stereo graphic equallizer for TDA7297

[Ulysses874]

Hello everyone,
I'm just a beginner with electronics and I'm trying to build a portable stereo speaker system with a three band graphic equalizer. The amp chip is a TDA7297.
I'm struggling to build a stereo graphic equalizer with 3 potentiometers to connect to the TDA7297.
I found many schematics like this.

http://www.zen22142.zen.co.uk/Circuits/Audio/3bandton.gif

My problem is that all the schematics I found so far seem to be made just for one channel (mono) whereas I have a stereo signal coming from my source, thus I have two separate channels to control.
If I double this circuit diagram for the two channels, I'll end up having 6 potentiometers (3 for the Left and 3 for the right channel). Instead I want to control Left and right together with just one trimmer and having an EQ section with a total of three potentiometers.
Does anybody have a circuit diagram for a stereo 3 band EQ with JUST 3 trimmers?
Thank you

[Cozybuilder]

Have you considered using dual pots?

http://smallbear-electronics.mybigcommerce.com/alpha-dual-gang-16mm-solder-terminals-linear-audio/

[Granny Gremlin]

Exactly that ^

This is only a good idea if your signal is really stereo (you want to preserve the stereo image) vs 2 channel.  If 2 channel, (say dirty and clean) seperate controls for each channel will be very useful.

Another option, depending on the source, is to EQ it in mono before it becomes stereo.  Obviously if the source starts in stereo disregard this bit.

[PRR]

Welcome!

Most "stereo" is really two mono paths. For convenience and neatness, use dual pots as Russ and Gran say.

It IS possible to do stereo with single pots-- the pot makes a DC voltage which controls a chip with dual paths. See Canakit CK146. However note that it is out-of-stock.... this chip has not been made in many years. Offhand I do not recall the chip number.

EDIT -- not the same as the Cankit plan, but the TDA1524 chip does similar stuff. A project with plans can be found on an English store site.)

The one-chip solutions are usually bass/treble, not 3-band. They were developed for older car radios which could barely sport two tone knobs. Modern car radios get more elaborate chips but need a clik-clik-clik interface with a display screen to say what band you are messing with.