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Why does the sound out of my speakers come out so badly when I connect two audio sources to one output? Answered


I've bought two stereo male TRS plugs and one female TRS plug along with some audio cable.

I hooked up the one male plug to the audio cable and then did the same with the other male cable.

I then joined the cables at the other end to form one cable so that I could solder this to the female plug.

I then plugged it all in but the output sound is very low and I was hoping someone might be able to tell me why this is? I have earthed it, which removed the humming sound but the output sound is still very low despite turning all the volume options up on my speakers and two pc's.

Ideally, if this works, I can use Android VNC to log into either machine and control the volume this way (I have not found an app yet to remotely control just the sound which would be ideal) or just leave my music player running on the "server" which I then control from something like WinAmp remote.

If someone could tell me why I am getting such low output volumes, I would appreciate it :)



Does the volume recover, if you only use one input ? There is a fair chance you have damaged your audio outputs, because they are NOT designed to be connected together.

Hi Steve,

I've removed the plugs now and both are working fine as single outputs so nothing seems damaged. Phew! I was not aware that I could damage them?

This is basically what I want to put together.


Many thanks,

NOT a good idea.

If you want to do it, you really need to make a little mixer box.

Thanks guys, I am assuming there are mixer boxes for sale like this?

Thanks again for all your input.

Here's a really simple circuit. You can ditch the pots on the inputs, but you need everything else.


Thanks Steve, I wouldn't know what to do with this though being a complete beginner. I am however looking at some of the other examples on the site. Maybe as I learn more, I will grasp this one. Thanks though ;)

Ok, I will give it a try. Is there a cheat sheet of sorts to understand all the diagram symbols maybe?

Thanks :)

The squiggly things are resistors. The separated plates are capacitors. The triangle is a thing called an op-amp. The opamp's pin are numbered, though the numbers aren't written on the packages. There is a marker on the top edge of the package that tells you which way to look at it.

So the pins, looked at from the top side witth the writing on, are numbered

1 V 8
2 7
3 6
4 5

The marker is the "V"

Make all the resistors 10K, rather than the 100K I suggested there.


steve is right; it's probably low output to the speaker because the other output will be sucking up the power before it can hit the speaker.

The circuit you want is a mixer (probably need to wire an ic) or just pick up a mixer designed for the job.