Why buffer bias voltage?

[trjones1]

I'm making an MXR Microamp and I have an extra opamp not being used on my TL072.  What benefits would I get if I used it to buffer Vb?

[Mike Burgundy]

http://www.geofex.com/circuits/Biasnet.htm
hih

*edit* okay, that's a bit short, but it does say it all. Better operation because bias voltage is more stable (as in not dependant on current draw). Might not make a discernible difference in this circuit, but give it a go.

[alanlan]

The TL072 is a FET input op-amp so it doesn't draw any bias current anyway but even if you used a "normal" op-amp, I'd use the extra stage for something more exciting, like additional gain (if you really want it!) or tone control, extra buffered output etc.

[trjones1]

Ah yes, Geofex.  I've read that article a couple of times but I forgot that it talked about buffered Vb.

Alanian: I don't think I need any more gain out of the circuit, but an active tone control sounds like an interesting option.  I already have another Microamp that I've added a buffered dry output to, which is very useful.  Otherwise I would do that.  Thanks for the suggestions.