Thoughts on this pedal?

Started by Transistor-Transistor, August 30, 2024, 07:36:39 PM

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Transistor-Transistor

As some of you may know I've been working on this overdrive/distortion for weeks upon weeks now. I think I finally finished it unless further testing reveals somethin'.



I love the body control. It's a modded Framus mid control. Turning it clockwise flattens out the eq and turning it counterclockwise scoops the low midrange. The freq switch makes it scoop a lot, or even more.
A bunch of you helped me with the bass drive control. I didn't realize how much it would affect the overall distortion until a few weeks ago. I liked it a lot  better than the fuzz face gain control I had been using, as this one is a whole lot less muddy at low drive settings.
Let me know what you think or if theres anything questionable/wrong/unnecessary about the schematic!

Atticus M
Why does man create? Is it man's purpose on earth to express himself, to bring form to thought, and to discover meaning in experience? Or is it just something to do when he's bored?
-Calvin, Calvin and Hobbes

amptramp

If you have built it and you like it, great!

One thing I would question about the design is that the collector of Q2 is held to within ± a germanium diode drop of the base.  There are designs that put a capacitor in series with the antiparallel diodes so the collector-to-base voltage is not as constrained.

The Big Muff uses 1 µF in series with the diodes to keep the diode activity strictly in the AC signal range.  This has the advantage of requiring more drive in the bass range of the signal to achieve clipping, so the fundamental content doesn't get clipped as much as higher frequencies, making the clipping lass muddy.

The output voltage is limited to ± one silicon voltage drop.  The diodes at the output have no capacitor to limit the high-frequency hash of diode conduction coming in suddenly at the extremes of output voltage.

It looks like a simple enough circuit to put on a prototyping board but you should leave enough space to add components for experimentation purposes.

Transistor-Transistor

Oh hey thanks I was actually just wondering how I could fix the high freq stuff, I decided to try it loud and I heard it and I was like ehhhehheh
I'll try the big muff thing you suggested to see how that sounds!
(I'm actually really glad you brought that up because there was a lot of muddiness too that I kinda haphazardly fixed with high pass filters which added to the other problem heh)
Why does man create? Is it man's purpose on earth to express himself, to bring form to thought, and to discover meaning in experience? Or is it just something to do when he's bored?
-Calvin, Calvin and Hobbes

Rob Strand

Quote from: Transistor-Transistor on August 30, 2024, 07:36:39 PMI love the body control. It's a modded Framus mid control. Turning it clockwise flattens out the eq and turning it counterclockwise scoops the low midrange. The freq switch makes it scoop a lot, or even more.
Are you sure the C7, C8 values are correct?  Probably won't work like variable mid notch (like Framus) with those part values.
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According to the water analogy of electricity, transistor leakage is caused by holes.

Transistor-Transistor

Quote from: Rob Strand on September 01, 2024, 06:39:55 PM
Quote from: Transistor-Transistor on August 30, 2024, 07:36:39 PMI love the body control. It's a modded Framus mid control. Turning it clockwise flattens out the eq and turning it counterclockwise scoops the low midrange. The freq switch makes it scoop a lot, or even more.
Are you sure the C7, C8 values are correct?  Probably won't work like variable mid notch (like Framus) with those part values.


Its very modded. It already has a set notch in this one and it scoops lows too
Why does man create? Is it man's purpose on earth to express himself, to bring form to thought, and to discover meaning in experience? Or is it just something to do when he's bored?
-Calvin, Calvin and Hobbes

Transistor-Transistor

So theres a weird buzzy crackle underneath high notes. Does anyone know why this is? Lowpass filtering doesn't help it
Why does man create? Is it man's purpose on earth to express himself, to bring form to thought, and to discover meaning in experience? Or is it just something to do when he's bored?
-Calvin, Calvin and Hobbes

Transistor-Transistor

Yeah I did all of amptramps suggestions and theres still this quietish crackle on the decay of high notes regardless of settings
Why does man create? Is it man's purpose on earth to express himself, to bring form to thought, and to discover meaning in experience? Or is it just something to do when he's bored?
-Calvin, Calvin and Hobbes

Rob Strand

Quote from: Transistor-Transistor on September 01, 2024, 09:16:01 PMYeah I did all of amptramps suggestions and theres still this quietish crackle on the decay of high notes regardless of settings

Not sure if this will fix it but when I looked at the design originally I had a beef with C3 in series with C5 connecting across the output of the buffer Q1.  It's possible this connection can cause oscillation.

