Author Topic: Just built this - Gain problems  (Read 6245 times)


Just built this - Gain problems
« on: August 03, 2009, 09:26:44 AM »
Hi there,

Just built this using a selection of left over parts;

LM741 -> LM324 Quad (using just one amp on the chip)
C1 using 22nf instead of 10nf
R1 using 2 1M resistors to make a 2M resistor
C2 using a 22nf instead of a 47nf (have tried a 47nf but i think the cap was blown)
C6 using a 150uF instead of 100uF
C7 using 6.8uF instead of 10uF
C3 using 56pf instead of 25pF
C5 using 22nF instead of 10nF

The pedal produces some light distortion however it is not even slightly noticeable when playing through a guitar.

Also the gain pot has no affect whatsoever on the sound. I have plugged the pedal into my PC oscilloscope and have tried various things with the gain pot, including shorting it out, none of which had any affect.

Any suggestions?! The only main thing I have changed is the op amp to a LM324 but I wouldn't have thought it would make a huge difference?


  • Great Contributor!
  • ***
  • Posts: 490
  • Total likes: 1
  • They call me Mr. Pig... That or Aidan.
Re: Just built this - Gain problems
« Reply #1 on: August 03, 2009, 09:43:39 PM »
Hey Will, think you forgot to include the schematic and/or link...

Have a look at the debugging thread (sticky), and post back what you find...

[edit] just realised that this is in the "IC based overdrive" section, so that's probably the schematic!!

Second bit still applies though  ;)
« Last Edit: August 03, 2009, 09:45:28 PM by ACS »