Tech21 double drive - clipping curiosity?

[thelonious]

opposed and in series.

Ah. I had missed the opposed part. Great explanation, btw!

[slacker]

but the two Zeners running at 9V might not add any audible clipping with certain op amps. At 9v supply, you're likely to hit the power rails on many common op amps on at least one side before you get to 4V.

That's probably why they used a TLC2262 for that stage, that will get pretty close to the rails so the diodes will clip first, like you say something like a TL072 wouldn't work there as it would clip at a lower level than the diodes.

I thought the whole point was to only have half the waveform being clipped in that stage? With hard opamp clipping in the previous stage taking care of the other half of the wave?

No, that was just what I said based on what the first schematic showed, that is what that circuit would do. If the circuit is like Drboogey describes then the first stage is asymmetric clipping and the second stage does much lighter symmetric clipping.