and Q2.

If magic sound comes from a low VCE on Q1, then in this case Q1 would be expected to be quite leaky and the low R3+R4 sum value is a way of counteracting that.     If the VCE of Q1 is say 0.3V, then the emitters will be at VE = 0.66 + 0.3 = 0.96V.    So for Q2 the VCE would be 5.27 - 0.96 = 4.31V, which is much higher than normal.   If we assume VCE of Q1 is 1V, higher than normal, that puts VE=1.66V but VCE2 is still quite high at 3.61V.    Whatever way we look at it VCE2 is quite high so maybe it's not that important.   
Title: Re: Harmonic Percolator - make one!
Post by: rankot on February 07, 2021, 04:30:06 PM
Unfortunately, I didn't record the leakage and now I'm too lazy to desolder trannies and measure again. However, emitter voltage sits at 0.94V on this one with AC152 and 2N2369 (I can't measure another unit, since I gifted it yesterday to my late friend's son).

Probably hfe has some role in this, because 2N2369 has hfe of only 55, while gifted unit use 2N6517 with hfe of 140.
Title: Re: Harmonic Percolator - make one!
Post by: Rob Strand on February 07, 2021, 05:47:01 PM
Quote
Unfortunately, I didn't record the leakage and now I'm too lazy to desolder trannies and measure again. However, emitter voltage sits at 0.94V on this one with AC152 and 2N2369 (I can't measure another unit, since I gifted it yesterday to my late friend's son).

Probably hfe has some role in this, because 2N2369 has hfe of only 55, while gifted unit use 2N6517 with hfe of 140.

Thanks.  We can see VCE for Q1 is 0.94V-0.66V = 0.28V which fits the theory of that VCE1 needs to be quite low.  VCE2 on the other hand is 5.27- 0.94 = 4.3V,  way over the normal.   So maybe VCE2 is of secondary importance.

The hfe definitely comes into it.  Higher gain transistors will give lower VCE voltages.    Which is clearly seen on your two NPN transistors.   The pnp is tricky because high leakage will cause VCE to drop and so you might not see VCE matching up with the hFE.

Title: Re: Harmonic Percolator - make one!
Post by: rankot on February 08, 2021, 05:37:19 PM
And I think bigger hfe is better for Q2, because this one I have with lower hfe still has some low frequency oscillations (reduced when I put 2u2 capacitor instead of 100n at C3), while the one I gifted has none. Maybe I should try different transistors on my unit.
Title: Re: Harmonic Percolator - make one!
Post by: Rob Strand on February 08, 2021, 05:48:25 PM
Quote
And I think bigger hfe is better for Q2, because this one I have with lower hfe still has some low frequency oscillations (reduced when I put 2u2 capacitor instead of 100n at C3), while the one I gifted has none. Maybe I should try different transistors on my unit.
I don't have any good answers for the DC problems.   Some other pedals put resistors between the output of one stage and the input of the next and others use small emitter resistors.   The other way is playing with the cap values like you did.  Hard to know in advance if they change the sound for better or worse.
Title: Re: Harmonic Percolator - make one!
Post by: iainpunk on February 09, 2021, 03:19:01 PM
a simple 330 ohm to 1k emitter resistor on the Q2 side made all my oscillations disappear, under the 330 oh, they were still there and above 1k the amount of gain started dropping off to much, but mine isn't a ''true'' harmonic percolator, but my Instant Coffee version, i posted earlier.

i came across some issues with gating, i have Q2 in reverse Beta, with the right diodes*, this gives a beautifully broken tone, but it gates out the circuit, and if there is no current through Q2, the current through Q1 starts to sag until the middle cap is empty, which in turn made the gating worse.
my solution is a 10k from 9v to the middle cap to keep current through Q1 going, this made it way less gated, and retained the beautifully broken sounds. the cap voltage is 7,62v.

TLDR: if you have problems with gating, a resistor parallel to one of the stages might relieve the gated-ness

cheers, Iain

*i find that diodes have way more impact in the instant coffee than they have on the Bazz Fuss. i have a BYX10 on Q1 and an amber LED on Q2.
Title: Re: Harmonic Percolator - make one!
Post by: iainpunk on February 10, 2021, 03:20:20 PM
Instant Coffee Update:

there are 3 things i considder virtues of a fuzz, and i want them all, which is harder than you'd think, most of the time its a choose 2 situation:
- low end
- sustain
- raspyness

after a day of experimenting, i have come to a conclusion; having Q1 as high a gain as possible is better for everything, both bass, sustain and raspyness, the gain of Q2 determines its place on a kind of spectrum, from thicc and bass heavy to raspy with less bass, there is no magic combo with much bass and raspy harmonics. leakage is a bad thing here, it loses bass and gets less raspy, it gets just thin and soft.
after an hour or two, i selected a ASY29 as Q2, in reverse Beta of course, it gave me the best balance.
here is the new full schematic:
(https://i.postimg.cc/R6hrCZnK/HIC-ASY29-BC519.png) (https://postimg.cc/R6hrCZnK)
Q1 : BC519
Q2 : ASY29
D1 : BYX10
D2 : Amber LED

cheers, Iain