Control volume w/ 1 pot for 2x TDA7297 amp modules

Oziam · Jun 3, 2015

Hi all,

I have 2 separate TDA7297 amp modules complete w/ B50K pots for volume control & I want to control volume for both simultaneously with one(master) 50K 6 pin rotary pot. Can I do this simply by connecting the back 3 pins from the Master pot to the back 3 pins of both amp-module pots & same for front pins?

Pommie · Jun 3, 2015

You just replace the two single pots with a dual gang pot.

Mike.

Oziam · Jun 3, 2015

The amp modules are 2 channel so the existing pot is a 6 pin, I want to have 4 channels controlled by 1 pot

Pommie · Jun 3, 2015

In that case, you need a 4 gang pot.

Mike.

Oziam · Jun 3, 2015

Thanks Mike, I didn't realize they existed.

Pommie · Jun 3, 2015

Assuming you're in Australia, Farnell stock a 10k 4 gang pot. https://au.element14.com/bi-technol...472?ost=potentiometer&categoryId=800000002962

Mike.

Oziam · Jun 3, 2015

Yep Queensland Australia, that's a pretty good price too.

I also found some at DigiKey

Wade Hassler · Jun 3, 2015

Don't know if it matters to you, but none of the Farnell and Digikey parts shown are both 50K and audio-taper.

audioguru · Jun 3, 2015

Wade Hassler said:
Don't know if it matters to you, but none of the Farnell and Digikey parts shown are both 50K and audio-taper.

50k is not needed, 10k or 20k will work fine since any audio sources can be loaded with it.

Oziam · Jun 3, 2015

Wade Hassler said:
Don't know if it matters to you, but none of the Farnell and Digikey parts shown are both 50K and audio-taper.

audioguru said:
50k is not needed, 10k or 20k will work fine since any audio sources can be loaded with it.

Oziam · Jun 3, 2015

Yes I did notice that Wade, thanks, as audioguru commented 10 or 20 k would work. Digikey have 1,10,20 & 50K Pro Audio series but nothing in stock so I would have to back order.
I actually managed to make a custom hack by joining two 50K dual gang together as one, syncing them was a bit fiddly but they are very close within 7% which is good enough for my purpose. Thanks to all for your help, much appreciated

crutschow · Jun 7, 2015

Wade Hassler said:
Don't know if it matters to you, but none of the Farnell and Digikey parts shown are both 50K and audio-taper.

A quasi audio-taper can be generated with a linear pot if a resistive load of about 15% of the pot resistance is added from the wiper to ground (for example a 15kΩ resistor for a 100kΩ pot).
It's not exact but it should work much better than a linear taper for volume control.

Control volume w/ 1 pot for 2x TDA7297 amp modules

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