MacBook Pro Core Audio problem

Discussion in 'Audio Hardware' started by EdogawaRampo, Aug 13, 2017.

  1. EdogawaRampo

    EdogawaRampo Forum Resident Thread Starter

    I use my late 2011 MacBook pro to play music files but a funny problem has popped up -- it outputs everything in mono. It still records in stereo all right, just outputs mono when it comes time to play. I tried the quick fixes of resetting PRAM, going to the terminal to kill coreaudio then restart, but neither did any good. I swapped in my work MacBook pro and that one is fine with stereo.

    If anyone has any suggestions I'm all ears.

    It's an early 2011 MacBook pro running OSX El Capitan v. 10.11.6
     
  2. Steve Martin

    Steve Martin Forum Resident

    Location:
    Plano, TX
    There is an application in your Utilities folder called Audio Midi Setup. Open that, and with the "built in output" selected. Click "Configure Speakers". Is that set to stereo?
     
  3. EdogawaRampo

    EdogawaRampo Forum Resident Thread Starter

    Yes.
     
  4. Gaslight

    Gaslight Cave dwelller

    Location:
    Northeast USA
    Suggest eliminating the hardware as a problem. Easiest way to do that is to create a bootable Linux USB drive, with a few tunes on there and then once it fires up, try it out.

    If the output is mono, then it's likely hardware ie. your headphone out jack is to blame. If it's in stereo then at least you know it's something software based.
     
  5. Jack Flannery

    Jack Flannery Forum Resident

    Location:
    Houston, TX
    What software you running? Using the headphone jack or do you have an external dac/amp? Two channel mono or just one channel working?

    Output stereo as mono in OS X
     
  6. EdogawaRampo

    EdogawaRampo Forum Resident Thread Starter

    I have an external DAC out a USB port. Output is two channel mono -- but this is curious. When I 'configure speakers' in AudioMIDI, I can get the speakers in my stereo system to play the test sound left and right, but when I go to play a file it switches back to the laptop speakers even when I have system prefs, AudioMidi and the software itself all set to output to the DAC. Really frustrating. I wonder what's going on. My work laptop plays everything fine, works as it should, so it's just the old Mac that's having the problems.
     
  7. Grawlix

    Grawlix Member

    Location:
    California
    Under the Audio tab in Accessibility in the System Preferences, there's a checkbox labeled "Play stereo audio as mono" Is that checked?
     
  8. Steve Martin

    Steve Martin Forum Resident

    Location:
    Plano, TX
    Have you said yet what software you are using to play the audio? I don't see it.
     
  9. EdogawaRampo

    EdogawaRampo Forum Resident Thread Starter

    I use Amadeus Pro and VLC.
     
  10. EdogawaRampo

    EdogawaRampo Forum Resident Thread Starter

    Yes! Many thanks...that could be it. Damn...I believe that may have been a problem some time back as well, but I forgot all about it. I certainly did not check it myself as I never go in there, but for some reason it switches / glitches itself from time to time.
     
  11. EdogawaRampo

    EdogawaRampo Forum Resident Thread Starter

    Well, I'm not there yet...I can get stereo to work on the laptop speakers now, but for some reason I can't output through any of the usb ports to my outboard dac, despite system prefs, AudioMidi setup and the software prefs all recognising the DAC. I've rebooted a dozen times, unplugged and replugged, turned everything on and off and no success yet...sheesh.
     
  12. Synthfreek

    Synthfreek Please label the photos you post

    Location:
    Austin, TX
    You haven't forgotten to actually click your dac on the audio/midi devices screen and choose play audio using this device (or whatever it says) from the drop-down menu have you?
     
  13. EdogawaRampo

    EdogawaRampo Forum Resident Thread Starter

    No, haven't forgotten. Checked it dozens of times. Something's just not connecting somewhere, despite all the drop downs correctly checked.
     
  14. Rolltide

    Rolltide Forum Resident

    Location:
    Vallejo, CA
    Might as well reset the PRAM. It occasionally fixes odd problems like this.
     
  15. EdogawaRampo

    EdogawaRampo Forum Resident Thread Starter

    Already did that a couple of times.
     
  16. Jack Flannery

    Jack Flannery Forum Resident

    Location:
    Houston, TX
    Have you given iTunes a shot?
     
  17. Rolltide

    Rolltide Forum Resident

    Location:
    Vallejo, CA
    Then the only other possible troubleshooting step I can think of (beyond wipe/reinstall) is reinstalling the latest osx combo update, which will overwrite some core system files.
     
  18. EdogawaRampo

    EdogawaRampo Forum Resident Thread Starter

    Now it works. :confused:

    Dozens of reboots later, at least a half dozen PRAM resets...and every setting checked and rechecked correct each time, resulting in nothing, and now -- with none of the settings any different -- it works.

    Bug in the works for sure. On two of the PRAM resets I saw the crazy color banding on the gray screen that says somethings buggy or failing in there...I'm keeping my fingers crossed.
     

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