Balanced cables

Aw geez, once again folks here set up straw-men solely for the purpose of setting themselves up so they can nobly slay them before the spectating masses and then take a bow for imaginary accolades of heroic wisdom. Or put more simply, for crying out loud, gimme a break!  Nobody in this thread espoused the view that XLR's are inherently better than RCA's. Anyone who has read the leading audio mags knows that most of the better reviewers only have RCA IC's in their personal collections and if XLR's are the only option on a piece of gear, they borrow some from the manufacturer of the particular piece under review. But, when a component is designed for XLR's only, there is no choice. When a component offers both, setting aside the difference in gain, they sometimes sound different and sometimes they don't. Sometimes one sounds better than the other, sometimes they just sound different. This exact question posed by Stingreen, btw, has been covered here before. The responses are quite predictable. There is the camp that says no, all balanced cables competently made sound the same. There is the "all recording studios use Mogami/Belden and that is all you need" camp. And then there are the rest of us who say, "it all depends". Some of the most widely respected amps ever built don't offer true balanced inputs. Take Lamm gear for instance. There are XLR's on the back of Lamm amps but Vladmir Lamm is very open that they are "psuedo balanced". 

So if a balanced dual mono/stereo preamplifier has both XLR and RCA outputs, and both outputs from XLR or RCA or moving signal from a separate mono channel for left and right, then in essence their both balanced cables doing the same thing. Interconnects are nothing more than ground connectors. As I already pointed out, no one called XLR cables balanced cables for almost forty years until the 80's when dual mono/stereo components were on the rise having the option of XLR or RCA outputs. If XLR cables were invented in the 80's for the sole purpose only to use with high end dual-mono components, then technically it would be a balalanced cable only, not a cable that was given the nickname "balanced" due to its great ground properties which works best with noisy components especially noisy tube amplifiers.

Al addressed this correctly. I do have the feeling though that you did not read my post carefully. XLR connections were in wide use in the 1950s- my Ampex 351-2 tape machine, built in 1957, uses XLRs exclusively.

They were used by the recording and broadcast industries beginning in the 1950s, and their introduction to high end audio was made by me in the late 1980s (we introduced the first balanced line product for high end audio in 1987).

The reason XLRs are used for balanced operation is that the relationship of both the non-inverted and inverted signals with respect to ground is identical. This is important for a proper balanced connection and is something an RCA connector simply can't do.

A very well designed solid state preamp is quiet as a tomb and its redundant to use a 1 meter pair of XLR's since there is no noise to deal with. To create this myth that XLR cables have an effect on the quality and quantity of the music signal is outright fraud. The quality is in the recording itself whether its vinyl or CD and has nothing to do with the wire or the connector. If its a very bad recording its going to sound like crap regardless what cable your using, XLR or RCA. Now if you have a poorly designed preamp with a high level of cross talk and noise than the XLR will help to flush out the noise at the output. Its just wire with a good ground, its not a "mini preamp, a "processor", or a buffer like many in the high end retail continue to perpetuate to make more money.

This paragraph is full of outright falsehoods so I will attempt to set the record straight.

The noise of the preamp is a different thing from the noise that can enter a cable. It does not matter if the cable is 6" or 60 meters. Balanced operation still has a noise advantage with respect to the cable, and the additional advantage of being able to eliminate cable artifact. If you had to pay big dollars for a single-ended cable because that was the one that sounded right, that's the kind of artifact I'm talking about!

Now balanced operation within something like a preamp can also have lower noise but for entirely different reasons. For example, we use differential amplifiers in our preamps; for a given stage of gain, a differential amp can have 6db less noise than its single-ended counterpart. 

Differential amplifiers are in common use in many solid state power amps and many opamps. They are used because they offer lower noise and also greater power supply noise rejection. They can be executed in tubes as well (the first production opamps were made in the 1950s by George Philbrick and were all-tube).

The bottom line is balanced operation is used to reduce or eliminate the sound an interconnect cable might impose in the system, and also to reduce or eliminate noise that might be impinged on the cable by power cords, magnetic fields and the like- these are things single-ended cables cannot do. This is why all recordings since the 1950s employ balanced line connections- its not just so that the cables can be run a long ways, but if you sit and think about it, the fact that the technology prevents the cable from modifying the signal does also imply you can run the cable much longer distances without troubles.  This can be quite advantageous in the home; I keep my amps right by my speakers with short speaker runs, and run the interconnect cables about 30 feet to my preamp which is located at the spot in the room with the least bass (room nadir). In this way I get considerably more definition and less coloration.

Again, you'd think that audiophiles would be all over that!

I knew Robert Fulton as he lived here in town. He was the guy that founded the high end audio cable industry. Back in the late 1970s he had a high end RCA cable, and his Fulton Brown and Fulton Gold speaker cables.

If you run RCAs, the cables to make the connections are the hidden cost of any preamp. If you run balanced, and the equipment supports the balanced standard, the cables are cheap but the sound is better than the best RCAs.

