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I don't know a lot about EE, and this might not be the best place to ask, but I have a really basic question. I'm thinking about cutting an RCA to 3.5mm cable in half and inserting a pot for volume adjustment (it goes from TV to bluetooth transmitter). If that would work then what kind of pot would be best, and could I add another pot for right-channel adjustment? I was thinking that a concentric pot might be able to simplify things (one is better than two). I'd buy a premade cable that does what I want, but I don't think it exists. Any advice would be appreciated.

I'll draw a diagram and update my picture, if needed.

RCA-3.5mm

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Since humans perceive loudness logarithmically, it would be best to use a logarithmic trim pot to adjust volume. If you want to control two channels simultaneously and symmetrically, use a two-gang logarithmic potentiometer.

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  • \$\begingroup\$ Thank you for your answer, but I want the right-channel to be a an adjustable fraction/percentage of the master volume, and I don't see how a two-gang pot can do that without additonial parts (I'd like to keep things as simple as possible). \$\endgroup\$ – spiff Dec 28 '20 at 4:41
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    \$\begingroup\$ In that case, use a one-gang log pot on the right channel and just let the left channel pass through. \$\endgroup\$ – Hunter Morris Dec 28 '20 at 4:55
  • \$\begingroup\$ You're right: That's probably the simplest way to do it. Controlling the right-channel is all I need to do. But then, I thought, why not add a master volume control? And I don't think a two-gang pot will do what I want.. \$\endgroup\$ – spiff Dec 28 '20 at 5:03
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    \$\begingroup\$ You can certainly get away with a linear pot and it will work fine... you will just lose precision at low volumes and find that it jumps from zero to loud much more quickly than with a log pot, which is why parts marketed as "audio pots" and the knobs on a guitar are all log. \$\endgroup\$ – Hunter Morris Dec 28 '20 at 23:44
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    \$\begingroup\$ A concentric pot sounds like a good, compact answer! Plenty of cheap ones on eBay. If you want maximum audio quality (minimum noise) then a conductive plastic potentiometer is about as good as it gets, but it's probably overkill at 10x the cost... \$\endgroup\$ – Hunter Morris Dec 28 '20 at 23:50

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