iMac i7 Audio Issue

Discussion in 'iMac' started by edramatica, Nov 24, 2009.

  1. edramatica macrumors newbie

    Nov 12, 2009
    Mine just arrived yesterday afternoon and after goofing around with it for a bit at the office, I finally got it home in the evening only to discover a glaring audio problem.

    When I hook up speakers to the headphone jack in the back, anytime audio plays there's a very distinct and hissing sound that sounds like white noise. For example, if I just hit the volume up or volume down button to make that beep sound whenever you adjust the volume the hiss comes on for about 15 seconds and goes away. If I play music, it's there the entire time until the song ends and it shuts off about 15 seconds after the song ends.

    There's no issue if I use the internal speakers and I don't notice a hiss when using regular earphones or a pair of headphones. If I plug in the speakers though the hiss comes through when audio is playing. There's definitely nothing wrong with the speakers because they function perfectly on a Mac Pro Octo sitting right next to it.

    I also tried wiping the OS and doing everything from scratch and it's the same issue.
  2. blusk06 macrumors newbie

    Nov 6, 2009
    i had an audio issue with Bose Companion 5 USB speakers in Command and Conquer 3 and it was resolved by just using the internal speakers. i would suggest to call apple. however you could try to reset your pram (option+command+p+r at boot until you hear 2nd chime)
  3. upwest macrumors newbie

    Dec 4, 2009
    iMac i7 Audio Issue


    I was actually hoping I wouldn't find someone else with this problem! Sadly, I too just received my i7 iMac today and am experiencing the exact same symptoms of audio hissing, but only when I plug in speakers. I too have tested my own speakers with a different MacBook so those are not the problem. The built in speakers seem to work fine so I'm hopeful that it's not a sound card issue... does anyone know if this type of issue can be resolved with a software update? Or is it likely to result in having to return the iMac to get a new one?
  4. fab672000 macrumors newbie

    Dec 14, 2009
    Not sure, but this audio issue looks like a ground plug problem on these macs.
    With some luck, plugin the imac to an outlet that has a good grounded pin would help. With no luck, it could also be that the ground wire of the audio output is not soldered correctly ?
    Looks like these new imacs have more than a problem for many people, I read that some had a broken screen at delivery time :(
  5. slicecom macrumors 68020

    Aug 29, 2003
    Toronto, Canada
    For those of you having audio issues with USB speakers, try plugging them in through a powered USB hub. This solved my high pitched beeping / interference noise in my studio monitors. I think the USB power output level is very low on the iMacs which seems to cause some problems.
  6. efpw macrumors newbie

    Dec 15, 2009
    Me Too

    I'm having exactly the same problem as described by 'edramatica' and 'upwest'. Has anyone solved this problem? It's going to drive me crazy and renders it useless as a music centre..
  7. wwwlsnr30 macrumors newbie

    Dec 19, 2009
    I'm having the same problem.

    I also note that the audio output seems a lot lighter than on previous iMacs .. I have to crank the volume up to 11 a la Spinal Tap.

    Any help would be much appreciated ...

    Apple II
    Apple Lisa
    Apple Mac
    Apple Mac SE
    Apple Mac Performa 550
    Apple Quadra 68040
    Apple iMac
    Apple iMac G5 20"
    Apple iMac 24" Core Duo
    Apple iMac 27" i7
    iPhone 3G

    ... and lots and lots of other kit :)
  8. efpw macrumors newbie

    Dec 15, 2009
    Problem Solved

    I called in to Applecare about this problem and their instructions, which solved the problem, were as follows:

    1. Zap the PRAM (Reset the PRAM). This is achieved by shutting the computer down. Locate the Cmd, Alt, 'P' and 'R' keys and restart the computer with all four of these keys pressed. Keep the keys pressed until you hear the log-in 'Chime' twice.

    2. When the login screen comes up click on the Shut Down button at the bottom of the window without logging in to any of the accounts.

    3. Once shut down. Unplug all cables, including the power cord, and wait for 15-30 seconds.

    4. Re-connect the power cord and re-start your computer.

    Bingo! Problem solved.

    I hope this helps.
  9. efpw macrumors newbie

    Dec 15, 2009
    Oh dear

    I spoke too soon. For a short while the problem was solved and the sound quality was spot on. Now the hiss is back and more irritating than ever, having experienced some time without it.

