I am connecting a stereo signal and a mono signal to the same stereo output.
So the issue is... the stereo signal runs down the wire, then up the mono wire combining the left and right channels turning my stereo signal into mono.
I want the mono to play mono sound to the output and the stereo to play stereo sound to the output... how do I do this?
I thought maybe using diodes, but that might lower the volume/quality?
Note: I will not be using the mono and stereo input at the same time.

 

You need a mixer. There are passive ways to do this and methods that use small amplifiers.
Google, "audio mixers" and come back when you have an idea about which style you want.
If you can get specific about what signal levels you have to work with we can sort something out for you.

 

You need a mixer. There are passive ways to do this and methods that use small amplifiers.
Google, "audio mixers" and come back when you have an idea about which style you want.
If you can get specific about what signal levels you have to work with we can sort something out for you.

Sorry. I just edited my post to add an image. No additional amplification. Just standard audio input. Eg. Music straight from a phone.

 

I would prefer no amplification of the audio signal. I just want to stop it crossing the wires.

 

This depends very much on how the sources of your audio are built. Small amplifiers might have resistors built in to keep them from getting shorted out. If it works, fine. You're done. If the signals fight each other you will have to add resistors to keep them apart. If the grounds fight, you have bigger problems, but a phone wouldn't cause that problem, so you're probably O.K. on the ground side.

Oh...I get it. The stereo signal falls apart because it is shorted by the mono wires.
This calls for resistors.

Examine this:http://sound.westhost.com/articles/audio-mixing.htm

 

This depends very much on how the sources of your audio are built. Small amplifiers might have resistors built in to keep them from getting shorted out. If it works, fine. You're done. If the signals fight each other you will have to add resistors to keep them apart. If the grounds fight, you have bigger problems, but a phone wouldn't cause that problem, so you're probably O.K. on the ground side.

Oh...I get it. The stereo signal falls apart because it is shorted by the mono wires.
This calls for resistors.

Examine this:http://sound.westhost.com/articles/audio-mixing.htm

Spot on. My stereo wires are being joined together by the mono effectively making my stereo "mono".
Where would the resisters be required in my wiring?

 

One resistor in series with each audio wire. Just short all the grounds together.

 

I'll give it a go. Thank you.