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DIY Stompboxes => Building your own stompbox => Topic started by: RDV on April 27, 2004, 04:06:35 PM

Title: Heavy Metal Pedal Prototype
Post by: RDV on April 27, 2004, 04:06:35 PM
My first stab at designing and partially tested.  :shock:
Willed it to work!
Thanks Alf, & R.G. for hints and parametric circuit respectively.

(http://img54.photobucket.com/albums/v165/rickydon/Heavy_Metal_Pedal.gif)

Regards

RDV
Title: Heavy Metal Pedal Prototype
Post by: David on April 27, 2004, 04:27:40 PM
Hmmm...

FIVE op-amps and 2 stages of hard diode clipping, huh?  Where is your overdrive taking place?  If this thing works, I'll bet it'll scream!
Title: Heavy Metal Pedal Prototype
Post by: Paul Marossy on April 27, 2004, 05:16:11 PM
Looks interesting. Hard clipping in two spots, eh? If it were me, I might use one of those diodes pairs in the first opamp's feedback loop and keep the other ones at the output of the second opamp.

The parametric EQ thing looks like a cool idea. Is the opamp at the end intended to be an output buffer, or to compensate for the tone control section?

Maybe someone here can breadboard it and tell us how it works?! I would, but I just don't have the time...
Title: Kool !!!
Post by: petemoore on April 27, 2004, 05:19:51 PM
I'm strongly inclined to want to try that Parametric Bass Notch booster on some already made clipping devices.
 The Concept certainly makes sense.
 I don't quite follow how it works though...does the bottom OA/filter...N/M...How does it work, basically...?
Title: Heavy Metal Pedal Prototype
Post by: spongebob on April 27, 2004, 05:26:25 PM
I'm sure the second opamp needs a resistor/cap to ground (or Vb?) from the inverting input, like on the first opamp. How much gain is the second stage supposed to have?

And the diode clipping sections have +Vb DC offset, not sure if this would work. I think I will draw this beast up in SPICE and see how it behaves!
Title: Heavy Metal Pedal Prototype
Post by: RDV on April 27, 2004, 05:29:00 PM
http://www.massenburg.com/cgi-bin/ml/parametric.html
Title: Heavy Metal Pedal Prototype
Post by: will on April 27, 2004, 07:48:51 PM
Hi RDV,

Quote from: spongebob
And the diode clipping sections have +Vb DC offset, not sure if this would work. I think I will draw this beast up in SPICE and see how it behaves!

Spongebob is correct, The 1st set of diodes need to be connected to Vb or you need to add another coupling cap just after the diodes. Otherwise 1/2 your signal will be totally clipped.

I wonder if it would be interesting to put the parametric eq before the clipping.

A big tonal component of the distortion is the opamps, based on MXR Dist+ experience. You might consider temporarily replacing the 100K in the feedback loop of the 2nd opamp stage with a 500K trimpot. Then you can play with the gain of the second stage until you are happy with the sound.

Good luck!

Regards,
Will
Title: Heavy Metal Pedal Prototype
Post by: Mark Hammer on April 27, 2004, 08:38:01 PM
Note that the large amount of gain in the first clipping stage will peg the level close to whatever is the maximum signal permitted by the diodes.  Part of what that means is that even a modest amount of gain in stage 2 will "reclip".  So why limit yourself to Si diodes?  Stick in a pair of red LEDs instead of the diode trio and you will still get the benefits of a second clipping stage but will harvest a much heftier output level for punishing your amp and adding a "third clipping stage".  Worst case, stick in a single LED and a pair of Si diodes to maintain your asymmetrical clipping with a higher overall threshold.

Note that the 56pf cap in stage 1 limits HF rolloff at around 2.8khz, and the 330pf cap in the second stage limits HF rolloff at around 4.8khz.  Note that the .001uf cap you have in parallel with the second set of diodes rolls off high end around 16khz.  If you were not adjusting the tone downstream, I would agree with your choice of stage 2 rolloff, but the various rolloffs seem to be at cross purposes here.  

