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Topic: Problem with Digital Audio Out from Mac Mini (Read 19112 times) previous topic - next topic
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Problem with Digital Audio Out from Mac Mini

Reply #25 –
Quote from: pgm234 on
The advantages of going the ATV/iTunes route are: (1) hopefully the ATV output solves my optical input problem; (2) I get to use the features of ATV (I'm just not sure I need/want any of them); (3) I have an all-Apple solution so hopefully future technical issues are minimized, as opposed to a mix of systems and apps; (4) the ATV user interface is easy and my wife will like it.


A noticeable difference between Apple TV and Airport Express is the lacking of analog line level output in the ATV. I don't know if the ATV will solve the optical link issue, but surely with the AE you could get rid of it using its analog output to drive your preamp. About the overall quality of this solution, of course, it's up to you to decide if the AE internal converter can take the place of the preamp one in your setup. Anyway, knowing the first and not the latter, I can only hypotize that you're not going to notice many differences, if any.
... I live by long distance.

Problem with Digital Audio Out from Mac Mini

Reply #26 –
I still see both AE and Apple TV for $99 at Apple. Are you guys probably seeing the refurbished prices? I bought a refurb AE on ebay for about $60 IIRC.

Problem with Digital Audio Out from Mac Mini

Reply #27 –
Quote from: andy o on
I still see both AE and Apple TV for $99 at Apple. Are you guys probably seeing the refurbished prices? I bought a refurb AE on ebay for about $60 IIRC.


Here, in Italy: Airport Express 89,00€ - Apple TV 119,00€.
The dish of pasta all'amatriciana I've just eaten: 3,50€.
... I live by long distance.

Problem with Digital Audio Out from Mac Mini

Reply #28 –
I installed Apple TV last night and ran its digital/optical output to my preamp and the problem did not go away.  My preamp still loses sync and takes just long enough that I don't hear the first second or so of the next song. 

So that leaves me with the alternate solution of either using the 3.5mm-to-RCA splitter off my Mac Mini, or buying an external USB DAC, and running analog R/L audio to my preamp.  AE doesn't gain me anything because my Mac Mini is located next to my preamp and I can just as easily run the analog direct from my Mini.

I'm going to try to contact McIntosh to see if they know of any solutions, but with such an old preamp I'm not optimistic.  They'll probably recommend upgrading to a new one but if I did buy a new one I can't afford their model.

Problem with Digital Audio Out from Mac Mini

Reply #29 –
Strange issue, i have an Apple tv connected to my HK amp no issues and even my NAD has no issues. Deff seems like an issue with your amp.

I would just go from 3.5mm-to-RCA splitter to your preamp, that way you can use the MacMini's volume.  It's all going to sound the same. Great quality. No scientific test i have tried many ways of connecting  to the amp and to me they honestly all sound alike.

Too bad the Apple Tv didn't solve the issue, there is really nothing on the Mac that has a UI and good as the Apple TV for music.

Problem with Digital Audio Out from Mac Mini

Reply #30 –
Quote from: Billytheonion on
Strange issue, i have an Apple tv connected to my HK amp no issues and even my NAD has no issues. Deff seems like an issue with your amp.

I would just go from 3.5mm-to-RCA splitter to your preamp, that way you can use the MacMini's volume.  It's all going to sound the same. Great quality. No scientific test i have tried many ways of connecting  to the amp and to me they honestly all sound alike.

Too bad the Apple Tv didn't solve the issue, there is really nothing on the Mac that has a UI and good as the Apple TV for music.


A few people told me that Apple TV worked for them, so I'm pretty sure it's just the slowness of my old preamp. I bought it back in 2001 so maybe it's just too slow to handle the input properly.

My wife loved the Apple TV UI. I thought it looked really good and was simple and straightforward, but I don't mind using the full iTunes. With so many artists in my library it's sort of a pain to scroll using the remote. I would need to work on the tagging so I could use genres more effectively to find music.  It was really cool too how she could stream music from her iPhone, but even that had the sync issue at the start of songs.

So thank you again for the continued help, I'll work on the analog option next.

Problem with Digital Audio Out from Mac Mini

Reply #31 –
The Apple TV 1 will deff solve the issue that has analogue, maybe you could find a cheap second hand one. with the internal HDD and you can add an external, you can avoid leaving your mac on too.

Yea you must make sure the tags are done properly for it to show up on the Apple TV correctly. With the search function you can just type in what you are searching for no need to scroll down long lists. I have really found nothing that compares to the Apple TV UI for music

Problem with Digital Audio Out from Mac Mini

Reply #32 –
Finally!  The problem is solved.  I’ll document the fix here for archiving purposes in case someone in the future comes up with the same problem.  Thank you to everyone for all the help and suggestions.  Apple TV didn’t solve the initial problem, but it did make me get Apple TV which turned out to be a great purchase especially for my wife who loves it.

The problem was indeed with my McIntosh MX-132 preamp/AV Processor.  However, it was not due to the unit being “slow”, it had to do with one of the settings.

Bottom Line:  go into the MX-132’s Settings and set DTS Unmute Delay to “OFF”. 

In the words of McIntosh Tech Support:  "DTS Unmute Delay is feature from the days of the first Multi Channel digital music format: DTS Audio. Sometimes a processor will incorrectly try to decode DTS as Dolby Digital or PCM, this can cause a short burst of White noise before the processor correctly identifies the signal as DTS. To avoid this noise, DTS UNMUTE DELAY mutes for a second or 2 when a new digital format is detected or, as I suspect with your system, the digital stream stops entirely between songs and the MX132 has to once again decide what format it is looking at. So songs have the first note or so cut off by DTS Un-Mute Delay, that is why we added the ability to turn it off.”

This feature was actually added in a later software release to the MX-132, so it’s not covered at all in the manual and I could not find any online documentation.  That’s why I couldn’t find it earlier. It can be found under Option 9 in Setup (ADVANCED).  If Option 9 says “RESERVED”, it means you have an earlier software version and you need to upgrade the unit (done via the RS-232 connector in back) to get this option. Luckily mine had it, as I would have had to bring the unit in because I haven’t had an RS-232 connector in a long time.

After turning this feature off, everything worked great last night.  The by-product of all this is that I have now made the switch all the way to the Apple side, switching from Songbird to iTunes, and using Apple TV which my wife loves.  Instead of reading the more complex iTunes display and using the Bluetooth trackpad and keyboard, we just use the simple Apple remote and Apple TV to control music.  And if I want, I can switch the display to the Mac Mini and use iTunes via AirPlay and that works great too.

Thank you to everyone for all your help and patience as I worked my way through this issue. 

Problem with Digital Audio Out from Mac Mini

Reply #33 –
Fantastic news, turned out all excellent in the end.

I also love the Apple Tv for streaming music, the UI is so well thought out and works with iTunes seamlessly.

You can also use your iPhone to browse your music and airplay it to the AppleTV.

Problem with Digital Audio Out from Mac Mini

Reply #34 –
It seems that S/PDIF modules built in personal computers or home theatre systems have a very annoying energy saving feature : at the shortest, slightest perfect pause they switch off transmission - and they need 500-800 milliseconds to restart transmission. It's a big shame to the audio industry, and manufacturers are okay with this.

So my final solution was to write an application, that generates an absolutely unhearable tone - 200 Hz, 8 bits per channel, pulse levels are 0 and 1, volume is 1 percent - I maxed out my LG home theatre system's volume, and I couldn't hear it - and it keeps the S/PDIF module alive, no more pauses, breaks, silences, everything is fine.

I put it up on the Mac App Store : Optical Audio Port Keepalive