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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
herman OP
2,290 posts
 
Thanks for taking the time to more clearly state your case. It was much better than the "it is better because it is better" post you put up earlier.

You seem to miss the big point here.

We are talking about home stereo, nothing else. Not recording studios, not the phone company, nothing but home stereo. I don't care if NASA used balanced circuits to cut down on noise. I'm not going to the moon.

I concede that balanced has advantages in the noise arena, but I'll repeat myself. If my 103 dB speakers are dead quiet with a relatively inexpensive ($1,350) integrated, who cares how much quieter balanced will be?

I concede the point, I just don't see any advantage for my home stereo.

As far as being wrong on every point, you don't seem to understand what it means to be a balanced source. I'll explain. It means you have two signals of equal amplitude but opposite polarity.

There is absolutely no commercial media available today that stores data in a balanced format. The ability to output a balanced signal means that a conversion has to be done somewhere. Even if you use a phono cartridge in a balanced mode, the data on the disc is single ended. Once again, I don't care what they use in a studio, I don't use microphones at my house.

Balanced output from a laser diode? You made that up, right? The sensor reading the reflections from the disc either outputs a high or a low depending on whether or not the laser hits a spot where light is reflected: a high or a low, a one or a zero, a true or a false. The information on the CD is stored in a digital format as data representing a certain amplitude at a certain point in time. The next data point is either, higher, lower, or the same as the data point before it. There is absolutely nothing at all balanced about any of that.

In twenty plus years I have yet to hit a dead spot on a volume control. I'll take my chances.

I see nothing in the information you presented that leads me to believe that balanced will sound better than single ended. Please note I said "sound better," not that everything else being equal it can achieve a lower noise floor.

I know we are beating a dead horse here so I'll let it go.

Good luck selling your inherently flawed balanced stuff :>)
I'll continue to enjoy my inherently flawed single ended.
onhwy61's avatar
onhwy61
5,351 posts
 
If all you had said was that you didn't see any advantages for balanced equipment in your own home system, then who but you would be in a better position than you to make such a statement. However, you grossly extrapolated your position and stated that balanced is inherently flawed. While some of your observations may be valid your conclusion is not particularly logical.
herman OP
2,290 posts
 
Onhwy61, if you only read my last post then I can see where you come to your conclusion, but if you followed from the beginning you will see that one of my main reasons for taking the inherently flawed position has to do with the problem of first taking data that is single ended and creating an inverted copy, and then maintaining equal but opposite signals through the system.

I'll stand by that even though I did get pulled off track a bit with the noise and source issue.
atmasphere's avatar
atmasphere
12,171 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
2,290 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.
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