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Merge Two Stereo Signals Into One

DaveHoffman

Sep 27, 2014
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Greetings! I'm no electronics engineer, so I thought this would be a good place to get some advice. I'm doing some recording and need to merge the audio out from my computer to the audio out from my mixer.

I know that I can't just use a Y-connector for that and would instead need to add resistors to each of the lines from the computer and mixer. But I was wondering if there was an off the shelf solution.

Never mind. I'm going to use two headphone volume control cables and a Y-adapter.
 
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(*steve*)

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A headphone splitter in reverse would probably have too low an impedance.

I would place a resistor (between 1k and 10k) in series with the signal outputs, then join the ends of these resistors together and that will be your combined output.

mixer.png

Inputs on the left, output on the right. R1 and R2 should be the same value.
 

Gryd3

Jun 25, 2014
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Greetings! I'm no electronics engineer, so I thought this would be a good place to get some advice. I'm doing some recording and need to merge the audio out from my computer to the audio out from my mixer.

I know that I can't just use a Y-connector for that and would instead need to add resistors to each of the lines from the computer and mixer. But I was wondering if there was an off the shelf solution.

Never mind. I'm going to use two headphone volume control cables and a Y-adapter.
Can you not feed your computer audio out to an input on the mixer to handle this for you?
 

DaveHoffman

Sep 27, 2014
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A headphone splitter in reverse would probably have too low an impedance.

I would place a resistor (between 1k and 10k) in series with the signal outputs, then join the ends of these resistors together and that will be your combined output.

View attachment 15562

Inputs on the left, output on the right. R1 and R2 should be the same value.
Would a 10k resistor give less volume than a 1k?
 

(*steve*)

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Would a 10k resistor give less volume than a 1k?
It depends on the impedance of the signal source and that of the amplifier you're connecting it to.

the resistors should provide a load for the outputs that isn't too demanding (ie not too low) but also not higher than the input impedance of the amplifier you're driving. This I'd a pretty wide range in most cases.
 

Gryd3

Jun 25, 2014
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I'm recording and all the mixer inputs go to the main out of the mixer.
I understand your inputs go to the main out of the mixer, but the computer could be an input as well unless all of your inputs are currently taken
Using higher value resistors will 'slightly' decrease the final output volume.

Your original idea of a headphone splitter with independent volume control seems like it will work just fine and should allow you to easily and quickly adjust the level of each output. It's not ideal, but again, using the resistor method isn't either as you will need 4 resistors (1 per channel per device) and it MUST be shielded or you will pick up noise. I know this from experience as I made one for my audio input for my stereo.

Depending on the inputs you are using, you could also daisy chain your computer... sounds odd, but remove one of the input devices from the mixer, and run it to the audio in on the computer. Open you recording devices and make sure that 'listen to this device' is enabled, and your computer will play any sound it receives on that input.
You can then connect your computer to the now free input on the mixer and all sounds will be merged for you.
 

DaveHoffman

Sep 27, 2014
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I tried this with 10k Ohm resistors and could barely hear it, but it did work. I'll try it with less resistance and see if that fixes it.
 

(*steve*)

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That tells me that your amplifier has a low input impedance.
 
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