1/8" to 1/4" cord problems

Discussion in 'Digital Audio' started by recordme, Jun 17, 2008.

  1. recordme macrumors newbie

    Jun 17, 2008
    I am trying to run the headphone out of my Intel iMac to a mixer (Behringer UB802) via a 1/8" to 1/4" cord. Then to an external set of studio monitors (Alesis M1 Active). The problem is there is no sound when I do this. When I plug headphones into the headphone there is, of course, sound coming out of the headphones. Does anyone know what my problem might be? I did notice that the plug-in for the headphones has 3 different "sections", and the plug-in for the cord I am using has two different "sections". Thanks for any help.:apple:
  2. BigPrince macrumors 68020

    Dec 27, 2006
    Apple-->System Preferences-->Sound-->Output tab and check to see if the right output is selected.

    Also, the cable might need to be a Mono to Mono.

    What you describe is a Stereo to Mono.

    I think.

    I know in my experience either one works, but on occasion I struggle with the mono to stero.
  3. cschreppel macrumors regular

    Jul 17, 2006
    Boston, MA
    1/8" headphone cords are TRS (tip - ring - sleeve) which can transmit stereo material. It sounds like you're using a TS (tip - sleeve) cable.

    Chances are, you'll need an 1/8" stereo - to - 1/4" dual mono Y-cable. You can find this at Radio Shack or some place similar. Most mixers don't have stereo inputs (even though they may have stereo channels), so you need to run your computer's output dual-mono into your mixer.
  4. Xander562 macrumors 68000


    Apr 2, 2006
    Even if it was a stereo to mono, the left speaker would work. But he gets no sound.

    They are right, however, that you need to make sure you are getting a stereo to stereo conversion. An easy way to tell is by counting the number of plastic rings the connectors had. 1=mono 2=stereo. However even if you have a stereo cable, it needs to be a stereo input. If not, just use a Y-cable as cschreppel recommends and put them into separate channels on the mixer. (Just remember to turn the balance on the left input to the left and the right input to the right, to maintain stereo-ness)
  5. AviationFan macrumors 6502a


    Jan 12, 2006
    Cedar Rapids, IA
    That's right, and it takes care of two problems:
    1. Splitting the stereo into two monos, since all the UB802's input connectors are mono. The stereo channels of this mixers simply use two connectors each, one for left and one for right.
    2. The mixer inputs are balanced. You should be able to get sound out of them by feeding an unbalanced signal using a TS (tip - sleeve) connector, but passing a stereo signal on a TRS plug could, in theory, lead to no sound due to cancellation of the two signals. The mixer would consider a perfectly centered signal (i.e., same signal on left and right) as noise and remove it completely.
    The other problem is that the headphone output is a little hot for a line level signal, because it's already been amplified to drive the headphones. Using a very low volume on the iMac and lots of attenuation in the mixer may lead to useable results.

    recordme, I'd get a cheap Y-adapter like cschreppel suggested (such as this one) and give that a try. If that doesn't give you good enough quality, a (big) step up would be an etxernal audio interface for your iMac with balanced line outs.

    - Martin

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