[Possum]

I'm thinking of adding Jan's crossfeed circuit to my Szekeres amp (DC coupled with a gain stage). I remember Tomo telling me I might need to use a buffer before the crossfeed, and the circuit would be before the input of the amp's gain stage. Is this right? Would a buffer based on BUF634 be what I should be using, or is adding this going to do something else to the amp in terms of sound characteristics. I'll probably use a switch to select between a single crossfeed level and bypass (bypassing the buffer and crossfeed).

 

[Tomo]

Hey,

BUF634 may be too powerful and very unnecessary. Besides, you can get some gain from decent opamps like OPA132 etc.

Your case is very weird. Your gain stage and MOSFET follower stage cannot be separated so that you can insert crossfeeder btw them.

If I were you I would make the whole amplifier DC coupled with dual PSU. Then inserting crossfeeder is very simple.

As is, it is probably would not be optimal to add buffer. The rest of your amp is single PSU and the buffer you intend to use require dual PSU. Personally, I don't like to be unnecessarily crafty about designs. I like straight forward and simple designs. So I don't prefer operating dual opamps with single PSUs.

Tomo

 

[rickcr42]

Well I use the "natural Bass" passive crossfeed straight in before my "original" single supply Szekeres amp and works just fine (some slight attenuation)

unless you are feeding it with a source with a very high impedance you do not need to buffer it

Rickster