Why so few devices with BNC's??

Completely agree!

Side note … and absolutely nothing inherently wrong with well implemented BNC connection interface when special attention is addressed by designer. My last preferred choice in the chain reaching the DAC.

Edit … I want BNC on my TV! ;-) 

BNCs are much more expensive than RCAs. RCAs were designed for an audio signal and the BNCs are usually used for RF signals, although there is some crossover.  

DAVE.

@russ69  Uh....  yes, we know that.  A few bucks (maybe) vs a few cents.  And yet the Anthem STR preamp (>$4000), NAD M33 (~$6000) and McIntosh C49 ($5500) and have RCA's.  This is "premium" gear using a demonstrably inferior implementation of the spdif protocol.  To get BNC on McIntosh you have to get the $8000 D1100.  There are countless other examples.  Yet few "audiophiles" really seem to care.  Despite that people debate over about premium coaxial cables with RCA terminations along with all manner of other unmeasurable unicorn juice like fancy power cables, elevating speaker cables off the floor, power condtioners, etc etc. 

And in this case one might make the technical argument that the mismatch doesn't become significant until the signal frequency is in the RF, so not audible.  Well, maybe.  Yet how many people here obsess over the sonic differences between 24/96 and 24/192 or whatever?  God save us.

@russ69  Uh....  yes, we know that.  A few bucks (maybe) vs a few cents. 

If it ain't broke, don't fix it. The RCA's only weakness is long cable runs, the XLR solved that issue and is a standard at this point. The BNC offers nothing in the way of improved sonics.

@russ69 If it ain’t broke, don’t fix it. The RCA’s only weakness is long cable runs, the XLR solved that issue and is a standard at this point. The BNC offers nothing in the way of improved sonics.

Is BNC genuinely better sounding in audio components than well implemented RCA? I have to believe if manufacturers truly felt BNC was superior sonically it would be used in place of RCA on a regular basis. Some of the absolutely best sounding audio components are utilizing RCA connection.

Charles.

If AES/EBU is available why offer BNC?

BNC works good in high vibration environments, like aircraft. The locking feature is not needed for home audio.

BNC stands for British Normal Connector…you want BNCs?  Buy British, like Naim, Chord, etc. 

I asked the same question when I was doing a DAC loop and was looking for a cable and there were so few to choose from. All I got was it was old technology.

Hmm, I thought BNC stood for Bayonet Nut Coupler.

RCA connectors have been there since the beginning of audio time. They work for me, and as far as digital they work great also. They certainly are better than toslink with digital. I haven’t felt the need to make this an issue yet.

"The connector was named the BNC (for Bayonet Neill–Concelman) after its bayonet mount locking mechanism and its inventors, Paul Neill and Carl Concelman. Neill worked at Bell Labs and also invented the N connector; Concelman worked at Amphenol and also invented the C connector"

Invented in the 40's.....

@hypoman you are correct 

Believing what you’ve been told…not a solid strategy!

@Russ69:

The RCA’s only weakness is long cable runs, the XLR solved that issue and is a standard at this point. The BNC offers nothing in the way of improved sonics.

This thread is about digital connections! So XLR is not the standard. BNC allows the manufacturer to make digital connections that are "true 75 ohm" instead of "pretend 75 ohm RCA" which improves sonics.

For non-digital connections, RCA is usually there due to price and compatibility, not sonics or reliability. Not surprising that RCA is an inferior connector. It has been around for almost a century!

It’s "Bayonet Neill–Concelman". There’s also the threaded version TNC. Paul Neill also invented the "N" connector and Carl Concelman invented the type "C" connector. The type C resembles an oversized BNC.

BNC connectors are available in 50-ohm and 75-ohm types with the 50-ohm being much more common. They’re physically interchangeable without damage, the primary difference being the lack of an inner plastic ring on the 75-ohm version.

This thread is about digital connections! 

Sorry I didn't notice that until now. The answer is the same though, audio manufacturers are comfortable with RCA connectors and they cost less and do the job. 