Given the reticence in your comments, this is obviously a first stab at a design using building blocks from other pedals.  You are to be congratulated for taking that step, and I imagine it feels VERY good...as it should.  On the other hand, what works just great in isolation in one pedal may conflict with something that also works great in isolation in another pedal.

So here are some suggestions.  I'm a big fan of cascaded rolloffs but for a design intent on catering to metal tastes, you don't want to roll off too much too soon.  So, drop that first feedback cap down to 33pf for a rolloff at 4.8khz.  Of course the clipping will add harmonic content beyond this point, but the idea is that you don't want too many harmonics of upper harmonics early in the game.  The cap in parallel with the diodes can stay just to keep these high gain stages from doing something foolish like oscillating.  

For stage 2, drop the feedback cap down to 220pf for a 7.2khz rolloff.  That will keep things sane but still permit some sizzle if you want it.  The .001 cap in parallel with the second set of diodes can go.  It really isn't doing anything terribly constructive, although note that when the tone pot is minimized to zero ohms, that cap and the tone cap parallel to form a .0043uf capacitance which forms a lowpass filter with the 10k resistor immediately preceding the diodes with a rolloff of 3.7khz.

Clearly, the .001 cap and .0033 cap aren't doing a whole lot of tonal changing, and my guess is that your tone control currently works largely as a "defizz" control, rather than a serious treble-altering device.  So, t'wer I, I would omit the second .001 cap, and replace the 10k tone pot with a 50k pot and 2.2k resistor in series.  This will provide a max treble rolloff at around 22khz (essentially no rolloff to speak of) and a min treble rolloff around 945hz, which will produce a nice round sound.  You can even stick in a 3900pf cap for a rolloff range of 780hz - 18.5khz.  Since the other suggested cap changes will offer up more treble to start with, you'll notice the difference a LOT.

These changes (diodes and caps) in tandem with your bass boost/scoop control should be able to deliver a very nice broad range of tones from  gronky resonant grind to big-scoop searing metal.  

One final note, as the article at GEOFEX shows, you can make a gyrator section with a single transistor.  This means you can declutter the board by using a single quad op-amp or a pair of duals, and don't have to stick 5 op-amps on there.

Congrats.
Title: Heavy Metal Pedal Prototype
Post by: RDV on April 27, 2004, 10:45:12 PM
Mark:

Thank you for your kind comments. My purpose(besides trying to finally come up with something of my own) is trying to come up with a real grinding, heavy sound that I haven't yet found in my DIY builds so far. I feel that many have enough distortion, but not the right EQ. I should probably try your Chaos & Roseyray, but I want to do it myself(with help, of course :wink: ). I spent all night finishing & debugging my Easyvibe(which I'm naming "Bridge of Thighs" :P ), which I finally got done(cold solder joints on a cap kept it from phasing). I printed out your post & studied it & revised my schem. Oh, and I am just going to use a pair of duals.

I wouldn't try it out yet, everybody!! :P

Thanks Mark, Alf, & all.

Goodnight

RDV
Title: Heavy Metal Pedal Prototype
Post by: spongebob on April 28, 2004, 05:09:18 AM
Good morning!

I have just finished the circuit in LTSpice, here are some observations:

- A coupling cap (1uf or so) is needed right before the 100K input resistor at IC1b
- The EQ stage isn't working, the signal get's totally screwed up, I don't understand what's going on there anyway :cry:

Here are a few plots:

This is the input signal, 150mV sine wave, 333 Hz
(http://home.tiscali.de/krabbensaft/spice/1.gif)

This is after the first diode clipping stage, as seen by the noninverting input of the second opamp:
(http://home.tiscali.de/krabbensaft/spice/2.gif)

And that's the output of the second opamp, there's not much left of the original signal, probably this stage has too much gain right now.
(http://home.tiscali.de/krabbensaft/spice/3.gif)

And here is the frequency response plot (excluding the eq stage as it is not working correctly).
(http://home.tiscali.de/krabbensaft/spice/4.gif)

Can anyone advise on the EQ section? The signal goes completely out of whack there...
Title: Heavy Metal Pedal Prototype
Post by: RDV on April 28, 2004, 06:27:56 AM
Spongebob:

Which schem did you simulate? The original or the latest? Cause I've changed it 3 or 4 times since I originally put it up.

