nothing crazy special, but nice sounding fuzz/octave up
based on the ETI "Struzz"
somewhat tweaked in, and set up to run on a SINGLE 9volt source instead of having to mess with charge pumps or multiple batteries etc.
major changes are tweakability to q1, adding an output cap and master volume, redistributing some of the gain a little bit for better fuzztone, "focusing" the octave with a cap in octave mode, making it less noisy than the original 741 based circuit... blah blah blah... will probably get some video going one of these days.
this and the original circuit sound nite and day different.
a big part of it comes down to the opamps... the ca3140/lm301 combo is hard to beat out of all the others i tried... that 3140 has some real magic to it.
https://www.renesas.com/us/en/www/doc/datasheet/ca3140-a.pdf
anyways, here's a schematic if anybody wants to give it a try. no layout for it yet, i just modded up an old "graymark" kit board, but the schematic is verified and works great.
(https://i.postimg.cc/t7VSwsPv/double-hit-deux.png) (https://postimg.cc/t7VSwsPv)
i mean, whats not to love? easy circuit, cleans up like a fuzzface, gotta decent octave built in... helllll yeah!
Nice project Jimi.
You should be able to replace the Q1 circuit with the input transistor stage of the Big Muff so as to eliminate the need for trimpots.
Best regards, Jack
hey jack,
thanks! and happy new year!
thats actually a great idea.... i will have to try it maybe next time i build one on vero.
this one was one of those "lets see how far we can take this crappy surplus fuzz kit" deals.
graymark international, or something like that. double sound fuzz. they sell the kits CHEAP! but they literally hogtie and sell ya into indentured servitude on the shipping if i recall. crazy.
juuuuuuust will fit in a 1590g i think it is. kind of a tall 1590 b.
tonite i looked at it funny for a while trying to figure out how best to do this. i think i can get the whole thing to fit in a too-small box with two footswitches and leds and 4 pots up top.
look forward to boxing it up. completely different animal.
i THINK the trimmers on q1 have quite an effect on the octave and how much noise artifacts get thru. i found when trying different combos of opamps... 741 5534. tl061 and lm301s all sounded very different, and had different characteristics with "spittyness" and noise. the 3140 was just a hmmmm.... single opamp, lets see kinda thing, but MAN! low noise, very clean octave, decent headroom and an actually useable fuzztone.. i'm diggin it.
well...
so far.....
you know how the fuzz addiction goes. tomorrow's fuzz is just 23 hours away....
;)
peace, my friend
Quote from: pinkjimiphoton on January 13, 2019, 09:54:59 PM
a big part of it comes down to the opamps... the ca3140/lm301 combo is hard to beat out of all the others i tried... that 3140 has some real magic to it.
https://www.renesas.com/us/en/www/doc/datasheet/ca3140-a.pdf
anyways, here's a schematic if anybody wants to give it a try. no layout for it yet, i just modded up an old "graymark" kit board, but the schematic is verified and works great.
(https://i.postimg.cc/t7VSwsPv/double-hit-deux.png) (https://postimg.cc/t7VSwsPv)
i mean, whats not to love? easy circuit, cleans up like a fuzzface, gotta decent octave built in... helllll yeah!
Thanks for mentioning CA3140, never heard of it before. Local supplier stocks it, I might try it somewhere, sometime. ;D
On the schematic, op-amp negative rail pins (#4) are connected to the 4.5V. Is that a feature? ???
i dunno about "feature" but it appears to be working. ;)
originally they were grounded, as in ground being the midpoint between + and - 9 volts (+9/-9).
shoot, now i gotta look at this thing lol
just checked, and yes, 4.5v. i'll try and take some pics of the original project book and pics of the actual pcb.
pin 4 of both oa's connect to the half supply voltage at the junction of the two 10k resistors in the power supply.
on the original project, they'd be connected to ground between the +/- 9 volt rails. connecting them like this i'd never done before, but it sure seems to work well.
originally, i thought it would be more complex than it was. pin 4 on both would have been connected to the negative terminal of the lower battery. that makes no sense of course so i gotta scan this thing. ;)
but yeah, from what i gather, the half voltage or ground can be used pretty much interchangeably in a case like this.
or its a real happy accident? lol
beats me
all i know is it works and sounds really good compared to the original project!
the ca1340 is a really cool chip, i had no clue to how cool til i plugged one in. ;)
be back soon with scans n stuff
ok, here ya go, the original stuff. if ya compare it to the schem posted above ya can see the changes and differences ;)
all my value changes etc are scribbled on this
(https://i.postimg.cc/kVGJFWH5/double-hit-deux-orig-schem.png) (https://postimg.cc/kVGJFWH5)
this is from the bottom of the board, and the power supply as i set it up sits to the left
(https://i.postimg.cc/dkGz81J1/double-hit-deux-orig-pcb.png) (https://postimg.cc/dkGz81J1)
how it all lays out originally, before i modded it...
