Fulldrive Comp Cut Question.

[JakeFuzz]

So it is easy to understand that lifting the clipping diodes out of a TS style circuit will make the effect into a clean booster (until you start clipping the second gain stage opamp). But what on earth does the comp cut mode in the Fulldrive do with that switched path to the second gain stage output?  Can anyone explain this to me? It seems sort of like a compression circuit where the output is effecting the gain of the first stage.

I ask because I am building a Menatone Red Snapper clone for someone and they wanted a clean boost option. This is one of the best clean boosts I have heard so I was hoping I could extend this concept to fit the RS.

[stecykmi]

pretty sure it's just "simple" feedback. i don't think compressor-type gain reduction has anything to do with it. it just looks a little funny because it uses feedback across multiple gain stages.

[JakeFuzz]

pretty sure it's just "simple" feedback. i don't think compressor-type gain reduction has anything to do with it. it just looks a little funny because it uses feedback across multiple gain stages.

I see, I have never seen a feedback loop between gain stages like that. Do you know what purpose this serves? I don't see any problems just implementing this exact thing in the Red Snapper, I just want to know how it works before I start using it.

[stecykmi]

i think you can treat the two gain stages as one if you were going to make a block diagram of the circuit. I think it was only implemented in two stages because it separates the clipping stage from the filter stage (which is usually a good idea, since you usually want filtering done after the clipping).


note that i'm not familiar with the red snapper so i can't really comment on it in any way.

[JakeFuzz]

Right, been reading up on "global feedback". I am pretty sure this design uses it to prevent op-amp distortion when the clipping diodes are lifted, this also fixes the global gain (above a certain local gain of the first stage), which follows how my FD2 behaves.