Small patch cord build project - Just one question.

Discussion in 'The Projects Forum' started by kytrid, Mar 21, 2016.

  1. kytrid

    Thread Starter New Member

    Mar 21, 2016
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    0
    My electronics level is: a little knowledge is a dangerous thing.

    I want to construct a patch cord for a specific application - I've got a little cheapo chinese S.M.S.L. amp that I picked up on ebay for a project a year or so ago (long enough that the amp I bought is no longer available), that I want to re-purpose. It's more or less like http://www.ebay.com/itm/SMSL-SA36A-...P-12V-Power-/171915274685?hash=item2806f2e9bd.

    I'd like to use it as a headphone amp now. Unfortunately it doesn't have a headphone out of any sort, just 4 stereo outs, banana clip (red/black R, red/black L) on back. I'd like to build a patch cord that will bridge between those outs and a headphone jack. I've looked at some circuit diagrams online, and it seems that normal headphone jacks share their common ground, with a positive going to each side.

    Finally, the question: how do I wire a patch cord for this application? Can I just tie my two negative (black) wires to the common ground on the jack, and the L/R positives to their respective points? I think that will work, but I'd like input from someone that knows better than me.

    If you need more info, let me know

    Thanks, guys!
     
  2. blocco a spirale

    AAC Fanatic!

    Jun 18, 2008
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    You cannot joint the two "negative" outputs of this amplifier together because they are not at the same potential.

    [​IMG]
     
  3. kytrid

    Thread Starter New Member

    Mar 21, 2016
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    Thanks for the reply. I wish I knew enough electronics to read the schematic-- unfortunately I don't. I understand your statement to mean that my proposed solution isn't a solution at all, that a simple patch cord can't be built that will tie the speaker outs together into one jack. Is this correct?
     
  4. blocco a spirale

    AAC Fanatic!

    Jun 18, 2008
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    That's correct, unless you cut the plug off the headphones and split the common connections you can't use this amplifier but it wouldn't be a very good choice for a headphone amplifier so it's not really worth the effort.
     
  5. kytrid

    Thread Starter New Member

    Mar 21, 2016
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    Ah, I see. Thanks again for the quick responses. You've answered my question so that even I can understand. Much appreciated.
     
  6. Sensacell

    Well-Known Member

    Jun 19, 2012
    1,132
    267
    You could make it work with 1:1 audio transformers, these would let you tie the output grounds together on the isolated secondary side.

    - Again, probably not worth the trouble.
     
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