(https://i.postimg.cc/z3XsLq9J/double-hit-deux-orig-layout.png) (https://postimg.cc/z3XsLq9J)
(https://i.postimg.cc/9RNJwH7M/double-hit-deux-orig-layout-inst.png) (https://postimg.cc/9RNJwH7M)
and mine, again.
with all the weird shit on it. ;)
(https://i.postimg.cc/t7VSwsPv/double-hit-deux.png) (https://postimg.cc/t7VSwsPv)
how it all lays out on the graymark board. yep, battery + goes to the upper right, battery - goes to lower right.
(https://i.postimg.cc/vcYg42yR/double-hit-deux-board-layout.png) (https://postimg.cc/vcYg42yR)
so yeah, i put pin 4's to the middle of the power supply instead of ground. this way, one battery, done deal. i dunno if its RIGHT, but it sure sounds good! ;)
this is what i did for a power supply. the 4.5v goes to pin 4 on both chips
(https://i.postimg.cc/y3ZDH24t/double-hit-deux-power-supply.png) (https://postimg.cc/y3ZDH24t)
(https://i.postimg.cc/9RNJwH7M/double-hit-deux-orig-layout-inst.png) (https://postimg.cc/9RNJwH7M)
so, i boxed this thing tonite. ended up ditching the e resistor on q1, and went with a mpsa13 for a transistor after sampling a bunch of npn ge and si's. that gave the best fuzz on its own, almost overdrivey more than fuzz, and helped even out the volume with the octave side.
basically, the fuzz volume about half way up = the octave volume pegged.
its not super loud, but it cleans up really well with guitar knob twiddling, even on the octave side.
the octave side is weird. but cool. can still kinda hear the fundamental in there with the octave, like on "the sky is burning" by bad company.
enough output now to be over the unity gain it was, just slightly.. hard to tell cuz its late and i already got the warning text from the woman lol...
this thing is @#$%ing HIP with a ge fuzzface in front of it, pegged. unreal weird stuff,.... like playing an electric saxolin or something... it spits and swells into notes, and if ya play legatto its like it charges up and goes into hyperdrive. weird weird weird!!!!
but i like it.
video tomorrow....
errrr.. today
but here's the thing... how the hell can this thing possibly even work? the ground is, i think, just to the chassis for the pots n jacks like a normal box...
but the 9v power hooks up so the + goes to the top of the 10k x 2 voltage divider,
the - of the battery/ground goes to the middle of the voltage divider, and the bottom of it goes to ground.
something seems very wrong here to me. i would expect the - of the battery to go to ground, not the center point, right?
i suspect the chip has a lot to do with it... cuz it can run on pretty low voltage
but i guess what i'm not getting is i thought the mid point of the voltage divider would be ground in between two 4.5v sources for all intents, as all i'm giving it is a 9v battery...
maybe its just cuz its real late and i'm tired, but there's something mighty weird going on here that i don't think i've ever encountered before with the way i hooked up the juice to it.
i would be jazzed and grateful if some kind soul could enlighten my darkness, cuz man, i can't even find a speck of light as to how this could work.
how the hell does ground get made without returning to the circuit somehow?
is it happening thru the pots?
duh. i just looked. ground gets made thru the bottom resistor. but i still don't get
why the bottom of the battery/ ground of the power supply only works hooked up to the center point of the voltage divider.
i'm confusing myself more i think lol
:o
i really don't get it :icon_eek: :icon_rolleyes:
Yes, that power arrangement is totally whacked. The chip pin4's should go to battery negative and the ground symbols and chassis to the 4.5v mid point. So with dmm neg on the chassis, pin4's will read -4.5v and the +9v connections would read +4.5v.
If you had it as it should be with the mid point grounded, it would have to run on its own power supply and not in a common daisy chain power with other pedals.
Of course, the modern way of doing it is to replace the -9v battery with a 7660 or whatever converter chip so it runs as originally designed but from a single +9v power.
