Stereo to Mono connector wiring

Thread Starter

frenchie29

Joined Nov 28, 2008
134
I need to go from a stereo 3.5 male cable to a stereo 3.5 female connector The thing is the amp I am working on is mono. On the PCB I have Audio In and Ground. How do I wire the female connector to the PCB??

I know with XLR pin 1 & 3 are looped together is it the same for TRS????
 

Audioguru

Joined Dec 20, 2007
11,251
You do not know if the music source will blow up if you short the channels together. I would make a mixer with two series 3.3k resistors.
 

Thread Starter

frenchie29

Joined Nov 28, 2008
134
You do not know if the music source will blow up if you short the channels together. I would make a mixer with two series 3.3k resistors.
What do you mean by mixer? Basically it would be the same as one of those connectors that goes from stereo to mono.
 

Thread Starter

frenchie29

Joined Nov 28, 2008
134
That's what I did for now, I know I'm doubling the impedance but that's all I can think of.

connector---------------PCB

tip-------------------->Audio In
Ring------------------->Audio In
Sleeve----------------->Ground
 
Last edited:

Thread Starter

frenchie29

Joined Nov 28, 2008
134
Very nice, are the resistors necessary? I did it without resistors I taught it would double up the signal level but it didn't. Would jumping the L and R and put 1 10k do the same thing? Also did you make that schematic? The software I use doesn't have any audio symbols at all.

Thanks
 

Audioguru

Joined Dec 20, 2007
11,251
The resistors are the mixer. They mix the left channel with the right channel to avoid shorting the left channel to the right channel that might blow up something.

An XLR connector is a mono balanced signal, not stereo. By shorting one of the balanced wires to ground then the signal becomes unbalanced.
 

KL7AJ

Joined Nov 4, 2008
2,223
You do not know if the music source will blow up if you short the channels together. I would make a mixer with two series 3.3k resistors.

I agree the simplest and safest method is with just a pair of isolation resistors. (These aren't really in series, except from the point of view of the source ends...they're in parallel "looking" the other way. :)

eric
 

Thread Starter

frenchie29

Joined Nov 28, 2008
134
What about those stereo to mono connectors they sell at Radio Shack? I think they just mix the 2 signals together. I'll try the resistors tonight. Thanks guys
 
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