On Nov 21, 3:53*am, DaveC wrote:
I'd like to add a simple op amp-based tone control circuit to my preamp for
desktop speakers & sub that I'm modifying from stock.

It would really help to explain what you mean by that. 6" drivers in
wood cabs plus a 12" sub? Or 2.5" pc speakers plus a 4" sub? Very
different animals.


This is the simplest I found:

http://www.simplecircuitdiagram.com/2010/02/03/single-op-amp-tone-con...

(I have +/- supplies so I will be eliminating all coupling caps and changing
Vcc/2 to ground.)

What are the positives and negatives to this design?

As said, the odds are the freq response wont match what you want. A 5
band graphic equaliser would be better, and is pretty aesy to make.

Better circuit (yet simple)?

Thanks.

If you wanted simplest, the circuit can be far simpler if you use the
existing amp's nfb path to simply insert treble & bass boost controls.

Bass boost: Pot and C in parallel in the nfb path,
Treble boost: Pot and C in series from nfb path to ground, after a
resistor.


NT