Jim Thompson wrote:

Eeyore wrote:

In response to various posts please find attached a mic amp which has seen
volume production in commercial equipment.

Feel free to ask any questions / criticise whatever.

Operating within 0.7V of the common-mode voltage spec troubles me.

0.7V ? That's loads ! It was thoroughly chjecked.


I'd bump up those 680 ohm resistors to say 2.2K, making the
common-mode operating point approximately -7V.

The 680R is to be honest a carry over from the previous style of design. With
that 2k2 you'd get close to cutting off the input devices with a very large
input signal.

Graham