Why are all these headphones called "Balanced"??
Oct 26, 2009 at 10:59 PM Thread Starter Post #1 of 14

jsplice

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From my understanding, a "balanced" connection typically exists between two powered components, in which each channel has a total of 3 pins/wires: one ground, two hots. One hot carries the signal, and the other hot carries an inverted signal of the first one, which somehow provides the ability to cancel all supposed noise.

When I see all this talk about "balanced" headphones, I don't understand how simply having a ground and a hot to each channel of a set of headphones is "balanced". This is simply how all normal loud speakers are wired (with the exception of bi-wiring). Is "balanced" a term that caught on simply because XLR connectors were chosen to provide this method of headphone connection?
 
Oct 26, 2009 at 11:21 PM Post #4 of 14

Bones13

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I agree with your concerns jsplice, and have wondered the same. The "balanced" cable referenced in the above link describes a shielded pair of wires. Many of the "balanced" headphone wiring here clearly does not have the shielding or third connector, much less a positive/negative pair with ground as third wire and shielding drained to the chassis.

I do think that by not having a common ground wire for headphones, and having a separate hot/ground for each driver does provide for some sound improvement, and is therefore sought after. Many of the "balanced" amplifiers is a "dual mono" setup with each stereo channel being on a different circuit board out to a separate hot/ground out to the headphones.

I am sure that others probably can explain it better.

I am in the process of going balanced myself, so I guess I will find out for myself.
 
Oct 26, 2009 at 11:34 PM Post #5 of 14

jsplice

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Those are some good points. After reading the link above, it makes sense how two active audio components can measure voltage difference between two signals (one signal being the inverted signal of the other), but in headphones, there are no active internal parts continuously measuring voltage differences.

I've also seen some people on here suggest that you won't notice any difference when you go balanced between your amp and source unless you also go "balanced" with your headphones. I think this may only be because removing the common ground between both channels in a headphone cable is more important, which makes other changes more noticeable. In fact, I think if you were to just remove that common ground even WITHOUT a balanced connection between amp and source, you'd still notice a large difference. But as it stands, the only headphone amps the offer "balanced" headphone outs are those that also have balance inputs (as far as I've noticed).
 
Oct 26, 2009 at 11:35 PM Post #6 of 14

barleyguy

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Essentially, balanced cabling gets rid of the common ground between left and right, which can be a source of noise and crosstalk. A balanced amp also gets rid of the common ground, and amplifies all 4 poles of the signal separately.

Here's a link to a great explanation by 6 moons:

6moons audio reviews: Balanced headphones - Part One


Quote:

Originally Posted by jsplice /img/forum/go_quote.gif
Those are some good points. After reading the link above, it makes sense how two active audio components can measure voltage difference between two signals (one signal being the inverted signal of the other), but in headphones, there are no active internal parts continuously measuring voltage differences.

I've also seen some people on here suggest that you won't notice any difference when you go balanced between your amp and source unless you also go "balanced" with your headphones. I think this may only be because removing the common ground between both channels in a headphone cable is more important, which makes other changes more noticeable. In fact, I think if you were to just remove that common ground even WITHOUT a balanced connection between amp and source, you'd still notice a large difference. But as it stands, the only headphone amps the offer "balanced" headphone outs are those that also have balance inputs (as far as I've noticed).



You don't need to "measure" the voltage difference between two signals in order to have a balanced connection between two pieces of equipment. You simply invert the signal, send it across the wire, and invert it back. When you add signal that's been inverted twice to the original, the original signal is doubled, but the noise that was picked up in between is canceled out, because -1 plus 1 equals zero. Pretty simple really.

But that is a different kind of balancing than headphones use. The point of balancing headphones is to get rid of the coupling between the left channel and the right channel.
 
Oct 26, 2009 at 11:56 PM Post #7 of 14

jsplice

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Quote:

Originally Posted by barleyguy /img/forum/go_quote.gif
But that is a different kind of balancing than headphones use. The point of balancing headphones is to get rid of the coupling between the left channel and the right channel.


I guess that's kind of the point that I was making. I think the term "balanced" has been used too liberally lately. I'm still not understanding how removing a common ground wire is "balancing" an audio signal. I suppose if you look hard enough at it, you COULD call that "balanced" because now each channel has its own ground. But this is not "balanced" in the traditional sense of the word.
 
