wein bridge?

[Andy Le Blanc]

Any body mess around with a wein bridge for tone controls?
Seems like a 3 band passive EQ might be very usable.
Its just a pot, a couple caps and a resistor for each band.
It would be nice to have a couple bands of real mid control.
What should the freq. centers be? 2 band? 3 band? 4 band?

[selloutrr]

their are several calculator for this floating around the forum I'm sure someone will post a link.

from a usuable audio engineer's point of view My mid frequencies would be

4 BAND
260hz
310hz
500hz
800hz

3 BAND
260hz
500hz
720hz

2 BAND opt 1
500hz
800hz

2 BAND opt 2 (depending on where the Hi freq picks up)
260hz
600hz

[Andy Le Blanc]

I had the time this morning to play with it some more.
I rigged a 2 band, each filter is literally just a 1M vol pot with two caps
dressed series between the wiper and ground. The signal is taken off
between the two caps. Both caps are the same value, which determines the
filters frequency. Its very simple and it works pretty well.
The draw back is the insertion loss, which is pretty hefty.
I think that driving the circuit from a low impedance stage will help and
planning ahead for the insertion loss with a buffer stage is a must.

I used two 220p caps for the treble and a couple .01uf for the low.
The tone was alright, I could dial in just about any thing.
I think a 3 band with an appropriate gain structure could be very nice.