Coaxial RCA to BNC Cable from Transport to NDAC

I agree 100% on the termination. BNC>BNC is much more stable. I also learned this recently. According to Google- The obvious reason: DIN connections sound better than RCAs… The phono plug, or RCA connector, as best as anyone can remember, was designed decades ago as a direct current (DC) power connector. … The DIN plug has an impedance that is similar to the cable. It does not reflect like an RCA plug. [Jan 4, 2019](calendar:T2:Jan 4, 2019)

And yes, nutty is still my avatar on Audiogon. Thanks for the warm welcome.

I guess RCAs are cheaper, and easier to mount on smaller devices. They are pretty much universal an cheaper consumer stuff like TVs. BNC might be better in theory but nobody complained about the sound quality of the Hugo when it was all the rage.

I never got round to the Hugo but the 2qute did have BNC it was just too clinical.

Be mindful at audio frequencies there are no meaningful reflections. and audio connections for Hi-Fi are not transmission lines. The phono connection is fine… the phono connection was originally invented for an audio service point, and speaker connection interface. I have seen the theory of a dc connection but I have found no actual evidence of that… it was designed/used as a consumer audio interface to add a better sounding external speaker for early phono players from the research I did. (Somewhere on this or the previous forum i referenced the first consumer audio phonograph product that used this interface as an audio connection)

The main advantage with DIN for audio frequencies that I can see is that there is a common return connection, that is a common ground, for both channels, where as RCA/phono has a separate return for each channel. On connections, signal degradation is most likely to occur with physical contacts, stereo phono has 8 connections, stereo DIN has 6 connections. Having a common return potentially can produce a better stereo image or lower noise signal.

As far digital connections with a 75 ohm characteristic impedance, the most important consideration is the cable, then followed by the termination characteristic impedance. The latter is defined by the electronic interface, socket and plug. Now the geometry/dimensions pf phono/RCA prevent it providing a true 75 ohm CI, when connected to a socket, although there are some rather specialist plugs that claim to offer 75 ohm CI.
Having a mis matched CI, will introduce losses, and signal attenuation, and this will be frequency dependent (due to transmission line reflections). However in our applications for SPDIF this is unlikely to be problematic unless the cable itself is not properly designed, not least because of the relative low frequencies, short distance, very low power and digital (Manchester Code) signal encoding. If there are issues with the SPDIF signal transfer you will hear silence, dropouts or clicks… in the absence of that you have a stable signal transfer.
Phono is the effective standard socket for SPDIF… despite it not or very rarely providing a true 75 ohm CI… as it doesn’t really matter very much in our use cases.

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”As far digital connections with a 75 ohm characteristic impedance, the most important consideration is the cable, then followed by the termination characteristic impedance. ”

” If there are issues with the SPDIF signal transfer you will hear silence, dropouts or clicks… in the absence of that you have a stable signal transfer.”

Your conclusion is a digital cable will not have a sound characteristic so if it works all will sound the same in this application or?

Careful not to confuse ‘sounding the same’ with working effectively. A cable itself doesn’t produce a sound however cables interact to certain extents with the connected devices which may cause perturbations or sonic audio shifts from connected audio devices through out of band loading, noise and coupling effects.
However that is different from saying the cable works effectively in conveying its digitally encoded payload (in band).

I found the NDAC quite sensitive in this regard, where as the Chord Electronics DAVE for example, a lot less sensitive.

Alright get it. So your personal opinion is that yes, digital cables may change the overall sound characteristics in a HIFI system.

What digital cables do you use yourself?

I’m evaluating a quite expensive one now against a cheap one and am not sure I can tell a difference. If any my system seem to prefer the cheap one but doingg AB testing yourself that takes a minute is never an effective way of validating minor changes.

I use various, including a Naim DC1, Gotham Cable coax and regular 75ohm coax.
Personally I wouldn’t pay a lot on digital SPDIF cables. It was designed to be a low cost consumer interface, and 75 ohm is approximately the natural CI for low cost manufactured coax.

You may find sonic shifts occur as much in cheap coax as well as boutique audiophile leads.

BTW you might also find a ferrite choke clamped around the destination end of the SPDIF lead beneficial.

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Will try it out :ok_hand:

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Any feedback ?

Haven’t had time to make it happen and got caught in understanding which type of ferrite choke that would be suitable for this.

To be honest most readily available ones labelled as ‘EMI/ RFI noise suppressors’ will be fine, we are dealing with general common mode frequencies here rather than optimising around a specific frequency. It doesn’t need to be too precise. A choke effective from 30 MHz up will be fine. Sure you can fine tune later. They cost next to nothing. You can get a pack of then from Amazon with change from a tenner.

Ok :+1:What about running the cable twice through the ferrite. It lowers the range of where it’s effective right?

It would yes, not usually needed, but if you have more serious ground RF currents flowing it can be beneficial.

Rather than the clip-on clamps you can use ferrite rings which allow you to wind the cable through the larger hole several times. Naim used one on the Unitiserve power cable, presumably to isolate the inline SMPS.

Winding a coax that tightly isn’t always a good idea, some have a minimum bend radius.

Yes, and the same applies to Ethernet cables. No need to pull them tight when you loop them through a ferrite though.

Can a ferrite ring be to strong? I look at a few rings that say 1.7kg and 2.7kg strength and even up to 16kg.

Does it matter where on the cable you do the loop with a ferrite ring?

Like any ferrite, I would put it as close as possible to the device you are trying to protect.

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