Balanced cables

Al, I always read your posts with interest. You clearly know far more than I do about technical aspects of electronics. I can not read a schematic and never understood concepts of loading as it pertains to amps or phono cartridges :-). With that spirit in mind, I think I know this; say what you wish about ARC, but their 40 year history of building top-tier preamps is incontrovertible. I am going to venture a guess that while Ralph is most likely correct, there are also drawbacks to designing a preamp that is capable of driving low impedance loads. Even if it were true that with certain preamp designs, the quality or "pickiness" of the XLR choice were minimal, is that attribute a "freebie" without trade-offs? I can't help but think of the relatively high negative feedback employed by ARC in the Ref 150se. It's a buzzword in the industry that "no negative feedback" or "minimal negative feedback" is and of itself a mark of distinction and superior sound. Again, I only know that I am getting hair raising chills on the back of my neck and total immersion in the music with the tonal density I had hoped for and without any perceptible bloat, with a wide and deep soundstage that was not critical on my wish-list, but a happily accepted bonus. As with many hobbies, there are certain buzzwords that tend to predominate as accepted truths, but the reality is that "it all depends". 

Is this the same Stingreen who knows all about VPI gear, turntable set-up, and Quicksilver gear, the same Stingreen who years ago gave me specific advice as to how to upgrade the coupling caps on my ARC VS110? :-)
I was a bit surprised to see that you have expressed your disdain for Cardas cables. My opinion/experience is that as the quality of the electronics goes up and assuming that the design is truly balanced, than yes, there are marked differences among XLR cables. I totally understand the viewpoint of cable-skeptics because the differences are on one hand subtle and yet on the other, they can be huge. One analogy is a photograph that is ever so slightly out of focus vs. the same photo that is. As the quality of the gear increases, the perception of that perfectly in-focus image is better appreciated. I now own an ARC Ref 6 and ARC Ref 150se and I tried a variety of XLR's between the pre and amp and also various speaker cables and with each, I heard vast differences. The Ref 150se doesn't even have single ended inputs. ARC stresses in their manual that the quality of the XLR going into the Ref 150se is critical and they were telling the truth. I ended up with Cardas Clear Beyond XLR and Cardas Clear speaker cables and could not be happier. 
When I first upgraded my electronics, I read all I could about the opposing views on XLR's and saw the posts of those who say that with balanced cables, the differences of various brands are minimal and suggesting that Mogami Gold is all one needs because that is what is used in recording studios. This is one of those things that sounds good on paper but does not fly in reality. I started out with those Mogami Golds and they were the sonic equivalent of that girl that your mom says has a "very nice personality". A $600 pair of Morrow MA-6's were better, but the sound was etched, tone and timbre sounded "off", and my music was coming out of two boxes. A pair of top level Harmonic Tech's on loan from a dealer were very nice but not quite what I wanted. With the Cardas, tone and timbre are spot-on, I get the chills on the back of the neck that I never came close to getting with any of the other wire, my speakers disappear in my room, and everything is in focus. 

Atma-Sphere is Ralph Karsten, http://www.atma-sphere.com/AboutUs

I agree that simply recommending the cable that worked for you is senseless. However, it is very unfortunate that this thread has to once again devolve into the debate as to whether wire is wire. For those that believe that all wire is wire, fine. Maybe with your system, wire is indeed wire, with no perceptible differences and you could put ten listeners in your room and all would compare notes afterward and all agree. And please don't read some intent to malign your system when I say that. It is always possible that in the culprit for Stingreen's perceived harshness with his Vandersteens have nothing to do with cabling and more importantly, can't be successfully addressed with cabling. But one thing is beyond debate and that is this; in some systems and for some people different cables sound markedly different. I say this in the context of IC's and SC's only. Let's leave PC's out of this. Stingreen, I usually read your posts. IIRC, you've been running Are and Vandies for a while now. When did the perceived metallic sound start and what-that you can think of-changed in your system when the metallic sound was first noticed? Absent some change that you purposefully made, it would seem that there are only two possibilities; a change in your electrical grid or a new sensitivity on your part to something that was always there. 

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. 

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 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. 

FWIW, I'm looking at my manual to my Ref 150 SE and it does not include a schematic and instead only has some specs, including that the output polarity is non-inverting with "Balanced input pin 2+ (IEC-268)"
Also interesting to me is this verbiage;
"IMPORTANT
Use the best available speaker wires and interconnects. Audio Research cannot emphasize this enough. As better components and systems are developed, it becomes increasingly important to avoid the limitations of inferior system interconnections"

Al, that makes a lot of sense to me, but both Warren Gehl (of ARC) and Kalvin told me that the amp employed a differential amplifier at its input. But they may have been reading off of the same cue sheet, which may not have been accurate. Although I've known both of them for 40 years, on this point I'm more willing to believe your theory as it is consistent with the amp's behavior. I never had the heart to to tell them that if what they said was true that a lot of performance was being left on the table. But who knows- maybe that will be part of the next iteration.

At any rate, that aspect of the amp's performance is well-known and acknowledged by ARC. So in the case of a balanced interconnect, if noise were able to impinge the cable, the amp would not be very good at rejecting it (in the old days this was often handled by an input transformer, which is usually very good at CMRR). So this would seem to make the characteristics of the cable more audible. For such an amplifier, I would recommend a cable that is double shielded.

At the risk of coming across as overly defensive (I own and love ARC gear), this sounds just a bit too conjectural/speculative. Warren Gehl to my knowledge does some very limited design work for ARC and is key in QC by reportedly listening to every piece of gear hooked up to his reference system of a Ref 6 and Ref 150se and some old, large Magnepans before the piece leaves the factory. It was, however, Ward Fiebiger who took over the reigns from Bill Johnson in the actual engineering/circuit layouts of ARC's top-level gear including the Ref series of preamps and amps. Now does that make a difference? Probably not. Surely Warren knows enough to answer the question being posed here. I actually tried to ask ARC the very same question, more or less. Guess what they said in response to my email? That I should contact my dealer! Very nice, huh? 

The Cable Company in Ohio has complete charts of those mathematical values from each high end company for their amps and preamps. If you go into a broadcasting-recording supply house and buy inexpensive cable that matches the value numbers of those components you will be blown away at the performance of your gear."

I didn't want to say anything at the time, but this is so wrong in so many ways. TheCableCo. is not in Ohio, not that it matters much, but this falsehood sets the tone for what follows. I can only hazard a guess that the "values" he mentions pertains to output impedance and input impedance but those "values" have nothing to do with matching cables to components. People say all kinds of weird things on the internet and it is best to just smile and ignore. I have just broken from that wisdom.