can you use 3 or 4 diodes in parallel to ground for hard clipping?

[TimWaldvogel]

for instance basically doubling th hard clipping circuit on an average dist +

like


-----opamp-signal--------Diode2ground ----- inverted-diode-to-ground-----Diode2ground -----inverted-diode-to-ground----- output----------

[Quackzed]

you can, but only two of them will ever be operating. whichever of the 2 positive facing diodes to ground has the lowest clipping threshold will clip first,preventing the other from turning on, and whichever of the 2 negative facing diodes to ground that has the lowest threshold will do the same to the other negative facing diode... so if the first 2 back to back diodes have the lower thresholds, it will behave as though the other 2 higher threshold back to back diodes werent even there...the signal will be clipped before they get a chance to do anything...
if you wanted more clipping, you could choose 2 diodes that will clip at half the voltage of the original diodes..
if originals were silicon dioides, you could replace them with germanium diodes and the signal will get clipped more, and as a consequence, the output volume will be lower due to its amplitude having been clipped more...

[PRR]

Paralleling identical diodes will not change the clipping function, except to lower it an insignificant amount (four diodes = 40mV change of clip-voltage, say from 0.6V to 0.56V).

It's actually amazingly hard to "sharpen" passive clippers.

[TimWaldvogel]

hmmm ok that makes since, i has anybody tried asymmetrical clipping with 2 diodes and 3 diodes? instead of the usual 2 to 1. i know the out put would be large and the gain would probably be lower. anybody try it out physically?

[BAARON]

Not in a dist+, but in other circuits, yes.  It's just slightly less asymmetrical, assuming all diodes are of the same type.  I like a 2:3 ratio.

[TimWaldvogel]

well for example what if i used one silicon 1n4001 and 3 leds on the other side in a tube screamer, does that defeat the purpose of the asymmetrical feeling?

[anchovie]

Three LEDs would be useless in a Tubescreamer, the sum of the forward voltages would be greater than the maximum signal swing from Vref to an op-amp rail. It would be the same as if you just had the silicon diode and nothing else on the other side. This would be very asymmetrical though.

I think you need to get some experiments going on a breadboard.

[dschwartz]

i think you can harden the clipping increasing the value of the resistor that feeds the diodes to ground. This resistor makes a voltage divider when the diode is "kinda" conducting and acting as a resistor. The bigger this resistor is, the harder the clipping..but keep in mind that it will also alter the impedance of the signal.