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value of a potentiometer to attenuate amp inputs? Answered

I have three 'sources' of stereo audio fed into my NAD amplifier. Each source has a different (non-adjustable) output level. So when I switch each one at the Amp input selector the output volume changes significantly. I just want to attenuate the two highest outputs with a trimpot at source before inputting to the amp, so that each are roughly at the same level. Any idea what value trimpots I can use?

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barrykap
barrykap

5 years ago

Thanks. I think I will use a 'big' pot to test/set the level, then measure the resistance and fit fixed resistors on each channel. This way no need for separate 'balancing' adjustmnet of the trimpots.

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steveastrouk
steveastrouk

Answer 5 years ago

That's what I was about to suggest. You need to sort out the division ratio, then you can put what you want in.

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barrykap
barrykap

5 years ago

Only ones I have in my 'stock' is 200 ohms and 20K ohms. Would either of those do?

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steveastrouk
steveastrouk

Answer 5 years ago

The 20K for preference, 200 sounds too low to me.

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steveastrouk
steveastrouk

5 years ago

For audio, you'll need audio or log taper pots , do you know what the NAD input impedance is ? I'd try 10K log pots.

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barrykap
barrykap

Answer 5 years ago

Thanks

I have no idea what the impedance of input is. Lost the manual years ago. :-(

It's a C326BEE if anyone else knows.

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steveastrouk
steveastrouk

Answer 5 years ago

What I'd try to do is make the pots high enough they don't load the source too much and low enough that the input of the amp is higher than they are. Maybe a lower value than I suggested would be fine too.