TL072 Pre-amp with 3 band EQ

[nikolozj]

Hi everybody,

I've just built this pre-amp, called "Tonemeder", found on this website here with it's sample tests and stuff...
http://www.runoffgroove.com/tonemender.html
Here's the schematics they have on website:


when I tested it, it was going mute when I would turn MID and BASS potentiometers all the way...
so this is fixed version of diagram:


works fine now...... BUT!!

I would like to modify it more, instead of simple switches of LOW MID and HI MID, I want to have individual potentiometers doing that....

can anyone suggest how that would work?

[Pollinator95]

Do you mean the Mid shift switches? I imagine you could use a voltage divider, the same way as a volume control. Assuming that works, it would probably alter the frequency response a bit because of the added resistance.

Edit: BTW, those switches are both halves of a DPST switch, so they're thrown at the same time. You'd need a ganged pot for what I said.

[PRR]

> mute when I would turn MID and BASS potentiometers all the way...

It is an exact (almost) copy of a classic Fender tone control, which also "went dead" if all three knobs were turned-down.

So don't turn all the knobs all the way down.

Shifting the cap-values is not easily done with a pot. Consider a rotary switch.