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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?

retiredaudioguy

Showing 3 responses by erik_squires

erik_squires
16,878 posts
 

Last post, honest.

To add to this, I live in an area where power and Internet is spotty.  One or the other or both can go out.  I use Roon for streaming.   I have a light in my office which turns on when the Internet is in failover mode to my alternate provider so I can literally watch the light and tell if I’m online or not.

The failover process however takes about 20 seconds to recognize that my primary is down before it switches over.  20 seconds.  

I’ve been happily listening to music while this has happened, and sometimes movies, without a single interruption.  

That’s how buffering works.  It pre-fetches the stream before your DAC or TV is ready for it and deals with the missing packets and broken connections in the background.  Cable quality be damned. 

The same happens when I’m driving.  I go in and out of cell service often.  So long as the song has started playing I never notice.   A much better investment is using a low noise wall power adapter from iFi to prevent the switch mode noise from polluting your AC.   I have my switch and streamer (a Raspberry Pi 5) on them.  

erik_squires
16,878 posts
 

So, doing a little research on streaming, according to Gemini, they primarily use TCP, not UDP.

As  I suspected, UDP is best used for live streaming, in cases where you would rather have the audio in real time than perfect.  Consider a video call.  Can you wait 10 seconds to hear the others in the meeting? Then use TCP. On the other hand if you’d rather suffer packet losses and be able to carry on a conversation, use UDP. 

In an audio streamer the point is moot anyway as you still get bit perfect transmission from your cable modem to your streamer.  Assuming UDP or TCP.  The de-ionized, cryogenic, thrice blessed cable you use for the last 2 meters won’t change a single bit.  Besides in a bad Wifi environment, any packet losses are going to happen long before your home.

What does matter is the quality of the buffering in the streamer, and how well the clock on the DAC is able to get data when it wants it without a conflict with the input stream.  

erik_squires
16,878 posts
 

This is crazy.  Only the quality of the coax coming into your home affects the sound.  You need to try 3-4 different Internet providers and ask them which brand of coax cable they use to make an informed opinion. 

OK, that's a joke.  What's real is my blog on protecting your network from lightning surges is now online.  Enjoy. 

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