What is the name of the circuit that takes an audio input and outputs two?

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Hi everyone (newbie first post),

I want to make a simple preamp circuit that takes L and R channels and outputs 2 of each. In my newbie brain, that's 2ch audio to 4ch audio. I imagine this should be simple, and I guess I could just use a splitter wire (but wouldn't that reduce my volume?). I have no idea what this kind of circuit is, so I am having trouble finding one. If someone could give me the name, I am sure I can find a reference circuit from TI or elsewhere.

Thanks for your help.
 
A “Y” splitter will probably work, if you’re driving with a fairly low impedance source into two fairly high impedance inputs. However, if you’re driving it with a 50K volume control, you may have problems. I would certainly try the splitter first. No sense solving problems you may not have.

That said, if you do need to do it electronically, the circuit you’re looking for is a buffer.

Regards,
Mike
 
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Joined 2012
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If you have enough drive from your source, and the loads (amp inputs) are high impedance, a Y splitter with a pair of 220ohm to 2k ohm resistors may work just fine. Try it. If you need to drive two rather difficult loads, then add a unity gain buffer opamp after each resistor. It’s also called a “fan out” or distribution amplifier.

Maybe something like this (the first opamp may not even be necessary):
An externally hosted image should be here but it was not working when we last tested it.
 
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This is the main question:
Hi everyone (newbie first post),

I want to make a simple preamp circuit that takes L and R channels and outputs 2 of each. In my newbie brain, that's 2ch audio to 4ch audio.
And the answer is :
No.
No way.
Nothing like that happens.
You still have 2 channels.

After that, any discussion about splitters,impedance, etc. is irrelevant; technically interesting but not addressing the main question.
 
Hi everyone (newbie first post),

I want to make a simple preamp circuit that takes L and R channels and outputs 2 of each. In my newbie brain, that's 2ch audio to 4ch audio. I imagine this should be simple, and I guess I could just use a splitter wire (but wouldn't that reduce my volume?). I have no idea what this kind of circuit is, so I am having trouble finding one. If someone could give me the name, I am sure I can find a reference circuit from TI or elsewhere.

Thanks for your help.


You won't get "4ch audio" that way...it's still going to be 2 channels with two outputs for each channel, so it will still be two channel stereo.

Mike
 
Member
Joined 2008
Paid Member
I think the confusion here is whether Alialiali understands what he is asking for and what others are offering a solution to. If you are referring to “channels” in the sense that you simply want the same two signals split off to run to a secondary amp and speakers you are interested in experimenting with or provide sound elsewhere (perhaps another room?) then a “Y” splitter or one of the other buffer splitter solutions will probably work.

However, if you are expecting to split a stereo signal and gain additional channels of sound to create a surround sound/home theater system or quadrophonic sound these “splitter” solutions will not get you there. You will simply have additional connections that carry the same exact stereo signal and you may have issues driving additional amps and speakers by just splitting your signal with these methods depending on your sources ability to “drive” additional amps/speakers which in and of themselves have different “load” characteristics that they put on your source.

Adding a subwoofer or any additional speakers that you would want to generate different ranges of the sound frequency aoectrum would require some kind of dividing network or crossover in order to limit the frequency range presented to those individual speakers. Often a subwoofer will have its own dividing network/crossover built in along with its own amplifier. You need to confirm that fact and understand how to set its parameters.
 
He did say..."that's 2ch audio to 4ch audio", hence the need for clarification.

Mike

Yes, I was confused with the naming, but I don't expect to be inventing channels. Later when I add a sub woofer, I know I will need some kind of filter for that. But for now, just cloning the channels.

This is my first audio project, and my circuit boards are being printed for the amp. I have no idea if it will work, but here is what they look like:

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I already noticed one mistake with the standby not being connected to anything pin, but I think I can fix it to test at least.
 
With the Y-splitter solution you might get excessive distortion when one of the amplifiers is playing while the other one is off, particularly when the switched-off amplifier's volume potmeters are set to a very high level. Disconnecting the inputs of the switched-off amplifier or turning its volume pots fully anti-clockwise or switching it on will solve that.

The inputs of switched-off audio equipment may draw distorted input signal currents when you apply input signal voltages.
 
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