I'm working on a guitar pedal distortion circuit and I've been experimenting with introducing diode clipping into the signal. My question is, how can I increase the influence this diode clipping has on the final sound? Right now it makes a very small change in the sound and i want to hear the diode clipping more.

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  • \$\begingroup\$ Please don't redefine terms. If "diode clipping volume" is an industry term then I'll just wince and move on. If it's not, use "influence" or "effect", or whatever the industry term is. \$\endgroup\$ – TimWescott Jun 13 '19 at 17:25

IC1 is a voltage amplifier. It's job (so it thinks) is to put a voltage on its output that is a bigger version of the voltage on its inputs. R14 is a high enough resistance that IC1 can push it around at will -- basically, you've hooked a Mac truck up to a wet noodle, and you're wondering why the wet noodle isn't affecting the truck's behavior.

Try moving the common terminal of S3 to the other side of R9. If you like what happens, you may also wish to experiment with reducing the resistance of R14.

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  • \$\begingroup\$ Thanks for the insight Tim, I'm just getting started with things, I've been reading theory but also plugging things together to see how things interact. Any 'Getting Started' resources you'd recommend? So far I've worked through a few books -- Make : Electronics and Practical Electronics for Inventors is my main reference book. \$\endgroup\$ – greyBow Jun 13 '19 at 19:53
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    \$\begingroup\$ "The Art of Electronics" by Horowitz & Hill. Get the latest edition you can afford, but any will do. It's basically about practical electronics for non-electronics majors, so it should be helpful. \$\endgroup\$ – TimWescott Jun 13 '19 at 19:59
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    \$\begingroup\$ As a simple hack exchange C5 and R9. After that you might need to change the values of R14 and the other resistors in the 'diode clipping' circuit. \$\endgroup\$ – HarryH Jun 13 '19 at 22:37

Your diode clipper is in the wrong place to be effective. It should be after R9 not before it.


It is hard to determine what audio source you are using (rhythm guitar?) how distortion is created and how much. Perhaps you can experiment with GarageBand or Audacity and define a sound byte and post it then show how it was created in order to emulate it. enter image description here Play an undistorted recording and then modify it with this and other options and post the unmodified and modified tracks in an audio, then show settings. We'll try to decipher the transfer function needed.

It seems you started by copying something from some unknown site and now want to improve it, except we cannot hear or see anything specific.

There are a few basic mechanisms for creating distortion;

  • expansion ( done by your depletion mode FET biased in the off state)
  • compression ( done by diodes with soft limiting series resistors)
  • spectral shaped distortion ( shaping harmonics with filters )
  • asymmetric distortion with one polarity have more gain than the other.
  • even order harmonics
  • odd order harmonics (square waves)
  • all harmonics
  • slight positive feedback
  • echo and feedback

The LM386 is a low gain amplifier 20 to 200 and thus limited flexibility.

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  • \$\begingroup\$ Thank you for detailing the distortion mechanisms, that's really helpful. I didn't think of using recording software as a starting point. Thank you! \$\endgroup\$ – greyBow Jun 13 '19 at 19:54

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