[sdiy] Full wave rectifier for audio

[Seb Francis]

Hi,

I'm working on a full wave rectifier (as the front end of a noise gate 
level detector), but I'm having trouble finding a simple circuit that 
works well.  I'd like it to be done with max 2 opamps plus a few extra 
components.  Anyone know of a suitable circuit that will work over a 
wide signal range (i.e. from less than a diode drop up to ~10Vptp)?

The nearest I have so far is this:
http://burnit.co.uk/sdiy/stuff/full_wave_rectifier.gif
(it intentionally has a gain of 2, but this isn't absolutely necessary)

But the problem with this is the circuit itself tends to slightly 
positively bias the input signal resulting in the positive halves of the 
wave being slightly higher than the negative halves.  This effect is 
dependent on the impedance of the driving circuit - if I slap an opamp 
voltage follower on the input the problem goes away .. but I don't 
really want to use another opamp if I can help it.

Any ideas how to fix this circuit, or is there another circuit that will 
do what I want?

Seb