TOSLINK Distortion

davechen · 8035

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Offline davechen

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on: April 19, 2015, 04:44:04 PM
I am also having sound problems with my DAC.  I have only been using the Toslink input hooked up to my Oppo 103 blu-ray player.  On 44.1k audio it sounds great.  However on high bit rates it sounds static-y.  When I first started trying it out, it did play 96khz fine, but in the past week or so, anything not CD-rate has not played correctly. 

I've tried unplugging the DAC to try and reset it, but that doesn't seem to change anything.

I could try and record the sound if that would help.


Offline Doc B.

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Reply #1 on: April 20, 2015, 05:20:02 AM
I believe this is the first report of an issue with TOSLINK. Best place to start is to determine if it is an issue with the source, the cable, or the DAC. Do you have another TOSLINK source to try? Or another TOSLINK input DAC to try with your source? About three DAC prototypes back I thought I had a DAC problem that turned out to be a flaky TOSLINK output on my Mac. Had to determine that by trying a DVD player with the DAC.

Also, are you seeing the sample rate change on the display when you play 96K files?

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Offline fullheadofnothing

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Reply #2 on: April 20, 2015, 06:52:01 AM
The issues I have run into with distortion on TOSLINK related to sample rates have resolved themselves if I simply let it play for about 30 seconds. How long have you left it playing? I have also been able to clear it by power cycling the DAC. You said you unplugged the DAC, do you mean power, or the TOSLINK? Have you power cycled your source when you have the issue?

Dan's comments about trying another source is a good one. Additionally, have you successfully used this source with other DACs and the files that you are using?  Cabling should also be examined (for instance, the Oppo has coaxial and optical outs, have you tried both?)

Finally, how is the DAC situated? We have noticed some temperature related flaky behavior when we have left a DAC sitting on top of a DVD player.

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Offline davechen

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Reply #3 on: April 20, 2015, 07:58:19 AM
I power cycled the DAC, and I did see the display change to 96 (or 48 for audio fed from my Tivo).  I didn't power cycle the blu-ray player, but I can try it.  The DAC is sitting on one shelf of my rack all by itself, so I don't think it'd be a heat issue.

I can try the other TOSLINK device I have, an Apple TV.  I only have one TOSLINK cable.  I don't remember where I got the cable, but it's a no name cable.  I'd been using it with my previous DAC (MHDT Paradisea+) without any issue.  I didn't really try much hirez audio with my old DAC, though. 

Maybe I'll order a new TOSLINK cable.  Do you have any recommendations?

I didn't let the distorted audio play for very long, so when I get home I'll try letting go longer.

I can also try USB, although I use a Mac running OS X 10.10.3, so it sounds like there might be issues.  I do have an older Macbook Pro I could try.  Can't recall what OS it has, but I haven't updated that one in a while.


Offline fullheadofnothing

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Reply #4 on: April 20, 2015, 08:42:10 AM
We have mostly used Monoprice TOSLINK cables; their cheapest 3 foot is part number 1447, 6 foot 1419. If you want to use your AppleTV, I think it needs the converter end, which they also sell (p/n 2671). You definitely need that converter for TOSLINK from a Mac. They also have BNC-RCA cables in various lengths (p/n 622 for 3 ft, 623 for 6ft) if you want to try your coax output. All this will set you back about what the BNC-RCA adapter costs at your local RadioHut.

Definitely try letting it play for longer. That was the easiest fix I found. I generally found this issue would resolve with a quick power cycle; my theory (and somewhat confirmed by John Swenson) is that it is an issue with clock sync, and so power cycling re-clocks to the stream as long as the stream keeps playing when the power is cycled. Powering down for a bit longer may prove more useful for you, as it has with other issues (when I was working with this issue, I was keeping the DAC off for a few seconds). I would recommend keeping the high resolution stream going when attempting any power cycling activities.



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Offline Bob

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Reply #5 on: April 20, 2015, 04:24:18 PM
The AppleTV does not need the converter (the 3.5mm mini connector) -- it has the standard optical cable output.  ;)

Bob S

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Offline davechen

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Reply #6 on: April 20, 2015, 05:46:57 PM
I'm suspecting it's inconsistent connection with the cable.  I plugged it into the Apple TV and got similar sound problems.  Then I put it back in the blu-ray player and it seems to work fine at 44.1, 48 and 96 hz.  I'm guessing the cable might not always be getting seated well. 

So far right now, it seems to be working fine. I'm going to order one of the Monoprice cables.  Hopefully that one will connect better.


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