Why would it work wired as shown? Yes, CMOS can run low voltage, but I think more important is they can work even if the inputs swing negative of the pin4 voltage, so it can get away with pin4 voltage being higher than ground.
weird weird weird, jim!!
i DID try hooking it up the other way, not a sound from it.
i think i drew it wrong on the hand drawn schematic the way i drew the power supply, on the layout of the pcb i drew the parts on is actually right.
i will take some voltage readings of it when i go back to my dungeon, i tried it up here with the volume cranked <little woman is out> and i got an oscillation problem i gotta suss out.
the 2.2n cap from pin2 to ground of u1 is gonna get ditched i think, it does make the octave sound better but it detracts a lot from the fuzz.
live n learn.
i will try hooking up the power the other way and see if i can get it to fire.
thanks for the help bro!
in the mean time
DON'T TRY THIS YET other than on a breadboard!
ok, so i found some problems, fixed some others and re-drew the whole thing as it sits now.
i still don't really get how the power supply thing works. i had drawn it WRONG, of course. for the life of me, i don't understand why this thing just wouldn't run off a plain old 9volt battery. is the voltage divider thing really necessary? doesn't seem to do anything or be hooked up to anything.
that said, without it? circuit won't fire. ;)
and apparently this has a ground AND a - 9v connection, even tho the -9v of the battery and ground connection are to the same place on the power supply jack.
standard tip/ring/sleeve on/off input jack.
but dig this.... if ya connect the - side of the 9v supply DIRECTLY to ground, it will NOT fire. even tho its connected at the ring of the input jack!!!
weird weird weird.
but it sounds pretty good. i will try n get more video tomorrow, my family is probably ready to kill me.
still can't get the octave part as loud as the fuzz. may add a simple boost stage hacked in there somehow.
changed the diodes in the rectifier. one side is pink led, the other 1n34 and pink led in series. if ya want it to swell, use two 1n34's in series on both sides, and run a fuzz face into this thing. holy cow.
if ya want this to clean up with volume pot on guitar, ge is the way to go. i opted for the ge/led combo in search of more balls on the fuzz, which stock is fairly anemic. two leds makes the octave two spitty, and no possibility of turning your guitar down.
changed the 10k bias trimmer on q1 to 50k. it makes a huge diff on the volume of the octave. i was reading 23k with one side disconnected, so 22k should be ideal.
i ditched the cap bypassing pin 2 to ground on u1. it sounded cool, but not worth keeping in the end. it really made the octave pop out more... but... the big problem with this and switching from fuzz 1 to fuzz 2 is that each wants opposite settings on the gain pot.
the fuzz wants the gain/sustain pegged. when ya go to the octave, it wants it off. what to do?
well, i used the same footswitch connections i had used for the cap, and simply ran wires to the pot.. the wiper, and the unused side, so when the footswitch is in octave mode, it automatically shorts the pot off. huge improvement. trying to find a happy medium meant a splatty jawari-esque octave and a gated buzzy fuzz. now ya can just crank the thing up full and get a decent sound out of each. some folks may like the gain down a bit for more velcro-y sounds.
as it turned out, i totally dropped the ball on the power supply, and i apologize for that. i'm still confused on it.
i checked today, i had thought the - of the battery/power supply was jumpered to the junction of the two 10k resistors and the 33u cap, but that node is connected to nothing. the cathode of the cap is to ground along with the low side of the voltage divider. the 33u cap comes off the junction of the two resistors, but it doesn't seem to be connected to anything else. without it? won't run right, tho it makes some really amusing envelopey sweepy weird noises, particularly with the tone knob on the guitar down.
weird weird weird.
ok, that it for changes. for sure, for real, THIS is what i got running. all hacked onto that cheezy graymark kit board
(https://i.postimg.cc/ns32PRh9/double-hit-deux-rev-2.png) (https://postimg.cc/ns32PRh9)
so the billion dollar question.... why the hell is -9v different from ground on this? or is ground floating somewhere between ?
like... i am confused more by the minute. or is it really somehow
its running at +/- 4.5volts with ground in the middle somehow?
i don't get it at all.
this thing sounds great with a fuzzface driving it, too. holy crap. it compresses like crazy, then releases when ya play legato and automatically swells in. its sick! ;)
OR i messed something else up. :o :icon_rolleyes: :icon_eek: ::)
grafted in a big muff input stage to replace what was there. still not digging it.
messed with it some more tonite... trying to get a useable volume for the octave part is problematic in that if ya do get a good octave sound, the fuzz sound suffers. oy. if ya get a good fuzz that doesn't gate too much... i hate crackly fade outs... then the octave is weak and sucky.
gotta play with it more tomorrow.
determined to make this sucker run on 9 volts and sound good somehow. ;)
stay tuned ;)
The -9V is used only for the op amps. For more headroom, I guess? I'd try the following mod, simply biasing the non-inverting pin of the first op amp and connecting both -V's to GND:
(https://i.postimg.cc/FdswBFvb/dhd-mod.png) (https://postimg.cc/FdswBFvb)
I'm too dumb to figure out the second stage input biasing with all those diodes in place :icon_lol:, they seem to be connected... so it may work. :D
If the ground was floating instead of halfway, and if it has connections to the + & - around the circuit - real via resistors/pots or thru leaky caps, then it might well "float" to somewhere in between the supply voltage.
