Capacitors In Parallel With Clipping Diodes

[Paul Marossy]

There is one pedal mod I have done where a 0.001uF capacitor is placed in parallel with an LED acting as a clipping diode in an opamp feedback loop. Can anyone tell me what affect this is supposed to have? Is that supposed to smooth out the clipping a little bit?

[aron]

Yes, check out:

http://geofex.com/Article_Folders/TStech/tsxtech.htm

The small 51pf capacitor across the diodes acts to soften the "corners" of the clipped waveform somewhat

and more...

[Paul Marossy]

Thanks! I thought that was the case, but I wanted to check to be sure. I'm going to read that GEO article now. 

[teemuk]

It's a low-pass filter.

The small 51pf capacitor across the diodes acts to soften the "corners" of the clipped waveform somewhat

Which is an effect of the low-pass filter. The sharper the "corner" of a clipped wavew the more higher frequency harmonics there are present in the signal.

[Paul Marossy]

It's a low-pass filter.

The small 51pf capacitor across the diodes acts to soften the "corners" of the clipped waveform somewhat

Which is an effect of the low-pass filter. The sharper the "corner" of a clipped wavew the more higher frequency harmonics there are present in the signal.

Cool, that will get me exactly what I am trying to achieve.