Mountain Lion problem whit spdif

[rick1982]

Hi everyone, I'm new both in this forum and in the audiophile world.

I've a problem whit the optical output on my iMac.

I bought a Dac (a Beresford Bushmaster Dac) and I connected it via toslink to my iMac with Mountain Lion Osx, now the problem: when i try to play files until 48kHz it's all ok, but when i try to play some file at 88kHz or 96 or higher the sound is distorted... or better it's not sound coming out but it seems like scratches ("scrrrr").

If i plug the toslink cable to my macbook pro with Lion all works correctly...

Can someone help me i don't want to change the Dac (or the Osx...).

Thanks all in advance and sorry for my bad bad english.

Riccardo.

[avta]

Two things to check. Be sure the Toslink is not defective. Try another if possible. Also, the Audio Midi settings ( Applications>Utilities>Audio Midi ) have to match the settings of the file you are playing. This must be done manually unless you are using another program that makes those adjustments automatically such as Audirvana Plus. There is no 88 Hz setting so you might just try 24/96 files to test your system although I believe 88 Hz files would be downsampled to 44 Hz.

[rick1982]

Two things to check. Be sure the Toslink is not defective. Try another if possible. Also, the Audio Midi settings ( Applications>Utilities>Audio Midi ) have to match the settings of the file you are playing. This must be done manually unless you are using another program that makes those adjustments automatically such as Audirvana Plus. There is no 88 Hz setting so you might just try 24/96 files to test your system although I believe 88 Hz files would be downsampled to 44 Hz.

 

Thank you for your answer, the toslink cable works perfect and also the dac (i tried with my macbook pro and Lion and all works great).

I tried both to set Audio Midi manually (matching the file's settings) and using some software (Audirvana Plus, Fidelia, Amarra, Pure Music, Bitperfect, Decibel).

I can't try another mac with Mountain Lion so i can't say if it's my iMac the problem or Mountain Lion in general...

Thank you again.

Riccardo.

[Audio_ELF]

Do you use a mini-TOSlink to TOSlink cable, or a TOSlink to TOSlink with adaptor.

 

Even though the cable works with a different laptop, maybe worth trying a different cable as it's possible that there is a slight misalignment. This is especially true if using an adaptor.

 

Eloise

[rick1982]

Do you use a mini-TOSlink to TOSlink cable, or a TOSlink to TOSlink with adaptor.

 

Even though the cable works with a different laptop, maybe worth trying a different cable as it's possible that there is a slight misalignment. This is especially true if using an adaptor.

 

Eloise

 

I use a toslink to toslink with adaptor, now i haven't another cable to try...

I try with another macbook (not pro), with Lion 10.7.3, and also work perfect...

Thanks Eloise.

[Mihnea]

My DAC has a manual oversampling rate switch, so if you play 96K files it can't do 8x, but only 4x. If I leave the switch on 8x oversampling I can only hear the white noise you're describing.

 

For me this has happened the same since Snow Leopard up to Mountain Lion and has nothing to do with the operating system.

 

The misalignment thing seems to be the only probable cause. As far as I know SPDIF has no error correction capability, only a parity bit (CRC), so it could be that up to a certain bit rate the data flow is manageable for the DAC, and after that it just loses lock or something.

[rick1982]

My DAC has a manual oversampling rate switch, so if you play 96K files it can't do 8x, but only 4x. If I leave the switch on 8x oversampling I can only hear the white noise you're describing.

 

For me this has happened the same since Snow Leopard up to Mountain Lion and has nothing to do with the operating system.

 

The misalignment thing seems to be the only probable cause. As far as I know SPDIF has no error correction capability, only a parity bit (CRC), so it could be that up to a certain bit rate the data flow is manageable for the DAC, and after that it just loses lock or something.

 

So it's a cable problem? It can't be a Dac problem, the dac does not "interpret" the data flow from mountain lion?

Thanks Mihnea

[Mihnea]

So it's a cable problem? It can't be a Dac problem, the dac does not "interpret" the data flow from mountain lion?

Thanks Mihnea

 

If you say it works on your MacBook, then it can't be the DAC. Most likely it's the cable (adaptor) or the SPDIF connector on your iMac.

 

Try another cable if you can before anything else.

[rick1982]

If you say it works on your MacBook, then it can't be the DAC. Most likely it's the cable (adaptor) or the SPDIF connector on your iMac.

 

Try another cable if you can before anything else.

 

I tried with another macbook pro (with mountain lion) and, in a first time, there was the same problem, but after few seconds all works ok. Today i'll try with another cable and other two mac (with mountain lion), if all works the problem is my iMac... or the optical out or on audio section of the logic board...

[rick1982]

Ok I solved the problem... was both the cable (G&BL 40 euros...) and the adaptor... changed both and all works perfect!

Thank so much to all!