RDV
Title: Heavy Metal Pedal Prototype
Post by: spongebob on April 28, 2004, 09:12:00 AM
After looking at the geofex page I noticed that the last opamp only needs a 2k7 resistor from output to inverting input!  In addition, the EQ stage must be biased to Vref, so put a 100K / 1uF combo before the 2K7 resistor at the start of the EQ section.

Edit: You can grab the LTspice circuit file I made from here (http://home.tiscali.de/krabbensaft/spice/metal%20pedal.asc). If you don't have the potentiometer lib installed, unzip this (http://home.tiscali.de/krabbensaft/spice/ltspice_pot_addon.zip) file into your LTspice directory. LTspice itself is available for free from here (http://ltspice.linear.com/software/swcadiii.exe).
Title: Heavy Metal Pedal Prototype
Post by: Mark Hammer on April 28, 2004, 11:55:38 AM
RDV,

Nothing special about my two fuzz contributions except that they share double-clipping in common with yours and try to provide a broad range of sounds from a single 3-knob pedal.  I like them, but then I imagine we probably all like those things we feel we had a hand in dreaming up, even if all our "design" amounts to is adapting some stock things we saw while sifting through schematics on the busride home from work (nothing autobiographical about that :wink: ).

I guess the thing to remember about multi-stage clipping pedals is that they are signal-sculpting[/i] devices.  Clipping something twice is not just doing the same thing over again.  The signal received by the second stage is not the same thing as what the first stage got, either in terms of bandwidth or emphasis within that passband.  So the thing to guide one's thinking in terms of tweaking or shaping the circuit is to think in terms of "What am I working with *here*, at this point in the signal path?" , and conceptualize the entire effect as if it were several pedals under one chassis.  

This has implications for tone shaping, pre-emphasis, de-emphasis, level-setting, diode selection, etc.  For instance, suppose you stuck the gyrator/EQ section *between* the two clipping stages.  What are the implications?  For one thing, it would permit you to adjust the extent to which different parts of the spectrum double-clip.  So, goose the low end with the boost/cut control, and now even modest gain settings in the first stage will result in heavy clipping of certain parts of the spectrum, while leaving others with just a hint of dirt.  Conversely, notch out a band between the first and second clipping sections and not only have you changed the tonal balance, but you may have placed some parts of the spectrum well below some critical level needed for re-clipping. (While it occurs to me, some experimenting with what goes between transistor stages 2 and 3 on a Big Muff is worth thinking about, since it is the granddaddy of all double-clippers; "Tone - its not just for output anymore").  If you *want* that to happen (i.e., touch of dirt for most notes but serious overtones for selected notes, not unlike use of a wah), then one starts thinking about how much gain needs to be applied in stage 2 and what the sensible choices are for what the diodes need to be in order to set clipping threshold.

If one sticks a gyrator/EQ section *after* all the nastiness has occurred, then that control does not shape the quality of the clipping, or where the clipping occurs most, but rather shapes what part of the clipped signal you *hear* the most.  That's not good or bad, just a different outcome.  

If you've seen any of the schematics for the 600 or so distortion pedals that DOD and Ibanez have out (like the "American Super-Metal Disemboweller", the "Tinitis Driver", and the "Temporal Lobe Destroyer..XL" pedals -  :wink:  ), you may note that many of these have gyrator sections both before AND after a clipping section.  In some cases the gyrator section is fixed.  It may not strike you right away as a boost or cut because there are no pots, but one educated look and you immediately recognize the component configuration seen in your bass control subcircuit, just with fixed resistors mimicking the boost/cut control set in fixed position.  

