Wouldn't there be an example of that technique here in the P10 preamp?JR. wrote:Yes I do not appreciate caps in series with Rg, but if you put two caps between the feedback network and gain stage - inputs they don't need to be as large as in series with Rg . You will need another pair of caps in series with the gain stage outputs and a separate feedback resistor for DC feedback. Since the entire feedback net is no longer in the DC path, no more scratch or clicks.
I've played with such circuits in Jurassic times. But the extra caps in the feedback network make the circuit a higher order LF filter and its difficult to avoid serious peaking on some gain settings.
If you've successfully used this, please post a sketch or some clue on how you did it.
Going back to what Olaf is trying to accomplish is a way to make the bias resistors very large for common mode signals using bootstrap while also injecting servo correction and having those resistors not lower Rcm.
My hunch is the only capacitors desired are the 2u2 films at the input with a very high Rcm so they don't degrade CMRR.
I'm still thinking about this...