[sdiy] Preamp Module

[George Kisslak]

Hello All,

I've been thinking of building an audio preamp module for my MOTM setup, to
hold me over until Paul releases his planned module.  A simple inverting-amp
and inverting-follower design is what I was thinking.  (I think I said that
right. :)  A variable gain control and an input impedance selection switch
would be bonus (but I don't know if I'm sharp enough to pull that off).
The input devices are: coil-pickup guitar, line-in, and piezoelectric
transducer.

So I'm wondering, which op-amp(s) might be best for this application?  I
know this is probably trivial to most of you, but I'm still ramping up the
learning curve.  I've seen OP275/285, LM833, TL081/71/51, and RC4558 used
successfully in various designs.  There are most likely others that could be
utilized as well.  I'm unsure in some cases why certain op-amps were chosen,
although probably due to cost and availability.  (I'm not too worried about
cost.)  I know that in one design, the 4558 was utilized in order to capture
the necessary sound characteristics.

I'm sure you each have your own opinions on this... I'm hoping you might
share them.  :)

George