Some of us have been waxing poetically about the virtues of combining preclip and post-clip EQ for years now.  Akai took it to the hilt with their pedal that had dual 7-band EQs, one before and one after the distortion stage.  Not a big seller if I remember correctly (which is probably why a few folks here picked one up cheap from MF or Zzounds or whoever had em on sale), probably because most players don't wanna feel like they're designing a house when twiddling fuzz knobs.  

Still, something that alters spectral balance along the way, at least in a simple and musically valid way, is a nice thing to have.  In your case, something like a one-switch-plus-pot pre-boost may be right up your alley.  That is, a frequency-sweepable gyrator circuit with preset boost.  One pot sets where the boost occurs between stages, and the other either engages the boost or lifts it.  If one had a 3-position on-both-on SPDT toggle, you could actually mimic the two extreme and middle positions of a pot for boost/flat/cut.  That, *PLUS* a treble rolloff and bass/mid boost cut control on the output, would provide extremely flexible tone shaping. and a pedal you'd never tire of.  Your existing design has 5 knobs/pots.  What I'm suggesting would make it 6 and a toggle switch.  If the inter-stage resonant boost and the post-clip boost are set to the same centre frequency, that will likely deliver ridiculously easy singing feedback for the note range you select.
Title: Heavy Metal Pedal Prototype
Post by: Ansil on April 28, 2004, 03:01:46 PM
hey rdv man  for asy clipping man with leds try using the standard red led on one side and using a larger different color on the other side.  i use a 3mm red and a 5mm green for most of my clipping there, and u can tell a difference. a lthought i like two green 5mm too..
Title: Heavy Metal Pedal Prototype
Post by: Paul Marossy on April 28, 2004, 03:56:20 PM
I've tried the green/red LED combination before. I think that it sounds pretty good.
Title: Heavy Metal Pedal Prototype
Post by: Ansil on April 28, 2004, 03:59:45 PM
Quote from: Paul MarossyI've tried the green/red LED combination before. I think that it sounds pretty good.

thanks... 100 people can't be wrong lol  well i guess they could look at the whole jim jones cult purple koolaid thing.. hmmmmm  never mind  :D
Title: Heavy Metal Pedal Prototype
Post by: RDV on April 28, 2004, 04:41:26 PM
O.K. I've implemented pretty much all the suggestions for improvement.

Will it work now?

I guess I'm gonna perf & see! :shock:

RDV
Title: Heavy Metal Pedal Prototype
Post by: Davide on April 28, 2004, 05:15:25 PM
it looks great :)!
if it works i'll build it immediately ! i swear !  :D

(i was going to try building a dod death metal pedal.. it will wait) :)
Title: Heavy Metal Pedal Prototype
Post by: Paul Marossy on April 28, 2004, 05:34:01 PM
"O.K. I've implemented pretty much all the suggestions for improvement.

Will it work now?

I guess I'm gonna perf & see!"


Cool. I am interested to know how it turns out.
Title: Heavy Metal Pedal Prototype
Post by: Brian Marshall on April 28, 2004, 05:50:39 PM
it will work.  the diodes go th vb, and so does the bias risistor.  as long as the cap is sufficiently large in the voltage divider.  47uf should work

Quote from: willHi RDV,

Quote from: spongebob
And the diode clipping sections have +Vb DC offset, not sure if this would work. I think I will draw this beast up in SPICE and see how it behaves!

Spongebob is correct, The 1st set of diodes need to be connected to Vb or you need to add another coupling cap just after the diodes. Otherwise 1/2 your signal will be totally clipped.

I wonder if it would be interesting to put the parametric eq before the clipping.

A big tonal component of the distortion is the opamps, based on MXR Dist+ experience. You might consider temporarily replacing the 100K in the feedback loop of the 2nd opamp stage with a 500K trimpot. Then you can play with the gain of the second stage until you are happy with the sound.

Good luck!