You can maneuver around it without affecting the tone by moving R5.


Send:     . .- .-. - .... / - --- / --. --- .-. -
According to the water analogy of electricity, transistor leakage is caused by holes.

Transistor-Transistor

I just tried both positions and it made it worse. I up and removed C5 and the crackle is still there so I don't think its an oscillation issue but the problem may be around that soft clipping stage?
Why does man create? Is it man's purpose on earth to express himself, to bring form to thought, and to discover meaning in experience? Or is it just something to do when he's bored?
-Calvin, Calvin and Hobbes

antonis

Try to move NFB clipping configuration from Q2 Collector to R6/R7 junction..
"I'm getting older while being taught all the time" Solon the Athenian..
"I don't mind  being taught all the time but I do mind a lot getting old" Antonis the Thessalonian..

Transistor-Transistor

#10
Hey that worked! Thanks!
Why does man create? Is it man's purpose on earth to express himself, to bring form to thought, and to discover meaning in experience? Or is it just something to do when he's bored?
-Calvin, Calvin and Hobbes

antonis

"I'm getting older while being taught all the time" Solon the Athenian..
"I don't mind  being taught all the time but I do mind a lot getting old" Antonis the Thessalonian..

Transistor-Transistor

Uh oh its back now (or has always been there faintly and I just noticed)
Its very very faint now but its still noticeable at loud volumes
Why does man create? Is it man's purpose on earth to express himself, to bring form to thought, and to discover meaning in experience? Or is it just something to do when he's bored?
-Calvin, Calvin and Hobbes

antonis

#13
Delete R6..
(by  shorting it..)

edit: FWIW, Q3 is badly biased..
(its Collector current is strongly dependent on particular VBE drop..)
I'd make R16 470k and R14 2k2, adding a 10 to 22 μF cap in parallel (like C4/R8) in case of high gain retention wish.. :icon_wink:
"I'm getting older while being taught all the time" Solon the Athenian..
"I don't mind  being taught all the time but I do mind a lot getting old" Antonis the Thessalonian..

Transistor-Transistor

Oh that made it sound way better! 10uf was a little too high gain for me so I switched it to 3.3uf and I think it sounds great
Why does man create? Is it man's purpose on earth to express himself, to bring form to thought, and to discover meaning in experience? Or is it just something to do when he's bored?
-Calvin, Calvin and Hobbes

Transistor-Transistor

Its back  :icon_evil:
This time it actually literally was nonexistent until five minutes ago. Should I assume it's something to do with the breadboard?
Why does man create? Is it man's purpose on earth to express himself, to bring form to thought, and to discover meaning in experience? Or is it just something to do when he's bored?
-Calvin, Calvin and Hobbes

Transistor-Transistor

Actually I'm starting to think I could get a similar sound with less parts with a LM386 based circuit. What do you all think?
Why does man create? Is it man's purpose on earth to express himself, to bring form to thought, and to discover meaning in experience? Or is it just something to do when he's bored?
-Calvin, Calvin and Hobbes

aron

I don't know what your overdrive sounds like but I don't think the LM386 would sound the same.

antonis

Could you plz post a schematic of your final design..??
"I'm getting older while being taught all the time" Solon the Athenian..
"I don't mind  being taught all the time but I do mind a lot getting old" Antonis the Thessalonian..

ElectricDruid

Quote from: Transistor-Transistor on September 03, 2024, 09:30:48 PMIts back  :icon_evil:
This time it actually literally was nonexistent until five minutes ago. Should I assume it's something to do with the breadboard?
Random crackling that appears and disappears without apparently having anything to do with what you just did?

Yep, sounds like breadboard gremlins to me!!

If you want to know for sure, build the circuit in a more solid format and see what happens. I honestly don't know of any other way to check.