Balancing feedback loop clipping diodes amplitude?

[culturejam]

I will be the lone voice of dissent here and say that it does make a difference in the sound (not just the volume).

Take a typical Rat circuit, for example. The sound of LED clippers is not the same as silicon diodes. There is less compression (and thus sustain) with LEDs, and the conduction "knee" is more abrupt both off and on. Silicon diodes give a more "distortion" because they are clamping down a lot tighter on the op amp's output. If you correct for volume differences, the difference is sustain and clipping threshold (aka "dynamics") is apparent. Go ahead and give it the old Pepsi challenge. Make two marks near the volume pot where the two sets of diodes have the same output. Switch diode sets and move the volume pot to keep the two volumes the same.

If they don't sound different to you, then this will be first time ever that I heard something that wasn't ragingly obvious to others.    I have the least golden ears of anyone building pedals (ever).

[chromesphere]

Culturejam, if you say so, then I'm believing it! I think I might run a looper through a couple of settings and do an exact recording just to settle it (for myself) once and for all!
Paul

[midwayfair]

I will be the lone voice of dissent here and say that it does make a difference in the sound (not just the volume).

Take a typical Rat circuit, for example. The sound of LED clippers is not the same as silicon diodes. There is less compression (and thus sustain) with LEDs, and the conduction "knee" is more abrupt both off and on. Silicon diodes give a more "distortion" because they are clamping down a lot tighter on the op amp's output. If you correct for volume differences, the difference is sustain and clipping threshold (aka "dynamics") is apparent. Go ahead and give it the old Pepsi challenge. Make two marks near the volume pot where the two sets of diodes have the same output. Switch diode sets and move the volume pot to keep the two volumes the same.

If they don't sound different to you, then this will be first time ever that I heard something that wasn't ragingly obvious to others.    I have the least golden ears of anyone building pedals (ever).

Are you also correcting for gain differences? Are you saying that LEDs would be different from silicon diodes when the ratio of gain:Fv is the same?

You're right that silicon diodes are faster than LEDs, but LEDs are still pretty fast -- they're fast enough to switch an H11F1 to fully on, which is half a millisecond.

[culturejam]

Are you also correcting for gain differences? Are you saying that LEDs would be different from silicon diodes when the ratio of gain:Fv is the same?

All I'm saying is that if I match the volume output between LEDs and 1N914s in a Rat, it seems to me that the silicon diodes produce more sustain and compression.

I haven't tested on a scope or done any math or read an RG Keen articles on the topic. So maybe I'm fooling myself.

[midwayfair]

Are you also correcting for gain differences? Are you saying that LEDs would be different from silicon diodes when the ratio of gain:Fv is the same?

All I'm saying is that if I match the volume output between LEDs and 1N914s in a Rat, it seems to me that the silicon diodes produce more sustain and compression.

I haven't tested on a scope or done any math or read an RG Keen articles on the topic. So maybe I'm fooling myself.

You're not fooling yourself, but output volume is post-clipping. Gain is pre-clipping. As long as your amp isn't out of headroom, LEDs will have a larger maximum volume (but a lower maximum amount of clipping).

[culturejam]

I guess I'm misunderstand the discussion. I thought everyone was saying that other than output volume, there is no difference between any type of diode clipping in any circumstance.

I don't recall ever looking at diodes to change op amp gain.

[midwayfair]

I guess I'm misunderstand the discussion. I thought everyone was saying that other than output volume, there is no difference between any type of diode clipping in any circumstance.

I don't recall ever looking at diodes to change op amp gain.

I think I'm communicating this badly, but I don't know how else to explain it.

Anyway, I think the op's solution needs some sort of resistor in series with the volume pot on the clipping switch, or to mess around with the 100K on the output.

[blearyeyes]

Seems like the only answer is to set up the output volume to match. Leaving the clipping gain stage intact.