Regards,
Will
Title: This one's
Post by: petemoore on April 29, 2004, 01:40:43 AM
This one's piqueing my interest !!!
 Have a great build RDV !!!
Title: Heavy Metal Pedal Prototype
Post by: RDV on April 29, 2004, 04:14:50 PM
The schematic at the first of the post is what I hope will be the sinal folution...er, uh..final revision of this sucker! I'd suggest breadboarding cause I'm not 100% sure the parametric will work. I'm going to perf it this weekend(I hope) sometime & post another report then. Please, someone feel free to do it & post a report. I'm exausted, mentally. I haven't had an idle moment for a long time, please give utmost respect for those who design & build these things because they are working hard, believe me!

Regards

RDV
Title: Well...
Post by: petemoore on April 29, 2004, 04:47:18 PM
"Don't you AlreaDy Have Every type of Distortion known to mankind"???
 "Well...Yeahhh...all sept THiS one" !!!
  Take it Easy RDV...There'll be time tomorrow to drive yourself to the brink of exhaustion...[I keep telling myself this].
Title: 04/29/2004
Post by: petemoore on May 02, 2004, 03:34:06 PM
Has this version of the Heavy Metal Pedal been confirmed or tried yet?
 I'm thinking of trying it on perf, [no breadboard here] but wondering if it's been tried/tested yet.
 ??
Title: Re: 04/29/2004
Post by: RDV on May 02, 2004, 07:37:15 PM
Quote from: petemooreHas this version of the Heavy Metal Pedal been confirmed or tried yet?
 I'm thinking of trying it on perf, [no breadboard here] but wondering if it's been tried/tested yet.
 ??
I've not had a lot of time this weekend, but I'm off next weekend(no gig), so I should jump in head first. I've perfed the first section(before the parametric), but have yet to tackle the parametric.

Above was edited cause it was B.S. due to a stupid wiring mistake. It now is correct(see next post).


RDV
Title: Heavy Metal Pedal Prototype
Post by: RDV on May 02, 2004, 08:50:23 PM
I reviewed my wiring yet again on the first section, and imagine that, I made a mistake! :shock:  :?

I think the circuit is pretty happening all the way to the regular tone control(all I've built so far). This is a slow process for me cause I am not an electronics genius, just a regular guy with an idea that I think is good, and the drive to get it done(hopefully) in spite of my limitations.

Pete:

If you want to try it, go ahead, I know it works through the regular tone control @ least(and sounds pretty good too). It's real big and crunchy.

Regards

RDV
Title: Heavy Metal Pedal Prototype
Post by: ahermida on May 03, 2004, 07:46:24 AM
RDV:

    Please post some clips when you have a chance.

Alf
Title: Heavy Metal Pedal Prototype
Post by: RDV on May 03, 2004, 08:45:37 AM
Quote from: ahermidaRDV:

    Please post some clips when you have a chance.

Alf
I've already started adding the parametric section(got to get a 10k trim from RS today), so it will be a bit before it's finished. I don't really have website to host them from either. I've been hosting the pics from photobucket which is free.

Regards

RDV
Title: Heavy Metal Pedal Prototype
Post by: will on May 03, 2004, 10:30:28 AM
Hi Brian,

Quote from: Brian Marshallit will work.  the diodes go th vb, and so does the bias risistor.  as long as the cap is sufficiently large in the voltage divider.  47uf should work

I totally agree my comments don't apply to the corrected/updated schematic. It should work fine.  :)

I'm interested in hearing the results.