    This is weird, because it must mean that the system is setting some parameter, which had been cleared by zapping the PRAM!

    Applecare forwarded the following link to me, but this does not explain the problem fully, nor provide a satisfactory solution in my opinion:

    Any views on this out there?

  10. Bitwise macrumors member

    Jan 1, 2010
    Portland, OR
    Yup the new iMacs have weird radio frequency issues. I have a firewire audio interface with two studio monitors, and I experience really loud buzzing and frequencies when moving the mouse, clicking, or pretty much doing anything else with the computer. Some computers are more prone to these issues, and the new iMac just happens to be one of them. I completely removed the noise by using some three to two prong adaptors with my studio monitors. I also tested this with the iMac. When plugging the iMac in using a three to two prong adaptor the noise is also removed (I would not recommend doing this with the iMac).

    Here is something that slicecom recommended to me in another thread.

    Since the three to two prong adaptor removes all noise when used with the iMac or external speakers, then this should work without putting your computer or speakers at risk.
  11. efpw macrumors newbie

    Dec 15, 2009

    Thx Bitwise for the advice. I am based in the UK, so will have to find an equivalent, but very grateful for the advice.
  12. efpw macrumors newbie

    Dec 15, 2009
    Still working on it

    I have to say that I am unimpressed with Apple shipping an iMac with such audio issues when iTunes is central to so much of their marketing hype..

    My latest work-around is the Griffin 'noise-reducing audio cable', which (and I hope that I am not speaking too soon) appears to be working. You lose a great deal of amplitude, but it appears to do the trick for $20.
    This can be found here`:
    and I include a picture, attached.
    The boring thing about this bit of kit is that it is male-to-male, so you need a 3.5mm female-to-female adaptor.

    The alternative for audiophiles with deeper wallets, and untested by me, is the 'ISO MAX' noise isolator from Jensen Transformers, model CI-2MINI. It is not listed on their website ( ), but has a similar spec. to the CI-2RR. The price is a whopping $177.95, so it had better be good. The indication is that it will be, as Jensen are often on the circuit speaking as the audio industry experts at isolating ground loops. Picture attached.

    I hope this helps..

    Attached Files:

  13. knewsom macrumors 6502a

    Jun 9, 2005
    When I'm not using the internal speakers, I use the digital audio out to my surround sound receiver, and have had zero trouble. EXCELLENT sound quality. Has anyone with this problem witnessed it when using the TOSLINK audio output?
  14. grinch51 macrumors newbie

    Feb 9, 2010
    iMac external speaker hiss solution - USB sound card

    Got the 27-inch, i7, 8 gig iMac two weeks ago and love it, no screen problems, thank you very much.

    Alas, I have the same problem as the original poster -- my external speaker hiss continues for 30 seconds, until the internal sound card "goes to sleep." The simplest work around is to get a USB external sound card. (I got the Turtle Beach Audio Advantage Micro, which also has an optical output, for $30 at Amazon, although you could also buy the venerable iMic for the same amount and be able to rip vinyl and tape.)

    Over the phone, an Apple tech said the problem may be with the internal sound card cable, and since I'm still under warranty, I may lug my computer in to have it looked at, just to make sure it's not a symptom of a more serious problem. But I'll probably stick with the USB external sound card because it provides excellent sound. And yes, the volume can still be controlled by the Apple remote.
  15. goldenpiggy macrumors newbie

    Jan 29, 2010
    Gurnee, IL
    I use this nifty USB DAC to eliminate any hum, buzz, and poor audio. It also has headphone output:

    (They have distributors all over the world.)

    Actually just about any outboard DAC that accepts the common Toslink optical will work. The iMac's 1/8" headphone/line-out jack does double duty as optical output, although you need an adapter to convert the standard Toslink connector into a 1/8" headphone form factor. The optical connection breaks the electrical ground path, so bye bye hum, buzz,...

    Finally most audio interface used for hard disk recording (firewire or USB) would do. You can find some really good deals on used MOTU interfaces.
  16. owen9955 macrumors newbie

    Mar 19, 2010
    27" i7 Imac Audio Hiss.

