TC-7520 - what kind of cable for S/PDIF via electrical coax?

[NRG]

BTW some old threads on DIYAudio question the validity of the Canare 75Ohm claim as the dimensions of the RCA mean the impedance can't be met...

[Ali Tait]

One way would be to solder a 75ohm resistor on the signal wire between the coax and rca.Might be worth trying and see if there's a difference.

[chrism]

BTW some old threads on DIYAudio question the validity of the Canare 75Ohm claim as the dimensions of the RCA mean the impedance can't be met...

Hi Neal,

I have compared the Canare connector solution with soldering the cable straight through to the board and could not detect any difference to the sound.

Have you come across something better that you would like to share?

Regards

Chris

[Quietschbox]

The reason the cables apparently sound different is due to reflections because of the none optimum termination. Terminate SPDIF correctly and these differences magically disappear.

Thorsten, when he used to post a lot on the various forums demonstrated that 1.5m was a good cable length choice with RCA connectors or use an very short cable IE ~15cm

Hi NRG, thanks for explanation. Looks like a potential Vodookiller.
I'll dig that and do a search.

[NRG]

Hi Neal,

I have compared the Canare connector solution with soldering the cable straight through to the board and could not detect any difference to the sound.

Have you come across something better that you would like to share?

Regards

Chris

Yes, BNC plug and socket.

[chrism]

Yes, BNC plug and socket.

Hi Neal,

Not certain how this would improve on soldering straight to the board but it is a solution. Hacker did the BNC soln to his Squeezebox on PFM.

I think I will stick with the Mark Grant cable with the Canare connectors as it does the job well in my opinion and is a cheap solution.

Regards

Chris

[Quietschbox]

http://www.positive-feedback.com/Issue14/spdif.htm
http://www.epanorama.net/documents/audio/spdif.html

Two articles i found. Didn't finish them yet.

I am confused on wave impedance=75 Ohm and termination resistor 75 Ohm.
So far i assume that any (video/TV) cable with wave impedance 75 Ohm will be fine and do, but what about termination with 75 Ohm resistor? Isn't that a confusion with the cable impedance and thus unneccessary?

And talking 75 Ohm resistor termination, does the TC-7520 have these built?

[StanleyB]

Many people confuse resistance and impedance.

[Quietschbox]

http://www.positive-feedback.com/Issue14/spdif.htm
http://www.epanorama.net/documents/audio/spdif.html

Two articles i found. Didn't finish them yet.

I am confused on wave impedance=75 Ohm and termination resistor 75 Ohm.
So far i assume that any (video/TV) cable with wave impedance 75 Ohm will be fine and do, but what about termination with 75 Ohm resistor? Isn't that a confusion with the cable impedance and thus unneccessary?

And talking 75 Ohm resistor termination, does the TC-7520 have these built?

Quote:
S/PDIF (or Sony/Philips Digital Interface) is a digital signaling standard specified at 75 ohms characteristic impedance and terminated on both ends. This means that the source driver (in the Transport) must have an output impedance of 75 ohms and the receiver (in the DAC) must have a parallel resistive termination of 75 ohms. If these terminations are both set to 75 ohms, then ideally the signal will propagate from the Transport to the DAC and no reflections will occur on the transmission-line that connects the Transport to the DAC, assuming that all components of the transmission-line are also 75 ohms.

Summary:
Terminator1(75 Ohm)--------cable(75 impedance)----------Terminator2(75 Ohm)

[leo]

I've just made a 1m S/pdif cable using 1694A terminated with 75R BNC's.

Tried with two different dacs AYA and Sabre the results was quite interesting, the sound was a little warmer with the 1694A, it gave the impression of slightly less dynamics

Cable I normally use is 1505A terminated with 75R BNC's
, I may have to try other alternatives too