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balanced is inherently flawed

A recent post asking for opinions on balanced vs. single ended got me thinking once again about the inherent flaws in a balanced scheme.

A balanced signal has 2 parts called plus (+) and minus (-) that are equal in voltage but opposite in polarity. Therefore a balanced amp is really 2 single ended amps in one package, one for the + singal and the other for the - signal. So a balanced amp using the same quality parts as a single ended amp will be twice as expensive. Strike one.

That brings us to the "equal but opposite" notion. In order for this to work as planned, all of the + stages and cables connecting them must be exactly equal to all of the - stages all the way through the source, preamp, and power amp. Any deviation from the + stage being the exact mirror image of the - stage will result in an imbalance. Since perfect symmetry cannot be achieved, especially with tubes, distortions are introduced. Strike two.

Some think that balanced has to be better for various reasons that include:

1. If they hook up a balanced device using single ended cables they loose some gain.
2. They think a balanced system can achieve a lower noise floor.
3. They have balanced equipment and it sounds better when they hook it up with balanced cables vs. single ended cables.
4. It's used in recording studios by the pros so it must be better.

These arguments are flawed for the following reasons:

1. More gain does not equal better sound. Of course you need enough gain to drive your speakers to satisfactory levels, but the fact that one connection has higher gain than another has really nothing to do with sound quality.

2. This is the most misunderstood of all. A balanced amp CAN reject noise that is coming in through the interconnects. However, it can do nothing to reject or cancel the random electrical noise that comes from within the devices inside the amp. A balanced amp has no advantage over a single ended one when it comes to the major contributor of noise in the system, that which is generated inside the amp. The rejection of noise from cables relies on the fact that it is generally equal to both the + and - inputs and is therefore cancelled, but since the noise voltages generated by the devices inside the + and - stages in the amp are random and unrelated, they do not cancel and are passed on to the next stage.

Furthermore, since well designed, shielded interconnects of any type are very good at rejecting electrical noise from the outside, balanced has no advantage except in very noisy enviroments or when using very long runs, both of which apply to recording studios, not to typical home systems.

3. Since a truly balanced amp was built from the ground up to operate in a balanced mode, it makes sense that it will sound worse when fed a single ended signal. That doesn't mean that balanced is better, just that that particular amp sounds better when fed a balanced signal.

If you subscribe to the theory that more money can get you better performance, and since a single ended amp has 1/2 as many components as an equivalent balanced amp, it stands to reason that if the designer put as much money and effort into designing a single ended amp, it would sound better.

4. See 2 above.

And this brings us to our last point. ALL sound sources are single ended. Whether from a plucked string, blowing air through a horn, the human voice, or anything else; the resulting increses and decreases in air pressure that we perceive as sound are single ended. There is no "equal but opposite" waves of pressure. This is also true when the signal finally gets to a loudspeaker. There are no "equal but opposite" pressure waves coming from the speaker. It is a single ended device.

In a balanced system these pressure variations are picked up by a microphone and then some where along the line converted to balanced. A phonograph record is encoded single ended as is a digital disc. Your CD player may have a balanced output but the data that is read from the disc is single ended and then converted. In order not to introduce ditortions, this conversion from single ended to balanced has to be done perfectly. And since it can't be, strike three.
herman
atmasphere's avatar
atmasphere
11,960 posts
 
Hi Herman,

Its obvious to me that you're not getting what I am talking about else you would not be responding this way. I'll try it another way, maybe you'll see.

One of the things balanced does for you is it helps get rid of cable problems. That is how come Mercury was able to park their recording truck behind Northrup Hall in Minneapolis in 1958 and then ran their mic cables over 150 feet from the hall to the truck, and got a recording that is still considered state of the art today. If there were the cable problems that audiophiles see routinely today, this would simply not have been possible. Mercury did this in 1958 when no exotic cable industry existed at all. How did they do this? Balanced Line connections.

You can't say that this has no effect on you as an audiophile- Mercury's recordings are legendary. Now, if you could have a cable system in the home that eliminated cable problems, so you could run 30 or 50 feet of cable without any high frequency loss, without any loss of low level detail, for that matter sounded excellent regardless of the cable you used, would you be interested? If you say no, you will not be in agreement with most of the audio community. These are very real benefits of balanced lines, and they have very real benefits for audiophiles who use them in the home.

I used the other industry examples to make a point, which was that these industries benefited from this technology for the same reasons that audiophiles can:

Lower noise
Lower distortion
cable immunity
wider bandwidth

These are very real benefits and are readily audible.

Yes, a light sensor (from a CD pickup) is a balanced device. It has two leads, neither of which has to be tied to ground to work properly. That's how most balanced sources work. How a designer chooses to use the device is a different story, just like a phono cartridge, which is another inherently balanced source. Sure, you can use it SE, most people do, but at the end of the day the cartridge will not care how it terminals are connected, as neither side of the inductor is tied to ground. That's how balanced sources work. If you let both sides of the cartridge float, and just use the tonearm as a shield, along with the shield of the tonearm interconnect, you have a very elegent and simple balanced setup. Nothing to it. Its actually *harder* to run the cartridge SE, as noise, hum and RF interference are harder to get rid of and you have three connections to make instead of two.

