Geofex bootrapped twin T question...

[LiLFX]

Here is the schematic...

http://www.geofex.com/article_folders/eqs/twintee3.gif

If I wanted to use a bipolar power supply I'd omit the voltage divider and the 100K bias resistor on U1a, but what do I connect the end of the 50k pot to? Would I need to keep the voltage divider and apply the half supply voltage?

[GibsonGM]

I believe you would connect it to (signal..AC) ground, LilFX.   Right now it's "in the middle" of the signal's rise and fall (Vref), as it should be...if you use a bipolar supply, signal (AC) ground would be the same thing. 

Ex: +9 and -9V supply.  0V is your "Vref" for all intents and purposes; 1/2 of power supply.  So, anywhere calling for "Vb" or "Vref" would go to 0V.   

[LiLFX]

See..that's what I thought since your power supply is AC ground. I just wanted to make sure I wasn't smoking something.