I see in your readings U1 pin 3 as 2.23v. That voltage will be coming in via the 10k resistor, not from the amp pin - so a voltage reading at the ground end of that resistor might prove if it really does have that ground connected to supply -9v.
I got a warning - the fact that the CMOS amp may have an input "misbiased" could be an important part of the effect you hear. There a well known single amp full wave rectifier in the RCA CA4140 datasheet figure34 that has both pin 4 and pin3 to ground and deliberately referenced to 0v instead of 1/2V. The way that rectifier works absolutely relies on the 0v bias and the CMOS chips ability to handle an input that's more negative than the negative supply pin.
hahah...
well, connecting them to ground doesn't work. tried it. connecting them to the half voltage doesn't work. tried it.
i had my rhythm guitar guy here yesterday, full on EE. he couldn't figure out how or why the thing worked.
his suggestion? run it on TWO 9 volts and see what happens lol
Quote from: diffeq on January 16, 2019, 04:36:46 AM
The -9V is used only for the op amps. For more headroom, I guess? I'd try the following mod, simply biasing the non-inverting pin of the first op amp and connecting both -V's to GND:
(https://i.postimg.cc/FdswBFvb/dhd-mod.png) (https://postimg.cc/FdswBFvb)
I'm too dumb to figure out the second stage input biasing with all those diodes in place :icon_lol:, they seem to be connected... so it may work. :D
Quote from: anotherjim on January 16, 2019, 04:54:12 AM
If the ground was floating instead of halfway, and if it has connections to the + & - around the circuit - real via resistors/pots or thru leaky caps, then it might well "float" to somewhere in between the supply voltage.
here's the thing. if i connect the -9v (the neg on the battery or power supply) directly anywhere but the star ground on the input jack, it just won't fire!! if ya hit it super hard, ya may get a cracke or phart.
the way its wired is weird. from the power in jack, +9v goes to the board and then the voltage divider for the two led's. normal, right? the - from the power in jack goes to the input jack sleeve. also normal. but if ya hook the negative up to ground, it will not work. taking a lead from the star ground, which only connects to earth when plugged in via the sleeve of your guitar cable plug, if ya go to the actual ground plane, it won't work. if ya go to "-9v" it will work.
if you try to take a wire from the ground plane directly and connect it to the star ground, same thing. will not work.
curiously, all the POTS grounds are connected (well, pin 3, leftermost from the back with the pins facing up) and that does connect to the ground plane. connecting them to the star ground? same freeking issue!!
the only place i can see ground connected as i'd expect is at the bottom of the two 10k resistors i made the voltage divider with, and of course all the places various parts of the circuit ground to.
obviously, once plugged in, the -9v and "ground" all connect to the star ground on the input jack.
but if ground is ground, why can't it be connected directly, and only work when its shorted to the -9 of the battery?
Quote
I see in your readings U1 pin 3 as 2.23v. That voltage will be coming in via the 10k resistor, not from the amp pin - so a voltage reading at the ground end of that resistor might prove if it really does have that ground connected to supply -9v.
i will check when i get a chance! thanks jim!!
Quote
I got a warning - the fact that the CMOS amp may have an input "misbiased" could be an important part of the effect you hear. There a well known single amp full wave rectifier in the RCA CA4140 datasheet figure34 that has both pin 4 and pin3 to ground and deliberately referenced to 0v instead of 1/2V. The way that rectifier works absolutely relies on the 0v bias and the CMOS chips ability to handle an input that's more negative than the negative supply pin.
would that account for the cool/weird swelling in effect? i thought i was just overloading the hell out of it with no headroom lol
mucho tweakage later, and with thanks to Jack Orman for his suggestions, its a little further along...
modified the front end to a big muff pi style stage, messed with the feedback loop of the second opamp some, and, well, this is where i'm at so far.
i'm digging it a lot more than the stock circuit... but still got a ways to go.
the octave side is crazy and sick and outta control in a good way.
i gotta try and make sure i get it right and draw it up, changed the bias trimmer to a fixed 10k resistor.
but basically for the b to c feedback resistor, ended up with a 50k trimmer in series with a 130k resistor. there's a definite sweet spot ya gotta hit that varies with the q's. this wanted 187.5 k according to my shitty meter.
q was a 2n4401, didn't check hFE
ditch the snubber on q1.
make the b to ground resistor in the voltage divider 33k.
input cap 100n, e to ground resistor 100r.
