What do you think of this preamp design?

It looks overly complex... A very competent solid state line stage could easily be built with about 1/3 the components. The op-amp in the feedback loop looks to me like an outright design problem...

The ability to take a balanced or single-ended source is shared by all preamps with a differential input.

We are trying to have it ready for RMAF... at any rate, like the MP-1, the remote for the MP-3 will be retrofit to any earlier MP-3.

Dracule1, you don't need RCA outputs on a preamp. What you need is XLR inputs on an amp. There is a way to do that such that both phases of the signal can be processed by the amp, without using a transformer and without changing the character of the amp.

If this sounds a little mysterious, its not- the technique is very simple. However, its not in common use in audio, which has always amazed me. I have a set of 45-based P-P amps at home that use a single-ended traditional driver circuit. Normally an amp like this would use only an RCA input, like a Dyna ST-70 or something like that. But I have been using this technique with this amp for several years, so it has an XLR input as well and the amp is processing both phases of the signal, even though the actual circuitry is the same as it was before.

This might be a matter for a different thread...

Kirkus, if that's a servo, as long as it is handled properly I would expect it to work fine. The schematic really did not offer timing data, and there should be some integration at the output of the opamp else the servo will not work correctly. We use servos in our preamps too as our outputs are direct-coupled. I agree his English could be better...

Dracule1, I was not proposing that the amp be modified by anyone in particular, and it is certainly work that the manufacturer could easily do. If you *did* decide that this is something you were interested, I would be happy to talk to whomever made your amp so they would know how to do the mod.