27" Dual Core NO GOOD FOR AUDIO RECORDING

Discussion in 'iMac' started by BruisedKnuckles, Apr 14, 2010.

  1. BruisedKnuckles macrumors newbie

    Joined:
    Apr 14, 2010
    #1
    i purchased a 27" imac dual core 3.06 when they were release about 7-8 months ago, since that day i have been battling issues with using recording software. Both Pro Tools and Logic, i get a whiney hum through my studio monitors both in record or playback, if i cease all audio after a couple of seconds, the hum goes away. Im guessing this is the audio engine enabling/disabling.

    I also have an issue where the machine will not send or recieve files over iChat.. the settings i have made are the same on both imac and MBP but MBP works fine


    Considering these machines are supposed to be used in the creative media industries dont you think i should be able to record in with no problems?

    Is this grounds enough to demand a replacement through Apple?
     
  2. Sir Cecil macrumors 6502a

    Joined:
    Mar 31, 2008
    #2
    What have you done to find the cause of the noise? Could be any number of things unrelated to the performance of the iMac. What sound card are you using? What speakers and how are they connected? What power and signal cabling? What relative positioning?

    Seems odd to post a definitive and damning statement about the iMac in your headline when you apparently have no idea what is causing the problem.
     
  3. BruisedKnuckles thread starter macrumors newbie

    Joined:
    Apr 14, 2010
    #3
    MBox Mini 2 connected via USB
    Connected to 2 KRK Rokit 6" via high quality sheilded 1/4" cables
    monitors positioned a meter each side of the monitor
    noise happens on both input and output
    noise does not happen on my MBP
    i have been told by a few audio engineers that something inside the casing could be touching something else

    i even get noise when i scroll or move the mouse. Normally indicating that it is an internal problem with the iMac itself.

    these are the reasons why i have posted such a definative statement, but there was supposed to be a question mark :p
     
  4. plasticphyte macrumors 6502

    Joined:
    Nov 9, 2009
    #4
    The latest EFI and other updates may not help, but if you haven't got them already, try them.

    Otherwise as you've already deduced, it is probably a problem with the iMac itself. If possible, try another iMac of the same type. Take yours to Apple to get it checked.
     
  5. myca macrumors 6502

    Joined:
    Oct 7, 2005
    #5
    I used to have a similar issue with my Pod XT on my PowerMac, whenever it was plugged in via USB there would be a buzz across my entire audio chain, but it works fine on my notebook and hackintosh with no noise. Likewise my MOTU 828 MKIII works fine on my PowerMac, my only guess was that there was a ground issue with the USB on my PowerMac.

    You may have a similar issue, if so I'd take it in to be looked at, as you are still under Applecare, and if as you say the issue isn't present on your MBP with the exact same set up the problem has to lie in your iMac.

    Of note at my workplace we have a few editing iMacs that use Mboxes, and apart from Digidesigns dubious Core Audio drivers they work perfectly, so iMac + Mbox should work fine.
     
  6. locomotivation macrumors newbie

    Joined:
    Aug 31, 2010
    #6
    Better late than never...

    I know this thread is old, but maybe this post will help someone else with the same issue.

    There's a simple solution to this kind of noise.
    I've had the same problem with computers from different manufacturers, and wasted loads of time and money trying to track it down. It's fairly common, and it turns out there's a very simple solution.

    It's usually caused by the ground connection on your AC plug. Go to a hardware store and get one of those orange 3-to-2 prong adapters for use with very old 2-prong AC outlets, but don't connect the green (ground) wire. Drop the ground and you will drop the noise. Works for me every time. Don't know if this may pose other undesirable side effects or risks, but it does get rid of this kind of noise. It's never caused me any trouble.

    cheers.
     
  7. Fishrrman macrumors G3

    Joined:
    Feb 20, 2009
    #7
    "It's usually caused by the ground connection on your AC plug. Go to a hardware store and get one of those orange 3-to-2 prong adapters for use with very old 2-prong AC outlets, but don't connect the green (ground) wire. Drop the ground and you will drop the noise. Works for me every time. Don't know if this may pose other undesirable side effects or risks, but it does get rid of this kind of noise. It's never caused me any trouble."

    Another thought:
    Could his wiring be "wrong" (that is, not properly configured on the "hot", "neutral", and "ground" sides of the circuit)?

    He might also pick up one of those cheap "circuit testers" from any home/building supply place, and check the outlet the Mac is plugged into.

    I live in a house built before 3-wire "grounded" circuits, with only "2-prongs" on each plug. I was worried about running the stuff in my computer room "non-grounded", and bought a C-clamp and some heavy-gauge copper wire, put in new 3-prong outlets, and ran a makeshift ground along the baseboards to the clamp on an old cast-iron radiator. Seems to work fine for me.
     

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