Regards,
Will
Title: OK...
Post by: petemoore on May 03, 2004, 11:35:38 AM
I tried the 'bottom section' of the schematic, the Gyrator circuit.
 What have I done? :shock:
 Seems to work!!! Very interesting Bass control, is the best I can do to describe it...what have I done? :?
 For me to begin to explain cause/effect ... technically/musicall, will take a little better understanding of what it is I've done. :idea:
 I can say from a simple 'what's it do' perspective...it does 'strange' things to the bass content that makes interesting use of the bass register on my modded DIST+., and that I've got it working. 8)
 I can not say it's a hybrid Metal Pedal, however, there is the increased bass content and definition [expecialy for how much more bass content there is], and that I played with it for a long time last night, trying different interesting sounding settings, making the DIST + much more metal'ish'.  :evil:
 At this point a scope would make the design aspect more interesting, and probably easier. :roll:
 In the absence of a scope, being able to tune where the top and bottom range of the frequency band starts getting cutoff might be interesting to tune by ear. :wink:
 I wouldn't know where even to start to change the frequency range of the simple parametric, I'm just starting to get an idea how the pots 'work' ... the 1 meg pots influece seems dependant on at least one of the two 10k pots settings..
 Very interesting what this does to the DIST+ sound, chosen for testing by default because it was right there.
 Anyway to summarize last nights endeavors, the Parametric is working, and does indeed seem to have a 'metallizing' effect on  a Distortion circuit.
 I was having good fun playing 'it' as is, a nice addidion to a DIST+, quite different than without it, and very fun to play. :D
Title: Re: OK...
Post by: RDV on May 03, 2004, 12:20:06 PM
Quote from: petemooreI tried the 'bottom section' of the schematic, the Gyrator circuit.
 What have I done? :shock:
 Seems to work!!! Very interesting Bass control, is the best I can do to describe it...what have I done? :?
 For me to begin to explain cause/effect ... technically/musicall, will take a little better understanding of what it is I've done. :idea:
 I can say from a simple 'what's it do' perspective...it does 'strange' things to the bass content that makes interesting use of the bass register on my modded DIST+., and that I've got it working. 8)
 I can not say it's a hybrid Metal Pedal, however, there is the increased bass content and definition [expecialy for how much more bass content there is], and that I played with it for a long time last night, trying different interesting sounding settings, making the DIST + much more metal'ish'.  :evil:
 At this point a scope would make the design aspect more interesting, and probably easier. :roll:
 In the absence of a scope, being able to tune where the top and bottom range of the frequency band starts getting cutoff might be interesting to tune by ear. :wink:
 I wouldn't know where even to start to change the frequency range of the simple parametric, I'm just starting to get an idea how the pots 'work' ... the 1 meg pots influece seems dependant on at least one of the two 10k pots settings..
 Very interesting what this does to the DIST+ sound, chosen for testing by default because it was right there.
 Anyway to summarize last nights endeavors, the Parametric is working, and does indeed seem to have a 'metallizing' effect on  a Distortion circuit.
 I was having good fun playing 'it' as is, a nice addidion to a DIST+, quite different than without it, and very fun to play. :D
I've built the front end, and you've built the ass end, and they both work, so I guess we can assume that the circuit works as drawn(by moi). I've got the parametric in progress, but not complete, cause I need a 10k trim for the resonance control. I'm gonna get one today from RS.

The parametric controls do this(in theory):
1.The 10k pot(labeled BASS) is pupposed to control the content of boost(resonant peak), or cut(notch) of the EQ.
2.The 10k trimpot(labeled resonance) is supposed to control the Q of the circuit(how wide an area the EQ effects).
3.The 1Meg pot(labeled BASS FREQUENCY) is supposed to control the frequency that the EQ effects from about 50hz to 500hz(I hope).

Boy! This is starting to get a bit exciting. HAH!

Now all we need is someone to work up a PCB for this monster!

RDV
Title: Re: OK...
Post by: ahermida on May 03, 2004, 06:13:49 PM
Quote from: petemooreI tried the 'bottom section' of the schematic, the Gyrator circuit.
 
