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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
sean
6,231 posts
 
Herman: A cymbal moves up and down to displace the air. The rate that it displaces air is called the frequency and the volume of air displaced is the loudness or amplitude.

Just as the cymbal is pushed down and displaces air in that direction, the other side of the cymbal swings up and displaces air in the opposite direction. It is an equal and opposing force. If we didn't maintain the equal and opposing force, we wouldn't mantain consistent air pressure. If we don't maintain consistent air pressure, we start to develop a state of vacuum. The greater the vacuum that we develop, the less air that we have to displace. When we don't have air to displace or air to replace what has been displaced, we have total vacuum. If we have total vacuum, we don't have sound. Therefore, sound is generated by moving air in a balanced format.

Our ears work the same way. That's why our ears "pop" as we change altitudes rapidly. The pressure inside our ear is not equal to the pressure outside due to the varying densities of air, creating an imbalance. Once the pressure is fully balanced inside and out, our hearing returns to normal and we no longer have "popping" taking place. Sean
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sogood51
2,157 posts
 
Herman, right or wrong..great thread. Atmasphere, Sean, Buscis2 and Eldartford, great input for future revisit and reading!!

Dave
sean
6,231 posts
 
One thing i'd like to add here. If Ralph wasn't wearing his affiliations on his shirt pocket ( Atma Sphere products ), nobody would have known who he was or why he might have the very strong point of view on the subject that he does. Due to the fact that he designs / manufactures audio gear that is balanced, an intelligent person would realize that he has a vested interest in protecting / promoting those interests. As such, comments made by someone in that position may be viewed in a slightly different light. This is not to attack or belittle the input from Ralph or any other manufacturer / designer / retailer / distributor, etc.. on any given subject, only to demonstrate how important disclosure of affiliations is. There is nothing wrong with sharing an opinion / point of view, regardless of who agrees or disagrees, so long as it is truly honest and not designed to manipulate others for one's own personal gain. Given the mess that we have going on in another thread about this subject, i thought that this was a perfect time to point out why i did / said what i did over there and why this thread hasn't turned into much the same mess. Those with ethics have nothing to fear when contributing to this or any other forum and i hope that they will continue to do so, both on a regular and long term basis.

Now, back to our normal program. Sean
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inpepinnovations1e75
395 posts
 
Sean, it is a common myth that sound is air "moving" balanced or not. Sound is produced by a vibrating object causing the air pressure in its immediate vicinity to vary according to the frequency and amplitude of the vibrating object. This air pressure variation is propagated as a wave of varying pressure - the air does not move - that would be wind!

To use your cymbals as an example, it is not the movement of the cymbal up and down that causes the sound - a single unstruck cymbal moving does not make a sound - but the vibration of the metal cymbal as it is struck that causes the air pressure to vary as described before. In fact, if we move the 2 cymbals towards each other but stop their movement before they touch, we will move a lot of air but there won't be any sound.

The ear responds to varying pressure, not air flow or movement, after all if the air is moving, where is it going in the ear?
sean
6,231 posts
 
Bob: I understand that sound doesn't move air, the air simply "transports" the energy of the sounds created. Most people don't understand that, so i tried to word it in a way that was easier to follow. It is good that you mentioned this though, because my "simple analogy" could be considered "misinformation" if one were to take it word for word. Thanks for the clarification.

"To use your cymbals as an example, it is not the movement of the cymbal up and down that causes the sound - a single unstruck cymbal moving does not make a sound:

This is incorrect. Anything moving is creating sound because that movement imparts energy into the air. Whether or not that energy / sound is of high enough amplitude or at a frequency that we can hear is another matter.

" but the vibration of the metal cymbal as it is struck that causes the air pressure to vary as described before"

This supports my comments above. The only variance between the unstruck yet moving cymbal and the cymbal that was struck is the intensity of the movement generated and the frequency of excitation. Add the resonant and transient ( rise and fall ) characteristics of the cymbal to this movement and you have a specific sonic trait.

"In fact, if we move the 2 cymbals towards each other but stop their movement before they touch, we will move a lot of air but there won't be any sound."

False. There is sound, but it may not be of high enough amplitude or high enough in frequency for us to easily hear. If you doubt this, take a large yet solid lightweight item and move it back and forth in the air making long and slow excursions. You might not hear anything even though air is moving. Moving the item back and forth at a faster rate ( like "fanning" yourself ) will produce sound that is more audible and centered at a higher frequency. Same thing is taking place in both examples, the only variances are amplitude and frequency.

"The ear responds to varying pressure, not air flow or movement, after all if the air is moving, where is it going in the ear?"

Herman and i discussed this somewhat privately via email. Neither of us will argue this point. Sean
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