In light of the possibility that Spectral would roll there own cables for use in there system. I just wish Spectral would allow new customers and old if they elected to; for the option to use BNC connections throughout the audio system; that is for unbalanced connections outputs/inputs on CD players, pre-amps, ampilifers. I believe that Robert Harley on more than one occasion mentioned the superior nature of this termination compared to RCAs. "Though BNC is better than RCA-mechanically, electrically, and sonically-it never caught on". And yet there are XLR connections available, and the system remains inherently balanced. Customers are encouraged to use single ended connections because as some writers on this subject, and on this forum have found out that it just sounds better. Huh! Why not just engineer it to be totally balanced and get the best performance out of the system?
The following, which is dated information has haunted me over the years, I hope Mr. Miller's experiences and insights adds to this tread although it does go off this tread some what. As the above infers I think that Spectral "could and should" offer their customers the option to use BNC connectors on their equipment if its truly deemed an advantage in the ways already mentioned. When your shooting for the best, it should be obtainable, don't you think?
The Real Meaning of BNC, XLR
Editor:
I read with interest Wes Phillips article “Totally Wired” in the Spring of 1996 issue. While I applaud his intent, the utility of the article is marred by serious errors of fact which must be addressed. I hope that you and Mr. Phillips will accept these constructively, as they are intended. I will deliberately avoid any discussion of “six-nines” copper, OFC, litz-wire construction, etc., as positions on these subjects are in my opinion matters of religion rather than science.
Let’s start with the glossary in the sidebar on page 14. BNC is not an abbreviation for “British Naval Connector!” It really means Bayonet N, Compact. The N connector was introduced near the end of WWII for UHF and VHF applications, such as radar sets. It is rugged, waterproof, and can handle a considerable amount of power (at least 1kW at VHF). It’s about an inch in diameter and has a threaded coupling nut.
Two smaller connectors were derived from the N: the TNC and the BNC. Both use the same “guts” as the N, but are considerably smaller (around ½-inch in diameter), as they were designed for smaller cable. The BNC has a bayonet coupling nut (hence the name). The TNC is identical in dimension, but has a threaded coupling nut like the N.
All three connectors are optimized for RF, and the real ones maintain a constant 50 ohm impedance throughout the mated connector pair. Only recently have mechanically-compatible true 75 ohm BNCs become available, because they are required for serial digital video (SMPTE 259M). The BNC has been the standard broadcast/professional video connector for at least 20 years, so it’s unsurprising that products primarily aimed at that market employ it almost exclusively.
The term “bayonet” refers specifically to a turn-to-lock coupling nut like the one on the BNC, which is based on the coupling used to fix a bayonet onto a rifle. It does not refer to the center contact, as Mr. Phillips infers in his comment regarding the F connector. The male F is just a crimp-on ferrule with a threaded coupling nut. It was designed for cable TV and master antenna applications, where a premium is placed on low leakage, low cost, and ease of installation in the field, and is intended to be mated once and left in place for the next 10 or so years. Cable TV drop cable typically has a hard-drawn copper or Copperweld center conductor, so it was felt that a separately-installed center pin would be an unnecessary expense.
F connectors should always be tightened using a wrench, preferably an open-ended box wrench or one of the special types made for the purpose, but never over-torqued. Premium F connectors are available with crimp-on gold-plated center pins. The push-on F connectors on the jumper cables supplied with most VCRs are beneath contempt, and should be trashed.
The RCA connector was never intended for baseband audio, or video, for that matter. It was designed for RF and IF connections within TV receivers, from the input balun to the tuner to the chassis. As such, its nominal impedance should be 75 ohms, not 50, although most don’t maintain a constant impedance at all. Premium quality crimpable RCA connectors have recently been made available. The real problem with the RCA connector is the female center contact [inside the jack], and you’re at the equipment manufacturer’s mercy here. If you have the skill, tear ‘em all out and replace ‘em with BNCs!
The XLR connector: “X-series Lockheed, Rubber,” indeed! The XLR was introduced by Cannon in 1956 as an improvement on their XL connector, which in turn an improvement on the X connector. The X was a friction-retained audio connector, similar to the P connector series but much smaller. The XL added a positive latch or lock (hence the L). The XLR was distinguished by the resilient (thus the R) ribs and mating face on the female connector. There was also a version with phenolic dielectric in the male and female connectors, which was dubbed the XLP. The most common current versions from Switchcraft and Neutrik are closer to the XLP than the XLR, although some types employ spring members to emulate the feel of the resilient ribs.
By the way, the XLR is not the only available connector for AES/EBU digital audio. The Society of Motion Picture and Television Engineers (SMPTE) recently standardized a coaxial interface using BNC connectors. Since BNCs are much cheaper to install reliably than XLRs and since AES/EBU audio is reliably handled by analog video distribution equipment, many broadcasters have opted to use BNCs and coax for it.
The spade lug: The “audiophile-approved way to terminate speaker wire”? Not in my book! The problem is not the lug-to-wire crimp but the binding-post-to-lug connection, which is virtually impossible to torque correctly. A better approach, in my humble opinion, for connecting to the binding posts is the banana plug, but I think the greatest promise is shown by the Neutrik Speakon connector, which is specifically designed for this purpose. Few outside the professional sound community are aware of its existence, however.
If that film of oxidation that forms between loosened connectors only behaved as a capacitor, poor connections wouldn’t sound half as bad as they do. The real problem is that the oxides behave as semiconductors, exhibiting a nonlinear response to applied signals. In English, that means they introduce distortion, and the lower the signal level, the worse the effect.
A final comment about interconnects. No matter the quality of the cable or connectors, an interconnect is only as good as the methods used to assemble it. I’ve been a broadcast engineer for 20 years, and I’ve evaluated, bought, assembled, or installed several hundred thousand cables and connectors in that time. In my experience, there is no better termination technique than a precision, gas-tight crimp. The problem with solder is that there are so many ways for a solder connection to be screwed up, and the spot welds you find in molded cables are often underdone or burned through. Given the proper tools, even a moderately skilled technician can turn out consistent, reliable crimps every time.
My interconnect of choice for unbalanced connections is made of broadcast-grade coax and crimp-on BNCs with gold center pins and tarnish-resistant nickel-plated shells. Even in small quantities these connectors are available for single-digit prices. There are over a million BNC connectors in the TV facility in which I work. Fewer than a hundred fail in any given year, and the vast majority of these are due to abuse. If you’re serious about quality connections, invest $100 or so in a proper set of coax stripper and crimpers, and learn to use them, or buy your cables from someone who does.
William C. Miller
ABC Broadcast Operations &
Engineering
Fellow, SMPTE
This letter to the editor was taken from: Sterophile Guide to Home Theater, Summer, 1996 pages 12-13.
