Electrical – Mixing analog audio signals with resistors

audiomixerresistanceresistors

I am creating a type of mixer for 2 audio inputs into 1 output so i can use 1 pair of headphones with 2 computers without buying an expensive mixer with a amp

Currently i have 1k 1/2W metal resistors on both left and right input signals and nothing on ground

It works great and i can hear both inputs fine though the headphones but it really needs a amp and isnt usable

My question is: What resistors should i be using so there isnt so much volume loss?

Best Answer

I think you'll need more than just resistors to do what you are describing properly. You should probably go active. You could try a simple summing amplifier like this:

Op amp summing mixer

This will invert your signal but you can always add another simple inverting amplifier stage at its output (basically the same thing in this schematic except only using 1 resistor at its input).

You will have less loss this way and you can even apply gain if you want to (determined by Rf/Rin). If you add a potentiometer for each input, you'd have individual volume control for each one. You can add more inputs if you like as well.

Hope this helps!

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