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I have a mono line-level output and I want to share it with two devices which will receive the line level output and use it.

In one of those devices I need to use a 10 kΩ potentiometer in order to control the signal level that goes the device.

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Does this 10 kΩ potentiometer affect the signal on device 1? I mean, will the signal get lower or lose any bass?

I am asking this because, as I see the potentiometer that was added is in parallel between + and - I think it should affect device 1 a little bit.

I am not sure because I am confident that devices 1 and 2 have high input impedance, so maybe this 10 kΩ resistor would not have much effect (less than 1%).

What do you think?

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    \$\begingroup\$ It might affect things a little if the output impedance of the "line-level" source is 1 kohm or greater. It might affect the bass a bit more than mids or treble if the output capacitor of the source is quite puny in value. \$\endgroup\$ Commented Feb 7, 2023 at 13:58
  • \$\begingroup\$ @Andyaka I dont have information about the source impedance... but to prevent problems (noise, underisable effects...) should I use a potentiometer with a higher value or lower? I am now using a 10K pot... should I use a bigger or smaller one in order to avoid problems? \$\endgroup\$ Commented Feb 7, 2023 at 16:00

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Will it affect it? Yes. Anytime you add an impedance in parallel there's going to be some effect.

Will the effect be noticeable? Maybe, maybe not. Without knowing the impedances of devices 1 & 2 and the output impedance of whatever is driving them it's impossible to say.

In general, the higher the impedances of 1 & 2 and the lower the impedance of the driving circuit, the less of an effect the pot will have.

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  • \$\begingroup\$ The devices 1 and 2 are gonna be an amplifier which will driver speakers. If I dont have any more information about the amplifider would you mind telling me this: to prevent problems (noise, underisable effects...) should I use a potentiometer with a higher value or lower? I am now using a 10K pot... should I use a bigger or smaller one in order to avoid problems? \$\endgroup\$ Commented Feb 7, 2023 at 15:59
  • \$\begingroup\$ @amandanovaes You're probably fine with 10k. Line level output is usually 100 to 600 ohms, line input is usually 10k. If we use those values, with the pot at full volume you'd have worst case a 600 ohm source into 5000 ohm load, using the voltage divider formula that gives you around 89% of the original signal. With a 600 ohm source into 10k load (line input without the pot) it would be around 94%, so not a big difference. \$\endgroup\$ Commented Feb 7, 2023 at 16:35

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