A RCA connector is not a particularly good analog connector, even though it can be made at many price points. It is not a digital connector. The impedance of a cable, and its associated connector is determined almost solely by the diameters and spacing of conductors. The materials, and even the permeability of dielectrics is a minor influence. The physical size of the RCA connector is such that it cannot be made to be 75 ohms, no matter how much money you throw at it. When used as a digital connector it will cause a singularity in the flow and a reflection. This is why you see so much written about a RCA digital cable needing to be a certain length. I am not aware of length being a problem for AES/EBU and true 75 ohm cables and connectors. In my experience, for cables meeting design norms, shorter was a little better, and these cables do not need to be expensive. (This does not preclude that golden eared listeners may prefer more expensive cables.)

It is lamentable that bnc is not the defacto norm for 75 ohm digital cables as a true 75 ohm cable can be built with a bnc cable. 
 

Years back on my first outboard DAC I asked the manufacturer if they could use a BNC connector in place of the RCA s/pdif input. They  were happy to oblige. 

For Muse electronics, designed by Dennis Halverson, all digital and video connectors were BNC.

BNC is an acronym for British Nut Connector.  It is most often encountered in measurement equipment and some older hi-fi gear from the likes of Dayton-Wright in Canada.  With the well entrenched RCA Connector it is difficult to usurp.

It is dependable connector that has the advantage of making the ground prior to the positive connection.

"BNC is an acronym for British Nut Connector"

Incorrect.  The acronym is for Bayonet Neill–Concelman.  

Incorrect.  The acronym is for Bayonet Neill–Concelman. 

indeed...

https://en.wikipedia.org/wiki/BNC_connector#:~:text=The%20connector%20was%20named%20the,Paul%20Neill%20and%20Carl%20Concelman.

My Naim amps had BNC and DIN connectors.

A real pain in the arse they were too.

@charles1dad

Some of the absolutely best sounding audio components are utilizing RCA connection.

Agreed, but only 100%.

When Naim changed over to BNC's in the late eighties we used to call the Bloody Nasty Connectors. Nothing against BNC per se, but putting them on the phono section of Naim's preamps at the time when most Naim customers had Linn Sondeks with RCA tonearm cables was just sheer perversity!

@yoyoyaya

When later questioned on that decision, enigmatic Naim boss Julian Vereker would just say, we do it because we think it sounds better like that.

Naim were once an iconoclastic company, but in this particular case they took it too far.

After I eventually ditched the BNC/RCA adapters and got my Linn tonearm cable terminated with BNCs I was just a little disappointed to find that the amount of improvement in the sound equalled an absolute zero.

As Shakespeare might have said, it was all a much ado about nothing.

Thank you Julian, thank you Naim.

@cd318 - yes, it made zero improvement. However it did further enhance the cause of making Naim gear a closed ecosystem where the easiest thing for customers to do was trade up rather than out.

I did like the calendars they used to produce in the eighties though - sorry I didn't catch your Naim etc.!

RCA connectors are infamous for impedance "bumps" in the signal chain in RF applications.  Since they are not 75-ohm, they can set up signal reflections along the transmission line.  Those reflections become a standing wave and that can interfere with the wanted signal.  BNC, TNC, N, C, etc. are constant-impedance connectors, when properly selected and installed.  Not just any BNC will do, as there are both 50-ohm and 75-ohm BNC connectors.

I purchased a Chord MScaler to use with my current and future DACs, but Chord’s BNC connection is a pain as many DACs do not support.  If I get a custom cable with BNC only on one end, selling it later may be impossible.

@cd318 

After I eventually ditched  the BNC/RCA adapters and got my Linn tonearm cable terminated with BNCs I was just a little disappointed to find that the amount of improvement in the sound equalled an absolute zero.

As Shakespeare might have said, it was all a much ado about nothing

This does not surprise me. Many listeners have enjoyed genuinely superb sound quality with audio /digital components utilizing RCA connection. As with all audio matters, it comes down to the level/quality of the implementation.  Sonic performance is the real life arbiter.

Charles

Cost of BNC is mentioned as an issue. For audiophile equipment would not BNC be the lowest cost for digital? An inexpensive commercial grade BNC connector will be better than the most expensive RCA and the same would be true for the cable. All the discussions about SPDIF cables seem to center around fixing issues that would be caused mainly by the RCA?

in my system i mostly use BNC’s for my interconnects.

but it’s not that simple.

i use the darTZeel ’zeel’ BNC 50 ohm interface between my preamp and amps, and between my tape repro and my preamp. then i use RCA’s between my phono pre and preamp, and XLR’s between my dac and preamp. 2 of my sources do not have the proper interface designed into them so i can’t use the ’zeel’ 50 ohm with them.

the ’zeel’ BNC 50 ohm interface is superior to either RCA or XLR. part of it is the robustness of the BNC connection itself with it’s positive secure mechanical lock, but mostly it’s precise impedance matching between components which greatly reduce signal corruption. RCA and XLR will cause echo’s in the signal.