I'll revisit the noise thing for a moment. Its possile to build a phono section with less stages of gain then ba single ended phono section, using a differential topology, one that can work directly with low output moving coil and yet be quiet. Now, if you can eliminate a whole stage of gain, you have less distortion, wider bandwidth and greater definition all at once. Audiophiles like that sort of thing. Sounds better. That's a very real benefit, its already in service in the field, and it connot be denied.

It would be nice if this was a case where we could agree to disagree, where this was all opinion. But this is not about opinion, which is why I feel compelled to set the record straight. There's a lot that I don't know, like, for example, anything much about saxopones. Kenny G kinda wrecked that for me. But I have been working with balanced circuitry for the better part of 30 years, and seen repeatedly how much better it performs then single-ended approaches to audio. Not that I'm saying that SE is bad, just that balanced (done right, which is not that hard) is better and *any* audiophile can hear it. I had a girlfriend who was deaf in one ear, and half deaf in the other, and *she* could hear it, so I am confident you can too if it give it a straight shot. You know, just the facts.
herman OP
2,273 posts
 
To imply that the manner of detecting the logic state of the laser sensor in a CD player is in any way, shape, or form related to a discussion about balanced sources is laughable, and even though I may be the largest source of mis-information on this forum, you are embarrassing yourself with this one.

Your information about Mercury recordings in 1958 was also very interesting, too bad it has nothing to do with how the system at my house reproduces that recording.

And it is most definitely about opinion. There is no quantifiable way to determine what sounds better even if you do have a half deaf girlfriend :>) If there was, Julian Hirsch would be an audiophile god.

I have given it a straight shot. I've owned and/or listened to some of the most highly regarded balanced systems out there, I hope to hear yours some day.
herman OP
2,273 posts
 
Lets explore your reasons why audiophiles benefit from balanced designs:

"Lower noise
Lower distortion
cable immunity
wider bandwidth"

If lower noise and distortion are the holy grail that you make them out to be, why are you using tubes when they are inherently noisy? You can achieve even better noise and distortion figures with transistors. We went down the "lower distortion is better" road in the 70's until the end result was a bunch of high powered amplifiers with .00001% distortion that sounded like crap. I won't disagree that tubes can sound very pleasing and I would use them if I had the patience to deal with them, but you have to attribute that pleasing sound to some kind of inherent distortion, which sort of contradicts your lower distortion is better arguement.

If immune to cable differences and "sounded excellent no matter what cable you used", why do I and thousands of others hear significant differences when switching cables?

Wider bandwidth than what? The 100 kHz that your amps do is easily achieved by single ended designs.
atmasphere's avatar
atmasphere
11,960 posts
 
Hi Herman

I see that you do not understand how balanced signals works. That's OK. Here's a short primer:

Any signal source (transducer: either electromechanical, inductive or light) that does not use ground as a reference is a balanced source. What this means is that as long as one of the output leads of the device will work as well as the other, and switching them only means that phase has been reversed, then the device is a balanced source.

Phono cartridges are like this, tape heads are like this, microphones are like this, light sensing pickups are like this. So *IF* you wanted to, you could use the output of a laser pickup in the balanced domain. There are CD drives that do this out in the field and in service; I read about a company doing this over ten years ago! I don't keep up on digital technology as much as analog so I don't know of current (no pun intended) examples. Now the fact that this is the case is probably not really very important, since the analog signal that comes off the light pickup is interpreted as a digital signal fairly close to the pickup itself.

Herman, to say that what happened with Mercury in 1958 has nothing to do with how your system operates is flat wrong. Here's how I know: What does you stereo sound like with nothing playing on it? Hopefully, silence, or very near that. Where does the recording come from that you play? A: The record labels, unless *ALL* the recordings you play are made by you or your friends. IF not, then the effects of balanced line technology are all around you, in every commercial recording you play. Its inescapable. Therefore it is impossible that this has no effect on your stereo, unless you just plain and simple do not play recordings on it.

That we are not talking about opinion is very simple as the benefits of balanced line are one of the few areas of audio that are both audible and quantifiable. There are plenty of ways to 'determine what sounds better', and they can be quantified as long as there is enough experience to detirmine what measurements correllate with the sounds that we hear (poor Julian...).

If this is not obvious from the equipment that you have heard, it might be that that gear has its own weaknesses that have nothing to do with blanced operation. The reason I say this is that the legacy of 45 some odd years of hifi recordings is a rather massive testemony to the success of the technology. A few high-end audio failures are not suficient to be its defeat.

My advice is to listen to balanced gear that is done right, as I am sure you will agree that it is importanat to listen to single-ended gear that is done right for the same reason!

At least we both agree about Mr. Hirsch!
russ_l
95 posts
 
Herman- Sounds like you have a nice system. Do you ever listen to it? And one more time, being that you are a Naim owner, Naim uses DIN connectors "to eliminate earthing problems and improve CMR" (go to their website or give them a call). As you have stated "Naim is not fully balanced", but conceptually the use of balanced (DIN) connectors provides much the same result. Give it up already; as I said above "no one is twisting your arm".
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