Early 80s Distortion

[b-spot]

Thank you very much! The pedal works, and as you said it's lacking a hint of gain and is a little dark/flubby, but gives a nice fuzz-like tone.

[jymaze]

For more gain, change R5 to 100 ohms. It should tighten the bass a little bit too.

To correct the tonal balance without changing C3, you can change R7 to 2.2k. Then you should have the same voicing as the original schematic.

[b-spot]

Thanks for the insight. I added a switch that removes C3 from the circuit, it works well as a bright/dark switch.
I switched R5 to 150 ohms and now it gives me a full on overdrive when the gain is at 0 and a very square-wave sort of "vex" fuzz sound when the gain is at 10. I'm very happy with this pedal and all the sounds in-between.

[Manfred]

I make a little mod as follows.
The resistor R7 has an free lead now connected to the new terminal "R7".
So it is possible now to hook in a potentiometer to set total resistance to the diodes D3,D4.
The stripboard is bit longer now.

and a very square-wave sort of "vex" fuzz sound when the gain is at 10

I guess that the OP-amp is overdriven in that case, to avoid that it is recommend to use 18V supply voltage
for more headroom by using a charge pump circuit for eq.

[friedtransistor]

Old old old thread, I know, but one thing was bothering me. D1 and D2 are facing the same direction, whereas they should be facing opposite of each other.

[Manfred]

Hi friedtransistor,

Thank you for pointing out that mistake to me.

The corrected layouts as follows.

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