How can different CAT5/6 cables affect sound.
While is is beyond doubt that analog cables affect sound quality and SPDIF, TOSlink and AES/EBU can effect SQ, depending on the buffering and clocking of the DAC, I am at a loss to find an explanation for how different CAT5 cables can affect the sound.
The signals over cat5 are transmitted using the TCP protocol. This protocol is error correcting, each packet contains a header with a checksum. If the receiver gets the same checksum then it acknowledges the packet. If no acknowledgement is received in the timeout interval the sender resends the packet. Packets may be received out of order and the receiver must correctly sequence the packets.
Thus, unless the cable is hopeless (in which case nothing works) the receiver has an exact copy of the data sent from the sender, AND there is NO timing information associated with TCP. The receiver must then be dependent on its internal clock for timing.
That is different with SPDIF, clocking data is included in the stream, that is why sources (e.g. high end Aurenders) have very accurate and low jitter OCXO clocks and can sound better then USB connections into DACs with less precise clocks.
Am I missing something as many people hear differences with different patch cords?
TOSLink and USB are connection systems, whereas S/PDIF Is a communications protocol. S/PDIF was developed in the early 80s, specifically to support the then-new CD format. It was never revised in the ensuing half-century (almost). It does not support either hi-res PCM or DSD. It can safely be considered obsolete at this point. |
@devinplombier incorrect SPDIF supports high resolution. Both my previous DAC Bricasti M3 and my current DAC Meitner MA3i accept high resolution via SPDIF. The Aurender N200 streamer outputs PCM 24/192 via coax out. |
I believe Aurender will output DSD via SPDIF as DOP. Some other streamers might as well. Native DSD probably only via USB I believe there are SACD transports that can output DOP via coax. Zenith is one. |
IMHO it should be obsolete. Replace it with something like WAV data over TCP with error correction, or an error correcting USB link, to completely isolate the DAC processing from jitter in the source. The DAC then buffers the data stream and oversamples, or whatever, the data words; it knows the frequency from the WAV data, and feeds the words into the DAC circuitry (chips or discrete) based on an OCXO, or better, clock. An OCXO chip costs from $25 to $250. For cheaper units a TCXO ($3) could be used. The phase noise of a TCXO can be about the same as an OCXO but the long term frequency stability is not as good. Or, go all in and use a Rubidium clock, at $2,000 for the oscillator, although, interestingly, the phase noise of the best OCXO parts is just about the same as a Rubidium clock. Esoteric's latest external clocks are now OCXO based not "atomic" Rubidium. They reduced the price from $25k to $15k. Still crazy packaging a $250 part and charging $15k, rather than packaging a $2k part for $25k. Their internal Master Discrete Clocks are also OCXO based. Google "History of OCXO" it is rather interesting, they were first developed in 1929 (!) but low cost versions have only been available this century. BTW, the SRS FS725 uses the same physics package as the prior ($25k) Esoteric unit and costs $3,995, it has both 10MHz and 5MHz outputs, nominally 50 Ω but doesn't care, the rms voltage is higher with a higher impedance load. |
