If I go
> with 10K resistors for all the R in
> http://sub.allaboutcircuits.com/images/03046.png would I be ok using a
> 10K pot for the Rgain control? My read of the formulas is that as
> Rgain approaches 0, the gain increases. For 10K resistors and a 10K
> pot, minimum gain would be 2, and maximum would just go higher as I
> decrease the pot. Does that sound right? Will that be enough gain?

Typical gain you will need is 20 to 40 db.

Do not use a potentiometer where you suggested. Run your differential amp
at 20 db fixed gain, put the pot afterwards as a voltage divider, and
follow that with a single opamp with 20 db more gain.

Using input coupling capacitors gives you a small measure of protection
against DC into your opamps.

You do need to set a DC level on the inputs of the opamps - pull them down
with resistors. 10K is fine.

And load the mic with 1 or 2k.

Cheerful regards,

Bob

--
http://www.piclist.com hint: PICList Posts must start with ONE topic:
[PIC]:,[SX]:,[AVR]: ->uP ONLY! [EE]:,[OT]: ->Other [BUY]:,[AD]: ->Ads