that perks up the fuzz some.
on the second opamp, changed the 10k feedback loop resistor to a 100k trimmer.
its noisy but fun in a good way.
all a balancing act.
this thing is MADE to be driven by a fuzzface. wait til it gets to the feedback parts.
its very synthy at some settings, envelope responsive at others. a bass cut in the guitar makes it almost auto wah-ish.
still gotta long way to go, but... as a work in progress... check it out, yo
https://www.youtube.com/watch?v=qgsZMgUhNC8&feature=youtu.be
With the conversion to a single 9v battery, you have to watch where the grounds are going. I believe this should work:
(https://i.postimg.cc/tTR6gK18/jimi1.jpg) (https://postimages.org/)
regards, Jack
ps: Thanks for the shout-out in the vid!
its an honor to be able to do so, jack!
at this point, i need a break ;)
but i will try it again with your ideas and see what happens.
i am really digging the weirdness of this thing at this point.
sometimes it sounds like it has a delay on, or a phaser or something! ;)
i tried it, couldn't get it happening.
this thing is weird. ;)
more revisions.. stay tuned
Slightly revised for clarity:
(https://i.postimg.cc/rmSmq3P4/jimi2.jpg) (https://postimages.org/)
regards, Jack (https://postimages.org/)
thanks jack!!!
i did try messing with it last nite, i may have messed it up tho as i have the grounds for all the pots going to the star ground on the input jack.
i tried rewiring it so pin4 of the two chips was fed the 4.5v from the junction of the divider and 33uF cap, but it wouldn't fire at all... i'm assuming thats cuz the grounds for the fuzz and octave pots weren't going to the half voltage maybe?
i DO have another board, so i'll try building it up as suggested... easier to do now than it is on what i have so far.
i will try n shoot a bit more video of it as it stands now... i switched to a different q, something from the 2sc series, i can't remember which (had to twist a couple legs) but it brought the fuzz to life. the octave side i think i have ok now, the noise issues i had i believe were from subsonic noise getting frequency shifted up a bit... changed the 1uF coupling cap from the input stage to 47n, attenuating the lows really made a difference. the whole thing is now a decent amount above unity gain, but the octave part is still kinda low in comparison to the fuzz part.
it actually sounds a bit better than it did in the video posted yesterday... still crackin' at this nut, may take a while, but in the end it should go good on a pizza with bacon and pineapple.
as they say... stay tuned!!
and thanks for the help/advice!! you rock bro!
peace
where its at at this point. i had mistaken something somehow, it runs fine on 9 volts nothing spooky or mysterious but the cobwebs in the foggy abcesses of my mind....
this works. runs on 9 volts, sounds pretty good. i haven't added the caps in series with the fuzz and octave outs yet, but i think i should cuz i get a little interaction between pots sometimes that manifests in a little scratchiness during the end of the pots rotation.
'nother vid soon. gig tonite.
check it out
(https://i.postimg.cc/JsdsRb9S/double-hit-deux-rev-3-1.png) (https://postimg.cc/JsdsRb9S)
took it out last nite to try it thru my stage rig and the other guy's amps.
in tubes, it sounds great.
in solid state, YECH. NOT READY YET!!
so i plan on adding a bit of low pass filtering, its got some high squeaky parasitics happening with the line 6 i tried it thru... frequency doublers don't help lol
so a cap and resistor to ground to bleed off some of this ultra highs will work i think.
questions:
do ya think caps alone will be enough to isolate the mixer parts from each other?
there's a bit of crosstalk and i think some dc getting thru with the pots when some of them are maxxed.
i was thinking .47 for the fuzz side and .0047 for the octave side... but will they then interact with the "output" cap? i mean, caps in series act like resistors in parallel, so will this mean i will get the "average" of each pair of caps as an output cap?
is there a preferred <read: simple> way to decrease treble content, i'm thinking resistor and cap to ground to make a simple low pass filter to shelve off the parasitics... looking at the circuit, i'm thinking the two optimal places to do this would be either just after the voltage divider on the input stage, or at the junction of the 47n/10k input to the + input of u1... or is there a place ya think may work better?
slowly closing in on making this thing useful/useable. determined to turn its suck knob to a shine one! ;)
some pron
(https://i.postimg.cc/bsQCvRyZ/a.png) (https://postimg.cc/bsQCvRyZ)
(https://i.postimg.cc/5YC5RxjX/b.png) (https://postimg.cc/5YC5RxjX)
(https://i.postimg.cc/7fM94Y97/c.png) (https://postimg.cc/7fM94Y97)
(https://i.postimg.cc/BtFNhC1m/d.png) (https://postimg.cc/BtFNhC1m)
(https://i.postimg.cc/rDVJwXZH/e.png) (https://postimg.cc/rDVJwXZH)
(https://i.postimg.cc/64C0y9Nk/f.png) (https://postimg.cc/64C0y9Nk)
(https://i.postimg.cc/sB145Pr9/g.png) (https://postimg.cc/sB145Pr9)
(https://i.postimg.cc/N2v8hWrp/h.png) (https://postimg.cc/N2v8hWrp)
Try connecting the 10k on pin 3 of the first op amp to the 4.5v bias instead of to ground.
regards, Jack
i can most definitely try that. there's nothing actually hooked up to that 4.5 volt node!!