 I can say from a simple 'what's it do' perspective...it does 'strange' things to the bass content that makes interesting use of the bass register on my modded DIST+., and that I've got it working. 8)
 I can not say it's a hybrid Metal Pedal, however, there is the increased bass content and definition [expecialy for how much more bass content there is], and that I played with it for a long time last night, trying different interesting sounding settings, making the DIST + much more metal'ish'.  :evil:
 


Petemoore:

     When I started working the low end of my pedal I felt the same way...the Parametric EQ brings some sort of presence to the sound that is not easy to describe.  Initially my EQ was developed as a standalone pedal to be placed after a distortion/OD unit, so when I turned it off I would notice something lacking from the distorted sound...as soon as I kicked it back in the pedal would come back to life.  The interesting thing is that you can tune it to your specific amp/cabinet to get the best performance.  Someone that tested the parametric  EQ standalone pedal told me "you don't know you need it until you turn it off and listen to a pedal by itself".  This person was using the EQ after a TS9.

Alf
Title: Heavy Metal Pedal Prototype
Post by: RDV on May 03, 2004, 10:29:49 PM
Update:

I had to shitcan the volume recovery stage and make it a plain buffer per R.G.'s schem. Making the last stage a gain stage made the circuit oscillate like nobody's business. Seems to work fine without it. Plenty of volume & gain. I again, can't crank up & really test it cause everybody's doing HHOOMMEEWWOORRKK, & trying to go to BBBEEEDDDD, & looking @ me like I'm an asshole. Nevermind I'm making a breakdown....er...breakthrough, yeah! that's it, a breakthrough(starts to laugh uncontrollably), but I digress. Being a responsible dad really sux sometimes!!

@ the limited volume & time I got to listen, it seems that the bass parametric section only boosts or goes back to flat, rather than notching, oh well. I didn't really want to notch much any way. I was looking to overcome the bass loss seemingly inherent in high gain designs, & I may have cracked it, but I'm not jumping to any conclusions just yet. :roll: More testing is needed.

I've updated the schem for those of you building along. It works for sure, I've got it in front of me & it works, quite how well I don't know, more changes may be in store.

If you are perfing along with me(or planning on it), the circuit fits well on one of those RS medium size boards with the two rails running down the middle(ideal for the 9v+ & the 4.5+ needed for OA circuits) with plenty of room to spare.

SPAM ALERT
Oh, by the way, if you need any of those 1uF film caps this circuit is loaded with, I got a bunch still left for cheap. .68uF, .47uF, .22uF, & 470k resistors too!

Regards

RDV
Title: Heavy Metal Pedal Prototype
Post by: strungout on May 04, 2004, 12:51:08 AM
Oy.

Well, I just breadboarded it a few hours ago. I got that oscillation thing :D playing with the pots/trims, I got some tremolo effect and changing the frequency was very reminiscent of old b-series alien movies  8). Yeah so, i got some problems with the "bass" section, but since you say it works well, I guess I must've screwed up a connection somewhere... I'm gonna try the new schem tomorrow. I do like the gain of it. keep it up :D

Ciao.

PS: oh, is it normal that it eats up the battery so quick?
Title: Notch
Post by: petemoore on May 04, 2004, 03:02:12 AM
Notch means...only a narrow band of frequencies 'gets through'?
 That's pretty much what I think I'm after...
  Rolling off highs, and limiting only a certain amount of lows say at input, would leave the band of freqs that are left in the midddle, but how sharp would the cutroff be?
 That said, some kind of curve on a bass peak filter [or is that the same thing?] would be worth experimenting with.
 Maybe  there's a way to tune a coil to produce a fairly narrow band bass eq peak...
  I'm pretty certain that's what I'm after if that semi narrow to narrow bass frequency band.
 The other post "PEQ" [Parametric EQ] tonight is about the experiments with and SD-1 [sounds like a very thick TS+ beyond]...Was a fun play no doubt. Kinda took some dialing, only tunes cool one way, but werth the monkeying to get there...didn't really sound like yer average widget...
Title: Heavy Metal Pedal Prototype
Post by: RDV on May 04, 2004, 06:20:15 AM
Quote from: strungoutI got that oscillation thing :D playing with the pots/trims, I got some tremolo effect and changing the frequency was very reminiscent of old b-series alien movies  8). Yeah so, i got some problems with the "bass" section, but since you say it works well, I guess I must've screwed up a connection somewhere... I'm gonna try the new schem tomorrow. I do like the gain of it. keep it up :D

Ciao.

