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Stereo Parametric Equalizer
This project is based off of the Sontec MEP250A 5 band EQ.
I've adapted it to use Blore-Edwards PZ style 23 step rotary switches but other switches or regular pots could be used as well.
I used the following references and resources when designing and tweaking this project:
Original Sontec MEP250A achematic gurtosey of Gyraf
The Don Classics 250EQ 500 series module
(I've built 4 f these and they are really really great)
Glass-Ware audio bipolar power supply
I used this power supply in my build rather than design my own. You can substitute for any decent bipolar power supply that provides +/- rails around 15V - or whatever you want to use for your opamps.
Igor's calculator for rotary switch resistor values:
Igor's Calcs GSheet Link
. I didn't like the rev. log taper on the Frequency switch so I added my own calculations here:
My GSheet Link
PCB render for reference: