Video killed my audio stars

February 16, 2009 4:43 PM

Plugging in an external monitor to my Macbook Pro kills the audio. What's up with that? And is there a solution that does not involve an expensive USB audio product?

My Macbook Pro is attached to a stereo system, which has worked just fine and dandy...until I plugged in a DVI cable and suddenly the audio was almost overwhelmed by static and "machine noise" (e.g., there are changes in the sound when I press keys or scroll windows). I usually associate this with poor shielding on cheap sound cards...what's up with my Macbook?

More importantly, is there anything I can do to fix this? I'd really like to be able to use an external monitor. One solution is some sort of external USB-connected audio device, but I'm not entirely sure what my options are...the only things I've found are (a) headphones, when what I really want is 1/8" stereo out, or (b) audio input devices like the M-Audio FastTrack (which also support audio out). I don't want just headphones, and I don't need anything as fancy as the USB connected devices I've found.

Thanks for your suggestions!

posted by larsks to Computers & Internet (8 answers total)

Are you certain the monitor doesn't have an audio output of its own? If so, channel the sound through that way.

This is super cheap, although I can't vouch for its quality.

Finally, these guys will definitely have an answer if someone here doesn't.
posted by fantasticninety at 4:48 PM on February 16, 2009

Have you tried calling Apple? Sounds like a hardware defect.
posted by wongcorgi at 5:13 PM on February 16, 2009

Also, if its out of warranty, you can pick up USB sound output devices for around $10 on newegg. I have a bunch that I keep around, and they dont require drivers for OS X or windows.

http://www.newegg.com/Product/Product.aspx?Item=N82E16812186046
posted by wongcorgi at 5:16 PM on February 16, 2009

When this happens, what do you see in the output tab of the Sound preference pane (Apple Menu->System Preferences->Sound)? The solution to your problem may be as simple as selecting the correct output (in my system, it's called "Internal Speakers|Built-in Audio"). OS X should remember this preference next time you plug in the monitor.
posted by strangecargo at 5:44 PM on February 16, 2009

Response by poster: odinsdream: the noise is independent of whether the computer is plugged in or not. I'm reasonably certain this isn't a grounding-loop sort of problem; the noise isn't the sort of hum I would expect from that.

strangecargo: It's already using the correct output. That's why it's been working for all these months!

fantasticninety and wongcorgi: Thanks for the product suggestions!
posted by larsks at 6:56 PM on February 16, 2009

FWIW, I use the iMic with my iMac and it works really well. Never a problem. It even sounds great when I record old tapes and records through it's input.
posted by thebigdeadwaltz at 7:50 PM on February 16, 2009

If I understand your setup, you should be able to solve this problem for about three bucks.

My Macbook Pro is attached to a stereo system…How? Are you plugging the stereo into to audio out port (headphone port) of the Mac using mini RCA jacks and a splitter cable to separate the left and right channels?

If so, help is two millimeters away. That same audio out port on the Mac is a "Combined optical digital output/analog line out (minijack)" port. What you're getting now is analog audio. But buried slightly deeper in that port (so the minijack won't damage it) is a Toslink digital fiber optic jack. Just buy the proper adapter, and connect your stereo via the digital output. (Hope your stereo has digital fiber optic input).
posted by dinger at 4:47 AM on February 17, 2009

I second "hardware defect." I've had many Apple laptops and never had this problem. (And I routinely plug in an external monitor while listening to audio through an external speaker system.)
posted by raf at 5:38 AM on February 17, 2009