Cinema Display 24 sound problems

(This post also appears over in the MacBook Air Forums)

I’m having a problem even the Apple Product Specialists can’t figure out and am hoping someone here can think of something that might help.

I bought an Air in July and set it up successfully with my old Dell monitor and external speakers (headphone jack). In Sept I bought the Apple 24” LED display (from now on called display). A couple of days after setting it up, the display’s speaker’s started to make a horrible noise. Kind of like a blown amp; kind of like bad radio static. Happens with both audio streamed through Firefox and music played from my iTunes library. Once it starts, it doesn’t stop. The only way to fix it is to go to System Preferences>Sound and toggle over to internal speakers and immediately back to display usb audio. It is instantly repaired and fine again for another day or so. You can hear the audio through the static, but not very clearly. The Air is powered through the display and the display is plugged into a UPS.

To date we have tried:
3 displays - all same problem
2 Airs - same problem
Disconnected all peripherals leaving Air and display only - same problem
Wiped the drive and reinstalled the system - same problem
Tested the house power at the outlet - 120 volts
Purchased brand new APC UPS with line conditioning - same problem
Connected external USB speakers - works fine

My system is pretty simple: bluetooth keyboard, usb mouse, wireless printer, Western Disgital usb drive for Time Machine and a ScanSnap Scanner. The problem happens with or without these connected and with just Thunderbird, FireFox and Adium installed (along with the Apple apps). I can't create it on demand, so taking the Air and Display to a Genius Bar won't help (unless they keep both and listen to audio for a day or two).

I’ve spent about 50 hours (not kidding, really) working with Apple to diagnose this and we haven’t come up with anything. I googled everything I could think of and searched these forums. The software folks in my life are stumped but think it might be some kind of buffer since it takes a while to create and can be instantly “cleared” by switching speakers.

Right now I still have both of the Airs that I can use for testing. If anyone can think of something for me to try, I’d sure appreciate the help. I really don’t want to end up with a $900 monitor whose built-in speakers I can’t use. Thanks in advance

Hi,

I just want to *LINK ANOTHER THREAD* where we are discussing this.
It may be helpful to others...

_2 known quick fixes :_
1. go to sound preference select another sound source...then go back to internal speakers
2. unplug and replug the usb cord connected to your portable mac (Macbook, Macbook air, macbook pro)

_2. possible solutions :_
1. get a better UPS power supply (maybe a power source problem)
2. simplify connections to the back of the display... especially hubs plugged into the cinema display usb hub. make sure all hubs are powered (if being used)

*LINK (please read) :*

http://discussions.apple.com/thread.jspa?messageID=10473201#10473201

Very strange... I just posted another topic here for my similar problems:
http://discussions.apple.com/message.jspa?messageID=10742036#10742036

It seems that there are several issues with Snow Leopard 10.6.2 and 24" Led Cinema Display. Hope that Apple fixes this annoying bugs: Sound-related problems and black screen for some seconds.

Message was edited by: Francob

Only a suggestion but it could be worth connecting it to another Mac to see if it's the display or the Mac. It's also worth downloading the 10.5.8 Combo update and installing that to rule out software. The fact it works once you unplug it and plug it back in would make me think it was more software.

I have the exact same issue. Let me provide some more information.

I happen to have Cinema Displays 24s -- one at home and one at work. They were purchased about a month apart. The one at work works flawlessly. The one at home exhibits the same flaw belreve notes -- after a period of use, the sound get very quiet and distorted. The only solution is unplugging the power from the back and plugging it back it. It then returns to normal operation immediately.

I believe the problem is related to the Display, as I am using the same MacBook with both of my Cinema Displays and only one of them has the issue.

Have you figured out a solution?

I'm having a similar problem here.
Apple Cinema Display 24-inch and 2nd gen Macbook Air.

The display sound becomes distorted after some period of use. The only solution is to unplug the USB cable and plug it back into the MBA.

I'm thinking this is a Snow Leopard problem as it never happened with Leopard.

I've had the same issue and the only solution was to unplug the power cord to restore the sound.

I also believe this is a Snow Leopard bug as I noticed a number of issues with the sound in iChat when everything worked perfectly with Leopard.
J.

Just want to add to the chorus. My 24" cinema display, plugged into my mac pro just gives up on sound at random intervals (again started a few weeks back). I hadn't tried unplugging the usb, i usually just restart the system to get it working again.

Audio through all other outputs works fine (ie. built in speaker, headphones).

My variation is that I'm still using Leopard, so its probably not a Snow Leopard issue.

I'm cursed. Just after I posted that I hadn't had any trouble in 5 days, there it goes again. So, better power might make it less worse, but it doesn't seem to make it go away completely.

Back to the drawing board.

I have just started experiencing this issue for the first time this evening.

Its too soon to say whether this is the fix (that worked for me on this one occasion), but I was running parallels in the background and when i moved the MBP away (disconnected it from the display) and then reconnected it, the sound problems began as described above.

I looked in the Parrallels screen and discovered that it had been trying to add a new USB device but had issues. I closed down Parallels and the issue corrected itself.

Are any of you guys running Parallels when this happens?

Regards

Hi,

I'm having exactly the same problem. After a while the sound gets distorted and "crackles", and this can be fixed by unplugging and plugging back in the USB connector between the display and the computer. I'm in a Gen-C MacBook Air on Snow Leopard.

I had this problem and brought the display back, and got a new one. Then the problem was even worse with the new one. So I returned it, but they asked if I could come back and see a tech the next day, as they were about to close, and that was fine with me.

Then, plugged it in again and have had absolutely no problems since. And I missed my appointment.

The only thing I changed was to plug the display USB chord directly into the MacBook USB, then everything else into a peripheral USB. It's a fantastic display and I use it for everything; sounds works great too.

Same problem since I installed 10.6.2, but probably just a coincidence. I only have an iPhone connected to the 24 Cinema Display USB, which I purchased just a week ago. Sound was OK in iTunes, but in YouTube (either in Safari or Firefox) the sound was stuttering.
Unplugging the USB connector on the MBP solves it temporarily. Buffer problem?

I have a Macbook Pro with Snow Leopard 10.6.2 attached to a Cinema Display 24.
itunes plays thru the display speakers as do dvds. Some online content
plays with sound thru speakers - but you tube videos have no sound !!! (If I
disconnect the usb connection the sound comes thru the macbook )
Genius Bar reinstalled operating system and most recent updates-did not help
Frustrating to have spent so much on Cinema Display and not have 100%
performance. Appreciate any suggestions

I agree with you tifthebag. If my cinema display was not working at 100%... who needed it?

I certainly don't, and for me, reinstalling the operating system was not even an option. I could do it, but at these prices there was just no way.

The only thing I really did differently was plug the USB chord coming out of the display itself, directly into the USB port on the Macbook Pro. It's so simple I felt dumb initially. I have nothing in the USB port to the display, everything else is on a hub in the other USB port of the MBP.

But that was evidently the problem. Works great. I hope you're solution is as simple and easy!