BUT if i disconnect it, the circuit gets very unstable and the fuzz sounds horrible.
i will try hooking it up there tonite when i get a chance and see what shakes out. thanks jack!! ;)
hey jack,
if yer still out there campin'
i tried hooking up pin 3 to the half voltage. no dice. i was looking at it when i realized the damn circuit as i had drawn it was wrong, and basically the top of the 10ks in the voltage divider was actually broken off down by the cap.
so i took it apart, and it still makes no sense at all. i drew it up carefully, and this is exactly what's on there, i can't make sense of it still, tho i seem to remember seeing something kinda similar once in an old kay 70x amp, where they used some caps in some pretty peculiar ways.
for all intents, the anode of the 33u <now 47u> was connected to b+. the bottom of the cap, the cathode, was connected directly to "ground" but also had a 10k resistor between the bottom of the cap and ground. if i disconnect this stuff, the circuit will run, but is wicked unstable. to me? this makes no sense... a cap to ground should read 0 v, but with the 10k resistor in parallel with the negative lead, i'm getting a little over 2 volts at that node!!
still playing with it... sadly, lost the freaky abilities it had in the video <can always mess up another one, i actually kept notes for a change> but it sounds a LOT better.
i added blocking caps to the outputs of the fuzz and octave... not a huge improvement as expected, but a bit less crosstalk when mixing the levels.
bringing down the 10 k to the - of u1 to 1k made a big difference... now i seem to have a decent amount of fuzz, treble, and sustain. so i gonna try it on the input of the other oa as well. i may go up in value a little bit, i think the sweet spot is around 2.5k.... we'll see
gonna try going to 1k with a 10k trim on the diodes in the octave part rather than having the 10k's and a 10k trimmer betwixt them. we'll see what happens.
i MAY try adding a simple boost/bazz fuss stage to the begining. or i may just do a p2p fuzzface. this thing sounds great with a fuzzface up front!
so up to rev 4. its getting a LOT closer to useable! stay tuned!
(https://i.postimg.cc/hJRzfxfD/double-hit-deux-rev-4-1.png) (https://postimg.cc/hJRzfxfD)
yeah....
it sounds cool now. BUT i figured out a couple issues, one of which is like, WAY too much dc on the output from the fuzz.. 2.4 something volts, seems excessive but i dunno.. it drives the amp pretty good, and has a nice raunchy overdrive to it.
but here's i think where things get weird.
there's that whole half voltage thing.
apparently some things CAN connect to that instead of ground, but SOME things MUST be earth grounded?
remember, i am an idiot. a 10 toed freak of a monkey with a breadboard and an occasional altitude problem. ;)
anyways, unless yer brave or insane, better leave this one to me til i sort this out. i believe the ground is somehow not what it appears to be... and i think the pots need to be grounded to the chassis better somehow, they connect to the star ground on the input jack.
i just don't expect to see almost three volts signal on the output of a fuzzbox with no signal passing thru it
:o
its almost like the whole thing is floating off that one freaking resistor coming off the - of the 33u cap (now 47u)...
i figured out the audio was leaking thru the cap charging off the positive rail and then discharging, which was giving me that way cool envelope sound in the video the other day, and i figured out the resistor in parallel with the - of the cap ws controlling the envelope time. i think in some way it was like ring modulating the signal with pollution on the ground rail or something. i have some kinda weird feedback loop thing going with it i need to figure out. it SOUNDS cool, but that kinda output seems like it should be worrysome.
so anyways, pretty much everything is actually "grounded" to that 2.13v spot at the node of the - cap and resistor to ground seen below. with the present 47uF cap and 27k resistor, its hanging at about 3.19 volts or so. the batterys kinda drained, so i expect it will go up a bit when i put it to a power supply.
