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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
2,252 posts
 
Ralph, if I may be so bold as to call you Ralph, thanks for all of the information you have provided. I think we've run our course here, but I've learned a few things and been reminded of things I learned long ago but forgot. I may be a bit pig headed but I'm not stupid. You haven't convinced me that the advantages outweigh the disadvantages, but at least you've piqued my interest in your products and I would love to hear them. That can't be all bad.

And here is something we can agree on that relates to what Russ says above. One huge weakness in the standard SE scheme is the use of RCA connectors. In a nutshell, they suck, but Russ, the fact that a DIN connector has enough pins that it could be used to carry a balanced signal does not make it a balanced connector. The fact that Naim chose to address this weakness by going with a more robust DIN connector does not mean that they "provides much the same result" as being balanced. The earthing scheme may be improved, but other than that it provides absolutely none of the benefits that Ralph has been pointing out with regards to being balanced. Oh, and yeah, I listened several hours yesterday and enjoyed myself immensely. Thanks for asking :>)
atmasphere's avatar
atmasphere
11,793 posts
 
Hi Sean,

The interface to a speaker really depends on the amp, not the speaker. The reason is that the speaker floats, and if you change the connections to it, all that changes is the phase. OTOH, some amps drive a speaker SE and others are balanced. Ours drive it balanced of course, either speaker terminal is floating (not connected to) ground. Some speakers have balanced topologies in the crossovers and other don't.

With regards to the question about the preamp, I'm not able to answer the question as I don't know any of the particulars. I can tell you this: On older MP-1s we used a vacuum tube regulator and there were two problems with this.
Some people did not put in the tube (did not or would not read the manual), and while the preamp would work this way it certainly would not sound right. The other problem is that the tube would fail and the preamp would continue to run, again in a compromised state. Newer MP-1s have this issue fixed with a semiconductor regulator that is impedance, temperature and short protected (and is an order of magnitude better regulation and smoother impedance). That would be my guess about what was going on.

Herman, I agree that RCA connectors have plenty of weaknesses. RCA developed them for purposes other then audio and we have been making do ever since. I prefer a connection that locks in place somehow (like 1/4" phone plugs; I also appreciate their robustness), but that's just me.

My soapbox: If high end audio as an industry went to 1/4 phone connectors, we could use balanced and single-ended connections intermixed, as 1/4 phone plugs can support either. A lot less screwing around...

Naim, being British, is typical of using DIN connectors, like other Euro manufacturers. Its kind of a tradition- I have an old Echolette (used by musicians) made in Germany in the early 60s) that uses DIN connections. DIN connections can be used about any way you want- balanced, SE either in mono or stereo, or as SE inputs/outputs. BTW, Naim uses balanced circuits as elements in their power amp circuits. Just thought you should know :)

Buscis2, thanks for the comments. I've taught more then one class in the past and the education aspect definately gets away from me. High End Audio being what it is, you can spend *WAY* too much money and wind up having a stereo that essentially sucks. I see no point in that, so if I can be helpful I do give it a try. On these forums, I try to stick to what I know and stay away from those things for which I have no passion.
sean
6,231 posts
 
Ralph: There are points that i'd like to respond to on your comments pertaining to the amp / speaker interphase, but i'm going to refrain from doing so for now. I've got my reasons and it has nothing to do with you, your company or your products. As i've mentioned before, i like many of the design aspects and sonics generated of the Atmasphere amps.

As to DIN connectors, as far as i'm concerned, they are the worst audio related connector on the market. I don't care if the "technologically advanced" aka "perfection oriented" Germans invented them, they make a poor connection, are not rugged, lack reasonable spacing between conductors, increase the potential for crosstalk between channels / circuits, are difficult to assemble if working with anything above hair-fine wire, etc... To keep things in perspective, some of my Quad gear uses them. The only reason that i can see that a company would want to use a connector like this is that it minimizes clutter ( Quad gear is typically very small ) and that it "almost" makes one choose products from the same manufacturer due to connection compatability. This guarantees the manufacturer that the unit will be working with suitable support components ( probably their own ) and increases the potential for more sales of their own gear. Then again, the reverse part of that equation is that they end up losing sales due to lack of universal connections. Either way, i HATE those damn DIN plugs!!! Sean
>
eldartford
4,262 posts
 
Sean...IMHO, We are talking about such low voltage/current level signals that connector contact resistance is of little consequence. The practical advantage of DIN connectors is that they lock in place. RCAs are easily pulled out.

Any time you use a stereo amp in bridged mode your speaker wires are "balanced mode". I have always found bridged mode to be good, (assuming that the amp can handle the load impedance) and I don't understand why some folk don't like it.
atmasphere's avatar
atmasphere
11,793 posts
 
Hi Sean, I'm not a big fan of the DIN plugs either. I was just commenting that they seem to be a sort of British/Euro tradition. Get careless, trip on the cable or step on a connector on the floor and its toast. I had to make up the cable for the Echolette I mentioned- what a pain.

Some people that are neater then me won't have these issues, but come to think of it, 1/4 phone plugs are about the only thing you could step on without hurting it right away.

Further thoughts on the speaker issue... almost any dynamic driver would be considered balanced, but few crossovers are. There are dual VC dynamic drivers out there FWIW. Some planar speakers are balanced too. Seems to me some of the Maggies (later ones), ETs and certain ESLs. In the case of a loudspeaker, the balance issues have much to do with the Electromotive device the speaker employs, sort of the reverse of a balanced pickup (like a phono cartridge). IOW a speaker that is not balanced is really the exception rather then the rule
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