nned help with mark hammer's chaos

[Marcos - Munky]

I built it and liked it. I saw a Mark's post with some improvements to it, then I tried. They didn't worked for me, I got a lower volume (lower than the clean signal) and very treble sound. Then I tried to get back to the original circuit, but I got the same results. Here are the voltages:

Battery: 8.96V

Pin1: 4.16
Pin2: 3.9
Pin3: 2.27
Pin4: 0
Pin5: 3.7
Pin6: 4.16
Pin7: 4.16
Pin8: 8.33

IC is a TL072.

[Mark Hammer]

What specifically did you change?

[Marcos - Munky]

I changed the diodes in the second stage to a pair of leds and changed the second stage 100K resistor to a 330K one, then get everything back to the original values after test it.

[Mark Hammer]

Well, none of those changes should have produced what you describe, unless something got burnt/torn/shorted during the process, or unless you accidentally inserted both LEDs in the same orientation.

My guess is that something got "rearranged" during the upgrade.  Look for things like bent IC pins sitting under the chip (but above the socket), or solder bridges.

[Marcos - Munky]

Can burnt diodes make this effect? I think that maybe I burnt them.

[Mark Hammer]

Certainly if an LED is acting like a low-resistance path it can.  If all the components "worked", and a person simply stuck in a piece of wire across that 330k feedback resistor, the second op-amp stage become a unity gain stage.

The first stage pumps up the level considerably to make the first diode set clip, but the tone control also loses a lot of signal.  Perhaps enough to bring the level below the bypass level.  

Maybe there is your answer.