No clipping diodes but still distortion ?!

[jeroen_verbeeck]

Hey, I wired my clipping diodes to a breadboard today for 'on the fly tweaking' instead of soldering/desoldering everytime.
I thought I'd give it a spin without any diodes in. I would have thought the distortion would be gone, no clipping, only volume control and tone control. But the weird thing is, the distortion is still there, and it doesn't sound that different than with all of them in.
I can add diodes to make it sound different, but still the basic sound of the pedal stays.

What is the cause of this ?

I took the red ones out, the blue ones seem irrelevant to me, how about those green ones ?
How can I make this pedal behave ?

Here's the schematic

[bioroids]

The Green and Blue diodes are irrelevant to the sound, but they have to be there. They form part of the switching and power supply circuits, don't take them out.

Luck

Miguel

[jeroen_verbeeck]

I was kida thinking the same thing. Howcome it's distorting then ?
Which other parts could be responsible for this ?

[amz-fx]

I thought I'd give it a spin without any diodes in. I would have thought the distortion would be gone, no clipping, only volume control and tone control. But the weird thing is, the distortion is still there, and it doesn't sound that different than with all of them in.
I can add diodes to make it sound different, but still the basic sound of the pedal stays.

Because Q22 is a booster driving the discrete opamp made from Q16-17-18-19 and the combined gain is larger than the voltage swing possible using the 9v power supply...  it can only swing ~8v pk-pk and the gain is trying to make the signal larger than that, so it is clipping.

Make R54 larger to lower the gain of the opamp....  try 10k and see if that works at low gain settings of the DIST control.

regards, Jack

[WGTP]

IMHO op amps contribute more distortion to circuits with diodes than they get credit for.  Is that why this one has a discrete op amp?