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all2ofme Mar 15, 2013 08:29 AM
Audio issues (optical out) on Mac Pro with 10.8
Hi all,

I'd been loving the sound of my Mac Pro (6 x 3.33GHz) out into an external DAC (made by Headroom) and a pair of Sennheiser HD800s. Great sounds. But...

Since about six months ago I'd been getting all sorts of random, very slight audio drop-outs when listening to music (I love tunes, but I don't make any of my own) in iTunes. I tried:

- listening with other software (VLC et al)
- a full, fresh re-install of 10.8.2
- 3 new optical cables
- a mainboard replacement for the Mac Pro

What's worked:
- running the DAC on USB instead of Toslink
- using my MacBook Pro as a source instead (either Toslink or USB)

...and the important one:
- going back to 10.7.5

As far as the Apple tech and I have been able to work out, there's an issue with the 10.8 driver for the Mac Pro's audio hardware that gives you very small drop-outs in delivery. The same OS and setup on my MacBook Pro is fine.

No idea if this is of help to anyone here struggling with an intermittent audio issue, but something to think about just in case!

P Mar 15, 2013 08:58 AM
Coincidentally, the 10.8.3 update released today claims to fix an audio stuttering issue.
all2ofme Mar 15, 2013 10:22 AM
I saw that, P - fingers crossed!

It mentions 2011 iMacs specifically, but I'm hoping that they used the same audio hardware and it's just that they're being economical with their release notes. Will try it this evening, all going well. I'd LOVE not to have to use USB, as I'm a bit short of ports.
jimoase Mar 15, 2013 07:22 PM
Audio and other stuttering
Until installing 10.8.3 I didn't notice audio stuttering...
But I did notice key stroke entry stuttering before being displayed and downloaded video stuttering.... all the time

Since installing 10.8.3 i have experience audio stuttering as well as keystroke and video delays.

ON the Apple Forum there is document studies of the audio delay counts in specific times.

My experience today with 10.8.x is that it represent less than Apple's finest... possibly since system 4
all2ofme Mar 28, 2013 12:10 PM
Not fixed with 10.8.3, sadly. Was good for a few days (getting my hopes up), but the glitches remain.
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