(https://i.postimg.cc/YhDWQHNh/snip.png) (https://postimg.cc/YhDWQHNh)
this is where i think i got it @#$%ed up. it works, but like i said, its gotta lotta juice on the output, even after adding blocking caps, cuz the "ground" is actually somehow more like a negative rail, i am definitely not understanding this one at all at all.
all the stuff circled i assumed went to "ground" actually goes, somehow, to that 3.xx volt tap on the power supply.
the chassis appears to be grounded, but now thinking about it i better check from the neg of the power jack to ground to see if there's voltage. i bet its 3.19volts.
so unless i'm completley off base and out of my mind, this thing should probably be shelved, yes? just from a safety viewpoint?
seriously, is this thing gonna destroy my amp?
:icon_eek: :icon_evil: :icon_exclaim: :icon_redface:
if i try to hook it up "normal" nothing works. wtfff
most recent variation. nod to Jack Orman from amz, i stole his muffer circuit pretty much and used it for the front end... doubled up on the diodes and slightly different values.. but this part of the circuit sounds like a good fuzz now. thanks bro!!
but MAN! we got issues... shit shouldn't even be able to work i would think at all!!!!
this is what i have at the moment. every triangle with a circle is reading that impossible 3 volt supply off the bottom of that freakin 47u cap.
pin 4 of both chips reads 0v. that i expect. but all the other places that should be "ground" read 3 volts. something weird going on i just can't seem to figure out!
(https://i.postimg.cc/bSsMdTyd/ddd-rev-5-1.png) (https://postimg.cc/bSsMdTyd)
be back with voltages later. they haven't really changed, other than bumping the 2.13v up to 3.20 or so.
it SOUNDS great, but "ground" is reading 3.20 volts, and i have 2.4volts dc hitting the output jack when this thing is engaged with no signal going into it. something wrong!!
how in hell can a shorted resistor be reading any voltage?
this is what i got powering it
(https://i.postimg.cc/YhDWQHNh/snip.png) (https://postimg.cc/YhDWQHNh)
if i remove the 2.7k resistor, or the cap, or lift the grounded part of the cap from earth, the whole thing stops working.
how can this possibly be?
i gotta redraw the schematic, and button up a couple weird details,... but... its alive
i am such a dumbfugginidyot!!
so like, i been messing with this and messing with it, going batshit crazy trying to figure out what's wrong, right?
@#$% @#$% @#$% @#$%ity @#$% me!
i had the pots all on the same ground bus
and had that grounded to the "ground" on the board
which was actually that couple volts offset on the low side of that cap.
once i disconnected it and reconnected it to the star ground on the input jack, the fuzz was back in business, and better than it was cuz no more freekin dc.
i gotta do some more stuff to it, but thats what i did. i had insulation over it and didn't even realize what i did one of them bleary eyed 3am "time to solder" after a nite rabble rousing at the local pub n snout. nice.
so so far, all's well. the power supply is still wack, but it works, sounds good, and no dc. i'll take it as a win. ;)
oh....
and i was thinking... just something to ponder...
if a simple wire link is considered to be one ohm for all intents in some circuits
having that cap hooked up like that... i THImK... may work like this...
two resistances in parallel... 27k, and 1r...
well in math, anything divided by 1 is itself, right?
so 27000 divided by 1 = 27000, right?
so it can't be a short in this case, even tho it SHOULD be, right?
the - side of the cap is usually the outer foil shield.. if ya use electros for coupling caps, and touch the top of them, sometimes they'll buzz or hum cuz the shielding on the outside isn't connected to ground. but the shielding IS connected to the - lead of the cap.
so effectively, we're grounding the shield of the cap, and floating it above the negative rail with the 27000 ohm resistor in parallel with the 1 ohm one. the one ohm one, of course, being the negative lead of the cap, connected to the shielding of the cap and grounding it for less noise.
27k divided by 1 is still 27k, right?
as above, so below?
trickle down... oh, never mind...
;)
its the only way i can see this working, and it IS working and SHOULDN't be...
does that make any sense at all?
i DO remember seeing this done at black cat on their vibes to keep hum and noise down.. i was like... weird.. in that case, they had ground straps to the shields of some of the caps or something like that.
this may be a similar application, and man, i'd love folks thoughts on that one. ;)
anyways, i'll post the final last weird little tweaks to it tomorrow or tuesday, after a week of being an idiot looking at this thing i need a nights sleep ;)
https://www.diystompboxes.com/pedals/FAQ.html
Under Vref
yeah, i know, but that does not work in this, lol.
i tried extensive variations of power supplies, the only other way to get it to fire was to run two 100u caps with their cathodes tied together to ground, + or 1 to 9v, + of the other to -9v. it STILL needed the leak resistor to ground to function.
it will pass audio with a voltage divider, but it won't fuzz.
