Amp design - opinions please

[Nick Ellingworth]

The trick is to not let the smoke out.

Actually, if you want low power consumption, stay away from op/amps etc.  The lowest power circuits around are the ones that you have control over.  Simple common emitter circuits for the pre-amp and a totem pole mosfet output stage will likely yield the best battey life.

BTW, are you using all those batteries to get a two rail supply?  If so, with discrete circuits you won't need a negative rail if you do it right.

I'm going for +18v not +/-9v. Looking at the power consumption if I use decent rechargeable batteries (probably lithium) I should easily get several hours use out of the amp before a recharge is needed. Battery life isn't part of the specification only 'battery powered' so even if it only lasted 5 minutes I would be complying with the spec.