I assume all digital cables are 75 ohm(?) and from what I’ve read it would be ideal to maintain this value if adaptors are introduced on one or both ends.
In my case I have an Audioquest Carbon between my Core and Mojo. Again, I’m assuming the Carbon is 75 ohm, but I have to add a BNC adaptor at the Core end and a 3.5 Plug at the Mojo end.
Are the extra adaptors likely changing the 75 ohm value? At any rate I may experiment with a cable without the need for adaptors.
Would anyone like to chime in with their experiences?
Coaxial cables if called digital should be 75 ohm because as far as I am aware there is no digital specification using other impedances. As long as 75 ohm it doesn’t need the word ‘digital’ to be suitable, but just needs to be high quality with well made connections preserving true 75 ohm impedance, and the best RF shielding you can get.
Beware of boutique audiophile cables: in reality they may not be any better despite whatever they claim or whatever reviews they might have, so if tempted it makes sense to compare - and preferably blind.
The above is general: when talking about 3.5 mm connections then I don’t think they can be true 75 ohm, so it is a moot point whether a fitted plug is better than using an adapter which otherwise generally are not considered ideal.
I don’t have experience of your exact setup, but I would contact Mark Grant Cables. Mark will build a 75 ohm cable with appropriate connectors (Canare) at each end high quality cable. It will mean you won’t have to use adapters.
However, if what you have sounds great then my recommended setup will not necessarily bring you improvements, but it will look neater and be technically correct.
If he drops by then @Analogmusic is the man who knows how to get the best from a Mojo. I think he uses Vertere cables, but best he he explains.
A Chord Poly may be an alternative, but you need to audition to be sure it did what you wanted and it is more expensive than a Mark Grant Cable.
AFAIK, the only commonly used s/pdif digital coaxial connector that can ensure anywhere near 75ohms is a 75ohm BNC. Use an adaptor though and of course all bets are off thanks to the extra non-BNC connection.
Actually I don’t use Mojo with the coax SPDIF input. I use it with USB and Optical inputs.
but what I would do for sure - is use one of the Chord (cable co.) clearway digital SDIF cables with the Naim Core which was designed for the Chord Mojo.
The issue with not having 75 ohms on both ends is the reflections of the signal which go back and forth and confuse the input receiver on the DAC.
It may or may not be such an audible issue, but Chord cables have designed their Sarum Tuned Aray range as a solution to this issue, and now we are lucky to have this in the clearway range at a decent price point. They specifically added some clever extra stuff in their cables to ensure the reflections are reduced and do not effect the input receiver of the DAC as much.
I find the Google Chromecast audio is a good streamer with my Mojo, has an optical output, and has tidal and spotify native playback, and besides works great with Bubble UPNP… that is how I use the mojo at home and it really sounds musical and rhythmic.
This is not directly relevant to you using a Mojo, but I’ve used various coax cables between Naim streamers and Chord DACs, both with and without adapters. I found the difference between all of them to be very small, including the use of a BNC to RCA adapter. Once I had the hardware sorted, I did buy a cable with the right connectors on both ends rather than using an adapter just for peace of mind. One of the cables I tried was a Naim DC1 which is a lot more expensive than the others, but I rejected it as it was only available in one length that was far longer than I needed and being quite stiff, just looked like a complete mess.
Brands that I’m aware of making a 3.5mm jack to BNC cable include Chord, Flashback and Atlas.
AES/EBU standard requires a cable with 110Ω characteristic impedance.
Coax S/Pdif specifies 75Ω characteristic impedance, but is usually implementd using RCA phono connectors that have non-constant impedance of less than 75Ω (often in the 20-40Ω region). Occasionally 3.5mm jacks are used and I have no idea of the impedance of this connector. Unless coax S/Pdif is through BNC it’s likely that the connector will to some degree compromise the transmission.
Thanks all for responding with your knowledge and experiences with digital cables. The Audioquest Carbon works great in my system, and even with adaptors on both ends I was able to discern its superiority over less costly Audioquests. So I’m thinking I’m doing well even if not 100% “correct”.
Thanks Analog the information on the “reflections” inherent in non 75 ohm cables. Nice to know that Chord have an alternative dealing with the issue.
Yes. The Only way to keep it all 75ohm is BNC at both ends. Least expensive true 75 ohm cable I know of is Black Cat Audio. But as Richard said put any adapters on and it’s no longer 75ohm