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BlueSkyy

S/PDIF Question; Is it Uni or Bi-directional?

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I have a single source that I would like to connect via S/PDIF coax to two receiving pieces of equipment including a standalone DAC for driving headphones and a home theater video processor that is also, in effect a DAC.

 

So my question is the S/PDIF connection uni-directional (source to receiver) only and I could, therefore, just fan the one output into two or does handshaking between the source equipment and receiving equipment need to happen and, therefore, would preclude me sending the single source to the two receiving DACs?  If handshaking is necessary, I suppose powering off one or the other DAC when not in use may work as well.

 

Thanks for your thoughts!

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There is no handshake, so splitting the signal works in principle. However, since it's not officially supported, there may be issues with specific equipment. Try and see. It won't break anything.

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From the protocol side splitting the signal by a simple passive splitter is possible as S/P-DIF is unidirectional, no handshake.

On the physical side a passive splitter will cause a 3dB loss in signal amplitude and it will normally lead to reflections as there is no proper 75Ohm termination any more. As a result the signal quality is severely degraded. Most receivers will however work somehow with such a degraded signal but reflections and lower signal amplitude will increase jitter. Also in many cases a higher error rate is to be expected. Bit errors will normally be delt with by the receiver but as S/P-DIF has no redundancy such correction can only be done by interpolation leading to a loss in audio quality.

So a passive splitter will work in most cases but it will often degrade audio quality. For a good result an active splitter is recommended.


T+A developer

(*) My postings represent my private and personal opinion and hopefully are helpful to the members of this forum

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