Oct 27, 2009 at 12:50 AM Post #8 of 14

tot

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Quote:

Originally Posted by jsplice /img/forum/go_quote.gif
I'm still not understanding how removing a common ground wire is "balancing" an audio signal. I suppose if you look hard enough at it, you COULD call that "balanced" because now each channel has its own ground. But this is not "balanced" in the traditional sense of the word.


As far as I know the both input signals are amplified separately and passed to the headphones — there is no ground going to the headphones.

Since you need four amplifiers to drive the headphones, balances amplifiers are more expensive that their unbalanced versions.
 
Oct 27, 2009 at 2:00 AM Post #9 of 14

Steve Eddy

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Quote:

Originally Posted by jsplice /img/forum/go_quote.gif
I guess that's kind of the point that I was making. I think the term "balanced" has been used too liberally lately.


I agree.

"Balanced," most everywhere else, refers to a balance of impedances, which is required in balanced interfaces for the best common-mode rejection performance.

But because common-mode rejection isn't any sort of benefit touted by the "balanced" headphone movement, I really don't see much point in using the term "balanced."

Quote:

I'm still not understanding how removing a common ground wire is "balancing" an audio signal.


It isn't necessarily.

Quote:

I suppose if you look hard enough at it, you COULD call that "balanced" because now each channel has its own ground. But this is not "balanced" in the traditional sense of the word.


Nope.

I think "bridged" is a better term for headphone outputs. "Balanced" is fine for balanced inputs, provided they're differential inputs and not just made up of two separate amplifier channels which provide absolutely no common-mode rejection.

se

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Oct 27, 2009 at 2:04 AM Post #10 of 14

Steve Eddy

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Quote:

Originally Posted by tot /img/forum/go_quote.gif
As far as I know the both input signals are amplified separately and passed to the headphones — there is no ground going to the headphones.


That should be called "bridged."

Technically while it does offer equal impedances with respect to ground, it doesn't offer any common-mode rejection which is the raison d'etre of balanced interfaces and that term should be reserved for such things.

Quote:

Since you need four amplifiers to drive the headphones, balances amplifiers are more expensive that their unbalanced versions.


And "bridged" would be a more appropriate term for that.

Though you don't really need four amplifiers to drive the headphones "balanced." You could use two unbalanced channels and drive the headphones through output transformers.

se

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Oct 27, 2009 at 4:06 AM Post #11 of 14

Zaubertuba

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Quote:

Originally Posted by Koyaan I. Sqatsi /img/forum/go_quote.gif
...And "bridged" would be a more appropriate term for that...


I realize this is to an extent just semantics, but wouldn't we be better off calling a four-board amp that's passing a +/- phase to each driver "differential?"
 
Oct 27, 2009 at 4:26 AM Post #12 of 14

Steve Eddy

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Quote:

Originally Posted by Zaubertuba /img/forum/go_quote.gif
I realize this is to an extent just semantics, but wouldn't we be better off calling a four-board amp that's passing a +/- phase to each driver "differential?"


Not really, no. A four board amp isn't differential.

To be differential would mean it only passes the difference (hence differential) between its inputs. Which further means that it wouldn't pass anything that's common mode, i.e. (+1) - (-1) = 0.

But a four board amp will not only pass anything that's common mode, it will amplify it.

A four board amp should be called "bridged."

se

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Oct 27, 2009 at 4:30 AM Post #13 of 14
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Like the 3-pin vs. 4-pin headphone issue, someone needs to chat with HeadRoom about these things, as they are the ones that started the whole "balanced headphones" deal.

However, ultimately it would be simpler just to accept that a balanced signal and balanced headphones refer to different balances, because either way you're going to have to educate people as to what they mean. Whether they use the same term or not wont change that.
 
Oct 27, 2009 at 4:40 AM Post #14 of 14

El_Doug

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This is an argument over nothing more than a naming convention developed by headroom

Though the terms "balanced" and "single-ended" are improperly used with regard to headphones, I do not think anyone is mislead by this terminology. Further, when these terms are used, everyone knows what we are talking about.

If I could go back in time, I would have headroom develop a 4-pin XLR system, and they would refer to it as bridged. Alas, I am short on cash, and cannot afford a flux capacitor
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