Which BNC 50-ohm cable for NHB-108 and NHB-18NS interconnection

[Zeotrope]

Any comments about dCS acknowledgment that XLR is the better measuring and sonically superior output on their units?

My post #94 above goes into more detail

I don’t think you will ever get that. XLR has ~2x more components in the signal path vs unbalanced. And certainly on the input side, DarTZeel recommends unbalanced (as do most if not all high end manufacturers who have compared the sound).

XLR cables for an unbalanced signal is probably the best of both worlds, as you get some additional noise suppression from the 3rd conductor - but then it’s cable dependent.

 

[Rob77]

Yes, it’s just a different connector, no change to the signal.

Exactly

 

[Zeotrope]

Rob, any tricks or tips on how to replace the BNC with RCA on the 2.74mm H+S coax?

 

[Rob77]

Rob, any tricks or tips on how to replace the BNC with RCA on the 2.74mm H+S coax?

I used top of the line Furutech RCA connectors (CF-102 NCF) since they are very well built and offer a very convenient space for big cables, and the cable itself does not need soldering but is secured with screws. It is necessary to be precise with the length of signal and ground conductors, so that they enter precisely. Ground conductor is shorter and signal conductor is longer. It may also be necessary to slightly thin the polyethylene section of the cable to make it fit within the plug, being very careful to not to thin it to much to avoid shorting signal and ground. The insulation should also be trimmed only for the length of the cable that goes inside the connector, again to avoid shorting the conductors. Once the connectors are in place on both ends of the cable, it is always advisable to use a tester to be sure cables are not shorted.
It seems complicated, but in the end is quite easy...you just need some basic manual skills.

 

[Zeotrope]

Thank you, @Rob77, much appreciated.
You can test for continuity or shorting on a single (RCA) connector, correct? Just see if the inner and outer conductors are shorted?

 

[Rob77]

Thank you, @Rob77, much appreciated.
You can test for continuity or shorting on a single (RCA) connector, correct? Just see if the inner and outer conductors are shorted?

Correct, you test each channel (right and left) separately checking continuity from BNC to RCA, both on signal and ground.

 

[Zeotrope]

Correct, you test each channel (right and left) separately checking continuity from BNC to RCA, both on signal and ground.

Thanks. The cable is too long to connect a voltmeter to each end, but I can check one connector at a time. If it's shorted, then I suppose it will be detected on a single connector, since the outer and inner conductors will pass current.

 

[Rob77]

Thanks. The cable is too long to connect a voltmeter to each end, but I can check one connector at a time. If it's shorted, then I suppose it will be detected on a single connector, since the outer and inner conductors will pass current.

Yes, it would be better in any case to check both ends correctly. Cannot you bend the cable and have the connectors one near to the other?

 

[Zeotrope]

Yes, it would be better in any case to check both ends correctly. Cannot you bend the cable and have the connectors one near to the other?

It's a 10m length that is already affixed to the wall and running behind some components. But I can get a longer test lead for the voltmeter. I will do that, thank you.

 

[Rob77]

It's a 10m length that is already affixed to the wall and running behind some components. But I can get a longer test lead for the voltmeter. I will do that, thank you.

Let me know the result!

 

[Zeotrope]

Let me know the result!

Will do!
Will be using Crystal Cable silver RCA.

 

[struts]

Yes, it’s just a different connector, no change to the signal.

The connector does not change the signal per se but it does have an impedance so if it is not matched it will cause signal reflections. For BNC connectors there are both 75Ω and 50Ω variants, the principal difference being the thickness of the dielectric:



However I am not aware of any 50Ω RCA connectors (happy to be proved wrong here). Standard audio RCA interconnect cables and RCA plugs have an impedance of 75Ω - and yes, that includes the RCA output socket on the dCS DACs. Using any 75Ω parts in a 50Ω cable will cause signal reflections. Now I have no way of knowing what difference this will make/how much it will affect sound quality etc., but any such cable will not be 50Ω impedance matched like the Zeel which somewhat defeats the object of the exercise.

Despite generally preferring not to use adapters, the only way I am aware of to make a 50Ω RCA-to-BNC cable is to use a 50Ω cable terminated with 50Ω BNC connectors and a 50Ω BNC-to-RCA adapter like this one for the RCA end. I suggested this to a fellow dz owner for connecting his Rossini to his NHB-18 NS and he was very happy with the results.

 

[struts]

Any comments about dCS acknowledgment that XLR is the better measuring and sonically superior output on their units?

My post #94 above goes into more detail

Only that my ears agree (I have only compared XLR to RCA, not a RCA/Zeel hybrid). Like you my XLR cable happens to be a couple of rungs down from my RCA from the same manufacturer but even with the field tilted against it using the balanced output of the Vivaldi to drive the NHB-108 Model 2 sounds clearly superior to the single ended. I would expect this to outweigh the benefits of impedance matching but this is pure speculation. The only way to know for sure is to compare two cables at similar price points. It is impossible to compare with exactly the same cable due to the differing impedances.

 

[Zeotrope]

The connector does not change the signal per se but it does have an impedance so if it is not matched it will cause signal reflections. For BNC connectors there are both 75Ω and 50Ω variants, the principal difference being the thickness of the dielectric:

View attachment 138730

However I am not aware of any 50Ω RCA connectors (happy to be proved wrong here). Standard audio RCA interconnect cables and RCA plugs have an impedance of 75Ω - and yes, that includes the RCA output socket on the dCS DACs. Using any 75Ω parts in a 50Ω cable will cause signal reflections. Now I have no way of knowing what difference this will make/how much it will affect sound quality etc., but any such cable will not be 50Ω impedance matched like the Zeel which somewhat defeats the object of the exercise.

Despite generally preferring not to use adapters, the only way I am aware of to make a 50Ω RCA-to-BNC cable is to use a 50Ω cable terminated with 50Ω BNC connectors and a 50Ω BNC-to-RCA adapter like this one for the RCA end. I suggested this to a fellow dz owner for connecting his Rossini to his NHB-18 NS and he was very happy with the results.

Good info, thanks.

In my case, I am no longer using the DarTZeel 18NS and 108, but will continue to use the 10mm Zeel cable, so changing the BNC to RCA is not going to matter. Impedance of my new preamp is ridiculously low < 0.2 ohm, so the cable and connections really does not matter.

THANK YOU for the adapter link! I was just looking for adapters earlier today. Will use these until I get the silver RCA Crystal Cable units installed.