freestompboxes.org

I just got this on my bench yesterday... already traced!
It's a very nice sounding distortion. Lots of gain and a very use-able.
The numbers on the chip are sanded off, but it has the pinout of a common quad opamp. My guess is that it's a TL074; it has the sound I hear from that series. This is a very good sounding distortion. I wish they were easier to get in the U.S.

And here is the schematic: I think if I were to build one of these myself, I would just use a single JFET for the input buffer and then need only a dual opamp. That would open up more possibilities for swapping chips too.
I would also use shielded wire for the input. This one has trouble with sometimes squealing if you turn the output high because of how close the wires are to one another.
True bypass mod would probably be a good idea too if you don't normally run a buffered signal path.

Nice work Soul - Your bench is becoming a production line, churning out the reverses!

Looks interesting. And I agree about the buffer. It's a shame to waste op-amp stages like that, and it would be cool to be able to have a bigger selection of chips to swap.

I don't get the function of R3

R10 what is that for? R3 as posted by Dirk what is that for? R1 might be better between R2 and pin3. The bypass wire should be better going to pin1 of the buffer.

Hey, I didn't design the thing, I'm only reporting my findings!

I agree with everything you guys have said... especially R10 - that one is completely pointless!
With R3, maybe the designer was wanting to simulate the loading of a common Source buffer with a 10k source resistance... but yeah, why? Maybe there was an original prototype that was built that way instead of using a quad opamp, and they wanted to be absolutely certain nothing changed in the sound when they switched it to being built with the quad?
I think the main reason for using the quad opamp is just to save on parts, probably saves a little money too.
But, woah... these things are 24,000 Yen!

I was just having some fun.
The only "good" reason I can think of for R10 is to "hard" shunt the signal to ground so it does not bleed into the path in bypass due to the switch used or layout.

Do you hear a click in the speaker when switching this effect in and out, I cal about 3ma for the LED 9VDC-1.7VDC/2.2K and the LED supply only has C7 .01uf and the internal resistance of the battery, this causes about a 3ma step in the power supply current , maybe a 100uf for C7.

The R10 the 100 ohm might cause a step in the output if the 10uf is leaky and the level is closer to max, heavy and level are the DC path to ground for the leakage current in C5.

Drew up a vero layout. Currently unverified.

There was an issue with vref network on my previous layout. That's now fixed, and here's the corrected layout. Not verified yet, but should be ok....

I built this one a few days ago, and I'm not getting the extreme volume level that so many builders have written about. The 39nf and 100pf caps are the only substituted components in my build - would either of those have an effect on output level? I have almost no audible signal before level is around noon, and it has to go past 2 o'clock to reach or exceed the volume level of the dry signal. I love the tone and pick sensitivity from this pedal, but I know I'm not getting the volume I should expect. I've checked all soldering and component placements, and all of the traces between rows are clean. I appreciate any help or suggestions.

Regards,

-Rob

mirosol wrote: ↑21 Mar 2013, 16:06 There was an issue with vref network on my previous layout. That's now fixed, and here's the corrected layout. Not verified yet, but should be ok....

Hello! I made the jawbreaker from this schematic and it doesn't work correctly. the sound is very horrible, not very loud, and when the gain pot is all the way down, the sound feels broken. Can you help me please? maybe something in this schematic was wrong

Thanks!