i been on this thing like white on rice for days trying to suss out how it could work, the math doesn't lie... 27000 divided by 1 is always gonna be 27000 bro ;)
and its the only way this thing will fire... it WANTS a bipolar 9v supply, 9v + and 9v- with
"ground" in the middle
if it looks like a duck, and it quacks like a duck....
it can't be an aardvark, right? :icon_mrgreen:
ok, that last feverish thought couldn't work. parallel resistances don't work like dividing numbers. even if they did, it couldn't work right.
still scratching my head, but think i figured it out. i was mistaking what would actually by vcc for ground.
from another post:
pinky don' be knowin bouts no ones or twos or kemzars of resistance ;)
still trying to wrap my mind around how the heck this thing is working.
the negative lead of the cap is most definitely going to the ground plane, "between" pos and neg. this plain reads around 3 volts now.
the positive side of the cap <now 100u> goes to the b+
the negative side goes to the "half" voltage ground plane between the two power rails
a resistor comes off that mid point on the cathode/ground side of the cap and goes to the actual -9v ground coming from the star ground.
at the junction of the resistor and cap cathode, is the 3 volt voltage. its not "ground" its something floating between the rails. i think.
so we got -9v, or ground
we got /+9v or vb
and we got "virtual ground" which is offset from "actual ground <-9 v>" by about 3 volts... close to half voltage.
before the star ground connected -9 v/ground to the board.
i had mistakenly thought the mid voltage was ground, not a mid voltage... hey, everything "grounded" to it, right?
but everything SHOULDN't have .... when i moved the ground point for the three volume pots to the input jack star ground instead of where it had been, it worked. when investigating that, i found that a little blob of solder on the second part of the fuzz/oct footswitch was actually shorting to the ground lead for the led's... thats what was letting the dc into the output signal.. again, my bad and a cheap mistake ;)
so in reality, -9v is ground. +9v is vb. the mid point, leaking off between ground and the cathode of that cap is where the 3v is coming from. its gotta be.
sorry, just trying to wrap my head around what was making this thing tick... now it sounds pretty good, and seems to be working. i'll take that as a win, and hopefully get some video of it soon too.
so, does that make sense? i think me mistaking the midpoint for ground is what @#$%ed me up.
of course, the bloody @#$%ing ground IS connected directly to this midpoint as well, by a jumper, still makes no sense... but... hey... :o
lol
i need a week on a mountaintop with some mycelia-ey goodness methinks 8)
does this explanation work somehow maybe? only other thing my fwacktured widdle bwain can come up with....
ok, i see what i did wrong, and why i was pulling my hair out.
this i believe is it, and works really well like this. its weird, but it works!
i had definitely confused ground with the vcc "half-ish" voltage
on the board, they are actually jumpered together... i thought. turned out that jumper was just for pin 4 of the opamps. go figure. i apologize for so much wasted bandwidth on my stupidity. ;) but maybe it will help some other moron like me some day. probably my OWN moronic ass, even.
anyways.. drawing rev 6, should be the charm, works great and sounds pretty good!!
(https://i.postimg.cc/jCjbVsQM/ddd-rev-6-1.png) (https://postimg.cc/jCjbVsQM)
in the end, the last schematic is good, other than choosing a .33u cap for the input cap.
its still a little gated, but its not too bad... compared to what it WAS, a lot better.
i think so, anyways... but, hey!! wtf do i know!!!! ;)
here ya go... styuuuuuuuuuupid pedal trick for the double hit deux, part deux
the smell of #fuzzygoodness
https://www.youtube.com/watch?v=M57uD8vKA6M&feature=youtu.be
usual les paul variant into my princeton, kick on a SSOD and a bit of echo here and there.. but ya should be able to get a good idea of how it sounds. rock on! stay fuzzy!
never able to leave well enough alone, i did some changes again.
5089 for q1
ne5532 for u1
ca3140 for u2
made the rectifier part diode clippers for each side, 1 ge diode feeding one ge diode clipper x2
increased the coupling cap to the second stage to 4.7u
now the octave and fuzz are much closer in volume.
may still play with it a little bit tho... never done. you know how it is ;)
Hey PinkJimiPhoton,
I know this is an old thread but I am working on the same Graymark Double Fuzz kit you posted about. I have it all together and I dig it but the one problem is the fuzz side is too quiet. I was wondering if you came across a fix for this? I went through the thread but it gets pretty hairy. It seems like there is a clean signal mixed much louder in with the fuzz. I can hear the clean coming through the fuzz, sort of. Otherwise I'm fine with the two battery situation but I get where you're coming from with the sustain/gating decay problem. Did you ever settle on a good fix for that? Hope you are well and I enjoyed the thread and your video. Any new vids or audio of the pedal as it ended up?
Thanks,
_Shawn