Removing Clipping Diode???

[pedal pusher]

Hey all,

If one removes a clipping diode all together from the circuit, does this end the signal path killing the sound? It would leave an open circuit and I am wondering what the outcome would be? Does the circuit NEED a diode in place say a 1N914, an LED, or a 1N4148?
Thanks

[s.r.v.]

just jumper it

[zachomega]

Depending on how the diode is wired in, jumpering it could kill all of the signal or greatly reduce gain. 

Be careful with removing diodes though, sometimes they are used to bias other parts. 

What effect are we talking about particularly?

-Zach

[Zben3129]

Without the schematic, its nigh impossible to say,

For example:

Indicator LED - Removing has no effect on signal path, jumping could have adverse effects on +9v
Clipping diode in feedback loop: Removing all lowers gain, jumping all removed diode clipping and increases opamp clipping
Hard clipping diode - Removing will remove any diode clipping, jumping will generally kill signal path, as it is a direct short to ground
Polarity protection diode: Not neccesary, just used for, well, protection.

So, you can see, it all depends on the circuit. As a general note, however, any time you jump something in the signal path directly to ground, you're gonna have no more signal.

Zach

[pedal pusher]

Specifically it would be the MT-2 Boss pedal. It would be the D3 and/or D4 not sure as I don't have the pedal in front of me yet. But now that I think about it, tell me if this makes sense. There must be more than one diode, in parallel, creating the clipping/tone and by removing one of them, it doesn't kill the circuit, it just give it a different sound as now it is going through 1 less diode (the one removed). Does this make sense?

[5thumbs]

D3 and D4 are the hard clipping diodes in the MT-2.  If you remove one of them, you'll only be clipping 1/2 of the waveform, which will give you less distortion/fizz/fuzz/saturation/"whatever you like to call it".  It will also give you a boost in volume, as you are no longer hard-limiting the voltage of that half of the signal waveform.

D3 and D4 are wired parallel to the signal path, not in series.  This means that you can remove one or both of them without killing the output signal of the pedal.  You'll just alter or remove the clipping/distortion from the pedal, but you may end up with distortion further down the signal path (i.e., op amp distortion in the downstream op amp for the tone circuit as a result of the greatly increased signal gain...or even preamp distortion in your amplifier for the same reason.)

If you have something like the BOSS HM-2 (which many don't these days), removing some of their clipping diodes would kill the signal, as they used a mix of hard clipping (parallel diodes to ground) and crossover distortion (opposing diodes in series with the audio signal).  If you remove the crossover distortion diodes, you'd have to replace them with jumpers to keep sound coming out of the pedal.

Hope that helps.  Good luck!

[pedal pusher]

Yeah thanks, that's definatley what I was looking for.