PS: oh, is it normal that it eats up the battery so quick?
I got the B-movie tremolo & tunable oscillations too @ 1st. If you get rid of the stuff on the output stage to make it a plain buffer the oscillation should go away, but the eating batteries thing is a little scarier, you may have a short somewhere. Check for continuity where you shouldn't have it.

RDV
Title: Re: Notch
Post by: RDV on May 04, 2004, 06:23:42 AM
Quote from: petemooreNotch means...only a narrow band of frequencies 'gets through'?
 That's pretty much what I think I'm after...
  Rolling off highs, and limiting only a certain amount of lows say at input, would leave the band of freqs that are left in the midddle, but how sharp would the cutroff be?
 That said, some kind of curve on a bass peak filter [or is that the same thing?] would be worth experimenting with.
 Maybe  there's a way to tune a coil to produce a fairly narrow band bass eq peak...
  I'm pretty certain that's what I'm after if that semi narrow to narrow bass frequency band.
 The other post "PEQ" [Parametric EQ] tonight is about the experiments with and SD-1 [sounds like a very thick TS+ beyond]...Was a fun play no doubt. Kinda took some dialing, only tunes cool one way, but werth the monkeying to get there...didn't really sound like yer average widget...
Notch means a narrow band of cut frequency, though the Q control will widen it, I've got to bring in the big amp & try mine, as my Ruby doesn't have enough bass to fully hear the sweep.

RDV
Title: Heavy Metal Pedal Prototype
Post by: Torchy on May 04, 2004, 06:34:58 AM
So RDV, is the schematic at the start of this thread the final solution or is there an updated one ???
Title: Heavy Metal Pedal Prototype
Post by: RDV on May 04, 2004, 07:11:04 AM
Quote from: TorchySo RDV, is the schematic at the start of this thread the final solution or is there an updated one ???
The one at the beginning is the latest version. It works, as is, if you build it as pictured you will get sound and no oscillations & stuff. I'm still testing the prototype which I finished de-bugging last night. I'm @ work @ the dreaded day gig right now, so I can't do anything. It needs to be tested on an amp that's capable of a lot of potential low end so that aspect of the circuit can be heard. Time is not my friend.

Regards

RDV
Title: Heavy Metal Pedal Prototype
Post by: Torchy on May 04, 2004, 07:39:07 AM
Excellent - Im still learning about mods and tweaking so a proven schematic is a good starting point for me.

Excellent thread, Im learning so much from this forum :)
Title: Heavy Metal Pedal Prototype
Post by: strungout on May 04, 2004, 02:14:33 PM
Well, you were right...three times...three misconnection...geez what was I on...oh, yeah....

Everything works well now. I had a sort of gate effect at some point, which was pretty cool on the upper string but it killed the 3 lower ones. It's a really cool pedal. I like it when I palm mute on the lower strings and I still get the grinding you get on the upper strings, from the pick scratching the wrapping.

One thing tho, the tone 50k pot/trim affects the volume alot, anyone have an idea how to get around that? An explaination of why that happens would be cool too. Maybe I just wired something wrong again...

Great work, keep it up! Yoo can doo it! Run forest, run! And thnx :D

Ciao.
Title: Heavy Metal Pedal Prototype
Post by: RDV on May 04, 2004, 02:47:07 PM
Quote from: strungoutOne thing tho, the tone 50k pot/trim affects the volume alot, anyone have an idea how to get around that? An explaination of why that happens would be cool too.
It  affects the volume alot because of the amount of treble it rolls off. You could try taking out the resistor(2.2k) that follows the pot which would raise the rolloff frequency a bit, therefore reducing the volume rolloff, or even use a smaller pot like 25 or even 10k.

HTH

RDV