Herve Deletraz of darTZeel uses the ’zeel’ interface for all darTZeel products. there are a few other products out there, such as CH Precision (one of the owners of CH are actually family with Herve) that also include the 50 ohm BNC connections in their products.

properly executed, the 50 ohm BNC interface will sound the same up to .5 kilometer.

IMO there's no sense in even talking about digital coax using RCA's.  It's simply a flawed implementation.  People can argue about whether it's significant or not, but it's flawed regardless.  With proper BNC's it's no longer an issue.  Then the subjectivists can simply debate the merits of 70 ohm cables. 

I've taken the approach of simply not using gear with RCA's in my "serious" setup.  If the manufacturer can't be bothered to go to the trouble of having a BNC connector then I can't be bothered to buy their stuff (same goes for AES/SBU ro the absence thereof).  There have been a couple exceptions though, where I've gone to the trouble of retrofitting BNC sockets.  I did that on my Cambridge CD transport and some other gear in the past. 

Interestingly there IS a fair amount of gear with BNC's, and it seems to generally be such "boutique" suppliers as Lumin, higher end Schiit stuff, Bryston and numerous others.  Mark Levinson or the Japanese?  Not so much. 

I think the RCA and BNC thing was a bigger deal 10-20 years ago. My understanding and I have not done the math is the slow edges of SPDIF make impedance matching not as critical. With the interfaces and DACs today most of them should shrug off a lot of jitter. Our speakers are pretty immune unless things get really bad.

Does Dartzeel use 50 ohm for analog too? I just read something about that on 6moons and seems they do. It was supposed to be a technical dissertation. I think someone nose grew a few feet when they wrote it. It started with a flawed premise than used flawed examples to make a case. Not good. Not good at all. We don’t normally send audio 0.5km but 0.1km is not unusual with balanced differential AES. With any single ended, the ground loop from the distance will be too noisy.

@thespeakerdude

darTZeel only makes analog products except for one integrated amp with a dac in it. the ’zeel’ 50 ohm interface is strictly analog only.

Herve Deletraz of darTZeel wrote an article published in the Sept 2001 issue of Stereophile about Impedance Matching in audio. it’s quite technical. but if you doubt the logic of the 50 ohm BNC advantage for analog interconnects, then you should have the tech knowledge to follow it. it’s serious.

https://www.townshendaudio.com/PDF/Impedance_matching%20deletraz%20paper.pdf

he wrote that article before he launched his audio company where he applied the principles mentioned and included the ’zeel’ BNC 50 ohm interface in all his products.

i have owned darTZeel amps and preamps since 2005 and always used ’zeel’ 50 ohm interconnects. compared them many times to conventional interconnects and always preferred the ’zeel’.

you have a right to your opinions, but there is real science behind the 'zeel'.

@mikelavigne ,

I am not an EE, but I work around them every day, and I have a physics background so I get the concepts. Turns out the 6moons article was excerpts of the one you linked. I don't feel a need to change my past statement, a flawed premise followed by flawed examples. Been around professional audio speakers technically a long time. This "idea" of impedance matching for analog in audio has been around since the 1990s from Goertz. He even patented it: https://patents.google.com/patent/US5393933 for speaker cables.  It keeps rearing it's head every once in a while, gets shot down because it does not work, and then it goes away till it comes back again. With speaker cables, these low impedance cables created problems without solving any, they caused some amps to blow up. It's bad science or marketing.

Maybe one of the EE's out there has a better graph or can make one. I tried to Google a good graph, but didn't have much luck finding one. Not sure this is a 50 ohm or 75 ohm cable, but does not matter, the principle is the same. That number does not work for the frequencies we hear.

I use a high end Marantz CD/SACD player and a dCS Bartok connected by a 75 ohm Shunyata BNC cable.  While the Marantz has a nice on board CD DAC, using its digital BNC output to the Bartok for CDs just sounds better.  The Marantz does an excellent job with its on-board SACD DAC however, a strength of Marantz engineering.