Stereo to Mono connector wiring

Discussion in 'The Projects Forum' started by frenchie29, Apr 27, 2009.

  1. frenchie29

    frenchie29 Thread Starter Active Member

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    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????
  2. Audioguru

    Audioguru New Member

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    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.
  3. frenchie29

    frenchie29 Thread Starter Active Member

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    What do you mean by mixer? Basically it would be the same as one of those connectors that goes from stereo to mono.
  4. frenchie29

    frenchie29 Thread Starter Active Member

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    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: Apr 27, 2009
  5. frenchie29

    frenchie29 Thread Starter Active Member

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    Last edited: Apr 27, 2009
  6. tkng211

    tkng211 Active Member

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    You may try this by adding a few parts. Then you can have the signals from both left and right channels feeding to the mono amplifier.

    Attached Files:

  7. frenchie29

    frenchie29 Thread Starter Active Member

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    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
  8. Audioguru

    Audioguru New Member

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    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.
  9. KL7AJ

    KL7AJ E-book Developer

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    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
  10. frenchie29

    frenchie29 Thread Starter Active Member

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    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
  11. SgtWookie

    SgtWookie Expert

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    Those are for people who don't know any better.

    You've been given great advice already. Follow it for good results.
  12. frenchie29

    frenchie29 Thread Starter Active Member

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    Would one 8k or 10k resistor do the same as 2 separate resistors?
    Last edited: Apr 28, 2009
  13. CDRIVE

    CDRIVE Senior Member

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    No, you need both of them for proper ballance. ;)
  14. frenchie29

    frenchie29 Thread Starter Active Member

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    Nice signature CDRIVE, I wish I had 1/100th of that experience.
  15. CDRIVE

    CDRIVE Senior Member

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    Unfortunately, it comes with a price. My GP, Gastroenterologist and Dentist are all in my speed dial. :D
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