So Ralph, based on your engineering knowledge, why would ARC make those design choices? Can you hazard a guess as to what the most likely reasons would be? My experience tells me that there must be trade-off considerations-at this level of audio, there always are.

You are correct. There are several ways to do balanced operation with tubes. If you want to support the balanced standard though, your options become limited because of the low input impedances the standard requires you to be able to drive, and also there is that issue with ignoring ground as I stated in my first post.

In the old days of tubes, an output transformer was employed. That is how my Ampex recorders (which are single-ended internally) drive balanced lines. When transistors came along, and in particular solid state opamps, it became possible to direct-couple the output. But even with solid state, transformers are still in common use even today.

We developed a third means, which is a direct coupled balanced vacuum tube output, for which we also developed a patent. I'm pretty sure ARC didn't have any interest in infringing the patent, using output transformers or a solid state output, so they used the only means left to them, which was to not support the balanced standard. They knew they had to do something because balanced operation offers too many advantages to ignore!

As a result, you can easily hear differences in balanced cables while using their equipment. This is entirely because the balanced standards are not being observed.

Just wanted to reiterate that if designer lays out his signal path to be more direct to the XLR and the gain is set higher to that output it will always sound better which is the intention, if the opposite is done to the RCA out, it will always sound better as well.

This statement is false.

Balanced and single-ended (RCA) operations are inherently incompatible. So if RCAs are used its not balanced, and if the XLR outputs are used (and the preamp is properly balanced) then the use of the RCA connections will result in a buzz.

IOW its one or the other and never both, unless additional active circuitry is used.

The gain has nothing to do with it whatsoever. That is saying that to make something sound better, you just make it louder.

So Ralph, based on your engineering knowledge, why would ARC make those design choices? Can you hazard a guess as to what the most likely reasons would be? My experience tells me that there must be trade-off considerations-at this level of audio, there always are.

You are correct. There are several ways to do balanced operation with tubes. If you want to support the balanced standard though, your options become limited because of the low input impedances the standard requires you to be able to drive, and also there is that issue with ignoring ground as I stated in my first post.

In the old days of tubes, an output transformer was employed. That is how my Ampex recorders (which are single-ended internally) drive balanced lines. When transistors came along, and in particular solid state opamps, it became possible to direct-couple the output. But even with solid state, transformers are still in common use even today.

We developed a third means, which is a direct coupled balanced vacuum tube output, for which we also developed a patent. I'm pretty sure ARC didn't have any interest in infringing the patent, using output transformers or a solid state output, so they used the only means left to them, which was to not support the balanced standard. They knew they had to do something because balanced operation offers too many advantages to ignore!

As a result, you can easily hear differences in balanced cables while using their equipment. This is entirely because the balanced standards are not being observed.

So if I understand you correctly, unlike Vladmir Lamm's open admission to having psuedo-balanced XLR inputs on his amps, ARC's Ref Series amps, including my Ref 150se is truly balanced, but deviates from the convention most likely for the reasons you stated. I will leave it for another day and discussion as to whether you are correct that as long as the convention for true balanced is observed, all functioning XLR IC's will sound identical. I just know that with my Ref 6 preamp and Ref 150se amp, the choice of XLR makes a profound difference-I tried Mogami Gold, a custom-made Chris Sommovigo AirWave, a Morrow MA-6, a Harmonic Tech, and then Cardas Clear Beyond and each was markedly different. Only the Cardas gave me repeated goose bumps and chills down my neck and only the Cardas made my speakers disappear in my room. I am not touting Cardas as best, only that Cardas was the best I tried in MY system. 

Its probably not the amp that is causing you to hear the cables so much as the preamp. But there is a recent period of ARC amps that had me scratching my head. I'm not sure which models they are. They were out when Kalvin Dahl (with whom I went to school) was still at ARC (about 2-3 years ago). Apparently the amp has a very low CMRR (Common Mode Rejection Ratio) so it only has balanced inputs. Apparently also if you try to run it single-ended the power goes down and the distortion goes up.

I can't think of a good reason for a low CMRR in a differential amplifier (which is what these amps use). You wind up leaving performance on the table (I've been designing differential circuits since the mid 1980s).

If that kind of amp is used with a preamp of fairly high output impedance as per any of the ARC Ref series, the result will be that cable differences will be heard.

That last bit is the part I don't get- why defeat the purpose of balanced line? At that point you might as well run single-ended, as the ability to run long cables is lost as well.

It is things like this which is (IMO) why the single-ended/balanced debate continues! Think about this for a moment- from whom do you most often hear that saw that 'cables don't make a difference'? Usually its someone with an audio engineering background. Well, most of those people work in pro audio, where balanced lines are used, the balanced standard is observed and cables thus really don't make a difference. But in high end audio, for some reason (my guess is the difficulty) the balanced standards have been largely ignored, so this conversation continues...