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0.3 m or 1.5m Word.clock BNC cables for best performance?


Beolab
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Have read all sorts of articles and forums, about reflections in a Spdif / word.clock cables. 

 

50% of the Electro Engineers articles state that you should use as short word.clock cable as possible to mimic as if it was one unit on the same cirut board between a D/A / A/D converter and a master clock generator. 

 

And 50% states buy messauring the the reflection of the word signal will bounce between the transreciver and master clock generator if the cable is shorter than 1.5 meters in length, and you will get higher jitter and phase loops because of the reflections. 

 

This is stated for SPDIF , but i wounder if it the same roule for a word.clock signal transfered in a BNC 75 Ohm cable? 

 

I am about to upgrade my word.clock cables to pro versions but befor i buy i wanted some clarification about this. 

 

Hope someone with knowlage and experience can help out. 

 

 

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4 minutes ago, Beolab said:

Have read all sorts of articles and forums, about reflections in a Spdif / word.clock cable. 

 

50% of the Electro Engineers articles state that you should use as short word.clock cable as possible to mimic as if it was one unit on the same cirut board between a D/A / A/D converter and a master clock generator. 

 

And 50% states buy messauring the the reflection of the word signal will bounce between the transreciver and master clock generator if the cable is shorter than 1.5 meters in length, and you will get higher jitter and phase loops because of the reflections. 

 

I am about to upgrade my word.clock cables to pro versions but befor i buy i wanted some clarification about this. 

 

Hope someone with knowlage and experience can help out. 

 

 

 

If the S/PDIF cable produces jitter, doesn't that defeat the purpose of using an external master-clock?

 

Why do you need an external master-clock in the first place?

"Science draws the wave, poetry fills it with water" Teixeira de Pascoaes

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11 minutes ago, Beolab said:

My question is if its better to go 1.5 meter or shorter with a matching pair 75 ohm pro bnc cabels.

If all impedances (output, cable, input) match, the length doesn't make much difference until it gets much longer. There are obviously some losses in the cable, so shorter should be preferable. If you have a fast scope, you can easily measure the reflections.

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We speaking theoretically, and if you take a 44.1 khz sample it is 2.85 mhz multiply by 0,66 nano seconds = 1.8 meters cable you need to not receive any phace loop or reflection on a SPDIF cable, but my question if is this is also legit on a Word.ckock signal.  

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Word clock is used both to mean transmission of a pure external clock signal for synchronize devices like DAC and an external clock. In this case it’s best to keep the clock cable as short as possible. 30 cm is better than 1 meter.

 

For transmission of a digital audio signals, like between a BLU 2 and Chord DAVE or a DDC and DAC, a bit longer cable can be used without problem IME. Some people like Steve Nugent have stated that a 1,5 meter coax cable is best, but to my ear 1 meter has been slightly better (the length of the cable depends on the rise-time of the transmitter, which can cause reflections if the cable is to short).

 

Here you can read his reasoning: https://positive-feedback.com/Issue14/spdif.htm 

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5 hours ago, Beolab said:

My question is if its better to go 1.5 meter or shorter with a matching pair 75 ohm pro bnc cabels.

 

 

If the cable and connectors have a characteristic impedance of 75 ohms, cable length should make little to no difference.

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  • 2 years later...
38 minutes ago, R1200CL said:

@Beolab

Have you found any differences in clock cables ?


Hi 

 

like @mjb concluded, if you buy a professional cable that can clearly show that the bnc plugs can carrie 75 Ohms then you will have less reflections and withstand 75ohm resistance . 

to be sure buy Canare 4k bnc , Belden , Van Damme , Oyaide , apogee , that is used in professional studios and tested. 
 

if you for instance buy a ultra high end MIT oracle MA-X cable that i use, then you can alter the resistance in the cable with the switch knob on the cable, to tweak the square wave slightly to your own satisfaction. 
 

do not use or buy the standard supplied cheap or free BNC black cables that is made in china for 1 cent, then you will end up with more reflections and a weird sound from testing. 
 

also do not use shorter cables than 1.5 meter bnc for the best result. 
 

less reflections makes the sound calmer and more gentle in the micro details and spectra. 

 

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