No sound when using optical out (spdif/toslink)

Question

No sound when using optical out (spdif/toslink)

I have an iMac 21" and when connecting a spdif/toslink cable to my surround receiver I get no sound at all.

I can see red light when I disconnect the cable from the surround receiver. Using the exact same cable and exact same receiver in the same port, it works when connected to my Airport Express and it works when connected to my Apple TV.

I have looked in the "Audio MIDI Setup.app" and it says Source: Digital Out, Format: 44100,0 Hz, 2ch-16bit.

Does anybody know what the heck is going on?

iMac8,1, Mac OS X (10.6.4)

Posted on Aug 15, 2010 12:08 PM

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Answer 1

den.thed

Level 10

91,798 points

Aug 15, 2010 12:21 PM in response to Nicolai Henriksen

Hi Nicolai

Welcome to Apple Support Communities

Open System Preferences > Sound and see if the Output is switching when you insert the Cable?

You might also try a different Toslink 3.5mm adapter or cable w/3.5mm end.

examples:
http://www.optimization-world.com/details/prodid/218.html
http://eshop.macsales.com/item/Newer%20Technology/CBLAOPTMT/

Dennis

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Answer 2

Aug 15, 2010 12:25 PM in response to den.thed

Yes and yes.

Output changes when inserting and removing cable.

Tried two different cables, one bought through apple.com with an adapter and one with the right end from the beginning. Both cables work just fine with AppleTV and with Airport Express, none work with the iMac.

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Answer 3

den.thed

Level 10

91,798 points

Aug 15, 2010 12:36 PM in response to Nicolai Henriksen

Recheck your Audio MIDI Setup > Output, is the Source set back to Headphones instead of still out to your Airport Express or Apple TV?

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Answer 4

Aug 15, 2010 12:41 PM in response to den.thed

I am sorry, but that does not make sense to me.

When I plug the cable into my iMac the Source go from "Internal Speakers" to "Digital Out" and when I unplug it goes back to "Internal Speakers".

When I mention Apple TV and Airport Express it has nothing to do with my iMac but is just a check that the cables and the surround receiver are ok.

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Answer 5

den.thed

Level 10

91,798 points

Aug 15, 2010 1:06 PM in response to Nicolai Henriksen

"Headphone" sorry my bad, Digital Out.

I was just checking, OK good the micro switch inside to Output Port is working.

Was this setup working and just now quit or is this the first time you have tried the iMac's Digital Out port?

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Answer 6

Aug 15, 2010 1:07 PM in response to den.thed

Ah ok.

This is the first time I try to use my iMac digital out. So I guess the hardware could be defect but I do see bright red light in the other end of the cable so something is working.

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Answer 7

den.thed

Level 10

91,798 points

Aug 15, 2010 1:20 PM in response to Nicolai Henriksen

Check all of your output levels, the iMac's main, iTunes (if that's what your using) and your surround receiver's input level?

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Answer 8

Aug 15, 2010 1:22 PM in response to den.thed

Well, when connecting the optical cable all the output levels on the iMac is disabled.

On the receiver it seems like it does not even recognize the input - the display blinks "optical" just as if the cable is not even connected. When connecting another optical source (e.g. a dvd-player) the "optical" on the receiver stops blinking.

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Answer 9

den.thed

Level 10

91,798 points

Aug 15, 2010 1:29 PM in response to Nicolai Henriksen

With everything connected, goto the Sound Preference or MIDI Setup and see if the Mute box is checked?

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Answer 10

Aug 15, 2010 1:39 PM in response to den.thed

Well whenever the cable is in the volume and mute buttons are grayed and cannot be changed.

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Answer 11

den.thed

Level 10

91,798 points

Aug 15, 2010 2:43 PM in response to Nicolai Henriksen

The only other things I have to offer at this point are:

resetting the SMC > http://support.apple.com/kb/HT3964

the PRAM > http://support.apple.com/kb/HT1379

and creating a new User Account to see if the Output works in it.

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Answer 12

Aug 15, 2010 2:55 PM in response to den.thed

Ok thank you for your effort. I will try your suggestions.

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Answer 13

Aug 15, 2010 4:03 PM in response to Nicolai Henriksen

Same symptoms here. I have tried all of the above advice in vain.

Since upgrading my MBP C2Duo to 10.6.4 my toslink "digital out" seams to have stopped working. No changes in setup: cables & receiver have been verified to work since. Receiver is not receiving anything. Audio Midi Setup changes from "Internal speakers" (working fine) to "digital out" when connecting the toslink but the receiver is not getting any stream. The toslink shows red laser light when disconnected at the receiver, but no sound. Headphones work just fine.

Read about other sound issues due to the 10.6.4 update in other threads & forums. Could this be a 10.6.4 update issue as well? Very frustrating to say the least...

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Answer 14

Aug 15, 2010 11:18 PM in response to ThrowAwayHero

Aaah. Not me going nuts then. That is a little bit comforting to know - having a little kid to raise.

Could very well be a 10.6.4 problem, although I have no way of confirming short of re-installing. And that is a bit too much work.

Thank you a lot.

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Answer 15

Sep 8, 2010 6:21 AM in response to Nicolai Henriksen

I'm suffering from the same problem. It's the first time I've tried to use the optical out, so can't say whether it's a 10.6.4 issue or a pre-existing one.
The iMac output auto-switches when an optical cable is plugged in and the far end illuminates in red, but the receiving device (a now ancient Sony MZ-R30) can't see it ("no signal"). Taking the output from a CD player instead, the same cable and recorder combo is quite happy.
I've even been through all of the bit-rate and bit-depth permutations offered in Audio Midi Setup, with no success.

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