presence ala. peavey

[Andy Le Blanc]

I had a conversation with a guy at a jam about the presence and resonance
controls on his peavey...... that got me to look into the circuit......

now its just as one would expect...... a 5k (4.7K) resistor at the end
of a long tailed inverter with a cap(s) going to ground controled by a pot.
the resonance is a 1M pot in series with a small (.0068) cap in the feedback
feed to introduce a bit of phase shift and color the responce.... etc.....
all have been used before and there are many examples in many differnt amps
and makers...etc.....

but the peavey circuit uses an electrolytic cap to couple these to the top of the
5k resistor....... its a 22/25v with the positive lead connected to the bottom of the inverter ......

why?........ does it provide a bias?...... a phase lead?.....or lag?