    I was having a problem too with loud hissing coming from my Mako Razer 2.1 connected using the inputs at the back of the subwoofer. even with high quality connection leads ( Mini jack & phono), it was constant whenever "any" audio was being played.
    This never happened with any of my previous Imacs, Macbooks or ipods.
    I even went as far as contacting Apple customer service, who asked me to download a program which tested the imacs hardware and sent them a report. All to no avail because the imac was in perfect working order.Hence no fix or hardware patch.
    In my case the solution was a simple one, if you are using external speakers which have a headphone (mini jack) input located on the volume control , try using that instead, ( mini jack to mini jack lead, best quality you can get ).Or sending the signal through a separate audio device, like a tape deck - (what's that ?... I hear the young cry ) - or an external amplifier also works, but is a chore to set up.
    It worked for me.
    Hopes this helps.
  17. Xiao macrumors newbie

    Nov 12, 2009
    Bump, Bump

    No solution? I'm having this problem too
  18. dwarnecke11 macrumors 6502

    Nov 29, 2009
    Same - and my audio hardware makes a quiet "pop" when it wakes up or goes to sleep.
  19. Xiao macrumors newbie

    Nov 12, 2009
    Wonder if apple can give me a replacement xDDD
  20. hashilli macrumors member

    Feb 13, 2007
    The surround sound receiver is taking care of any line noise for you. I did not have any line noise to a receiver. Plugged the same iMac directly into some Mackie MR8 powered studio monitors from the 1/8" to RCA cables, and nasty nasty line noise when the Mackies are turned half way up.
  21. hashilli macrumors member

    Feb 13, 2007
    I'm glad your sound card worked for you. However, I got a USB DAC (Nuforce uDAC-2 $129) that I thought would solve my problems too. Nope, the line noise still is present for me. I still can't use my Mackie MR8 powered studio monitors more than half volume (set on the mackies) because the line noise is too horrible.

    USB has the same ground loop noise issue that is coming out of my 1/8" out on my iMac. This has nothing to do with anything else in the setup. disconnect from the iMac, no noise. I plug into anything else, no noise. 1/8" direct from a dell lappy, no noise. Lappy USB to DAC to monitors, no noise.

    The source is the iMac. I have seen several places where someone suggests to remove the ground plug from the three prong iMac power cord. I think this is a really bad idea. Ground is there to protect the equipment and you. This is especially bad when you are plugging in other externally powered devices into the iMac.

    No ground plug is not a solution. A line noise filter on a 1/8" cable is not a 'solution'.
  22. hashilli macrumors member

    Feb 13, 2007

    As you can see from my post above, a simple USB DAC did not solve my problems. The Nuforce uDAC-2 is still picking up noise from the USB connection. I had the iMac hooked up to a AVR past the first 30 days I had the machine and did not hear the noise till after my return window was up. Not happy at all.
  23. slicecom macrumors 68020

    Aug 29, 2003
    Toronto, Canada
    This is the only acceptable solution I've come up with. It's worked for me for over a year now.
  24. hashilli macrumors member

    Feb 13, 2007
    Interesting. I should have added that I have the iMac plugged into an Opti UPS which is then chained to an Tripplite ISOBAR8ULTRA. The iMac is the only thing plugged into the UPS. I have not yet tried to plug the iMac directly into the ISOBAR. I shouldn't have to as the isobar has isolated filter banks which, as far as I understand, essentially perform the same task as the Hum-X (Hum Exterminator) plug that you linked to.

    From Unique isolated filter bank design offers additional filtering between each duplex pair of outlets on the strip to prevent electrical noise interference between connected loads.

    I had planned on checking out a direct connection to the isobar after work today. I'll also confirm that I am using one of the isolated filter outlets. I can also try a second Tripplite product. I bought both of these surge protectors specifically for their durable metal exteriors, high rated specifications and many reports that they cleaned up the A/V quality throughout rigs that were plugged into them.

    I'll report back later.
  25. skiltrip macrumors 68030

    May 6, 2010
    New York
    That high pitched sound you hear when moving your mouse around is a ground loop issue. And has nothing to do specifically with your iMac. My old PC tower did this as well. You need to ground your power amp or powered monitors with something like the HumX. you can get it from

    I put that between my power amp's power cord and my wall socket, and the noises went away forever. I haven't had the problem in years since I got the HumX.

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