Very interested in this!

Maybe it's some kind of Superfuzz unit (left) with a section of their Whetstone phaser (right) ?

Maybe a dumb question, but why does this schematic use a 2x6 rotary and not a 2x5? Hey there! My supplier sells 2x6 only. But on rotaries like these there is a metal ring with a tip. By adjusting the tip in the correct hole, you simply stops the rotations. So the standard has 6 positions, but you c...

well, i've checked everything and tried a zillion different transistors for the MPSA06 'scoop' circuit (i socketed that transistor) and it still has about a 10% or less of the volume than the other 4 settings. if i could just get it to be the same as the others, i'd probably be happy with it. Weird...

Hey Johnk, thanks for your feedbacks!! Mine has the tone control like made in the layout (the 2nd one you're referring about). As I told in a previous post, one can try different pin wirings on the tone control depending on what is needed. In the last layout acts mostly like it's supposed to do, but...

Johnk, I didn't experience any of the low output issues. Are you sure you did the very same of the schem? The only way you can have low output is by forgetting one of the input capacitors on the circuits (the 100 nf for example where the signal enters in the squarewave section of the circuitry) or o...

My bad!! There was a mistake and the pedal seemed to work properly due to the ultra-heavy amount of gain. I corrected a couple issues and now it works. Treat the SCOOP transistor (NPN MPSA06) like a PNP - that means collector to GND. Squarewave section TL072 has pin 3 and 5 connected to Vref. Check ...

Done and tested, I'd say verified.
That's my take on the DBA Apocalypse, reversed from an original a friend owns.

Hope it helps.
Enjoy.

Updated files are here

This is a BMP with Whizzer Mods: https://www.youtube.com/watch?v=v8jXlTuUvQs After 10 minutes of playing, I decided to restore it to the standard Black Russian BMP...now I'm happy :) Have you traced the mods? I am curious on what could make a big muff sound in such a strange way... No clipping diod...

Can someone explain me what is the purpose of D4 at the collector of the second transistor? I can't really think of anything except for dropping the voltage by 0,7v

Correct me if I'm wrong but wouldn't lowering the value of those resistors give Q1 and Q2 a much hotter bias? Do you suppose the designer is using them as boosts or to contribute to the distortion in some way? I've read in a couple of earlier posts that these changes seemed "arbitrary" bu...

c3, c7 the diodes and r5 all goes to ground.

TLC2262 to my ears clips more gracefully than most of the other opamps. Dunno it's because it's a MOS opamp or because of it's abysmal slew rate (0.35 to 0.55 Volt per millisecond, according to the datasheet).

The biasing resistor of the first buffer is only 150k, this thing has a pretty low input impedence. Do you think that's a deliberate choice or just a mistake by the "designer"?

Aside from the buffers, is R5 just a positive feedback resistor? Also the frist opamp max gain is around 500x, so this thing should have a massive amount of distortion going on, instead is just a medium gain overdrive. Am i missing something?

Now this sounds interesting. When you talk about negative feedback, do you mean the base-collector cap and resistor pairs? I'm just heading home now to try out a couple of ideas on this circuit. First is a dual-gang pot acting as a pair of emitter resistor AC bypass pots on the two clipping stages ...

Hey Nocentelli, have you tried using some negative feedback to tame the beast? bet you can get some low gain smooth tone if you filter some high end and super low end in the feedback network.

Low input impedance is probably the key for a good sound here. Can somebody try a buffer in front of it? I predict that there would me much more treble coming out of this little circuit.

my first guess is that you've put a wrong value resistor in the mixing stage (the two 10k resistors before the output).

Greg wrote:Why would he socket those resistors ??

Probably he just messed up, the socket was for the IC but he put it in the wrong place.
I'm gonna try to trace a schematic for this, it shouldn't be that hard.

Thank you juanro for this project. Have you already tried this pedal after a buffered one? I'm not sure on this, but the input impedance seems quite low and that could affect the fixation performances in a pedal chain.