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-   -   Balanced Drive sounds better? How?! (http://www.diyaudio.com/forums/headphone-systems/207571-balanced-drive-sounds-better-how.html)

b1o2r3i4s5 26th February 2012 08:50 AM

Balanced Drive sounds better? How?!
 
I recently came across balanced headphone driving (better known as amp bridging) and just don't understand how this will make it sound better.

I understand how Balanced line transmission can cancel out interference induced to the cable using a Differential receiver.
but a headphone with a max cable length of maybe 5 meters?

stratus46 26th February 2012 09:00 AM

Quote:

Originally Posted by b1o2r3i4s5 (Post 2923136)
I recently came across balanced headphone driving (better known as amp bridging) and just don't understand how this will make it sound better.

I understand how Balanced line transmission can cancel out interference induced to the cable using a Differential receiver.
but a headphone with a max cable length of maybe 5 meters?

IMO it won't but it shouldn't make it worse either. You will have to convert your 3 wire system to a 4 wire to use bridge amps. I don't understand why anyone would bother with this.Bridge amps are usually used to increase power (more Voltage) on the cheap. Headphones require so little power this wouldn't be an issue.

G

qusp 26th February 2012 09:14 AM

balanced and bridged are 2 different things; a balanced amp is bridged, but a bridged amp does not have to be balanced. for me its more about continuing a balanced signal path all the way to the end. most (ALL IMO) the top performing dac chips are balanced, it helps performance there with VERY short distances involved and its got nothing to do with power; what makes you think it all of a sudden becomes meaningless when talking about the headphones?

try it, you might like it

crosstalk is lower, some aspects of noise and distortion are lower and for me its most definitely subjectively better also

jcx 26th February 2012 09:16 AM

in principle bridged drive will cause even order distortion cancellation if the the 2 sides match well

some higher Z headphones need more drive V than can be had with common op amps - so doubling your Vswing can be useful for some

but there does seem to be unwarrated high expectations for "balanced" bridge output amps for many headphones

there are very few "true diferential in/out" amplifiers, Gilmore's "dyna-mid", ESL amps - most just use 2 separate amps

qusp 26th February 2012 09:19 AM

agreed its hyped more than it possibly deserves, it doesnt all of a sudden mean its better just because its balanced, but its still my preference

b1o2r3i4s5 26th February 2012 09:28 AM

Quote:

Originally Posted by qusp (Post 2923149)
balanced and bridged are 2 different things; a balanced amp is bridged, but a bridged amp does not have to be balanced. for me its more about continuing a balanced signal path all the way to the end. most (ALL IMO) the top performing dac chips are balanced, it helps performance there with VERY short distances involved and its got nothing to do with power; what makes you think it all of a sudden becomes meaningless when talking about the headphones?

try it, you might like it

crosstalk is lower, some aspects of noise and distortion are lower and for me its most definitely subjectively better also

I see, its so that the 2 channels are completely separated so that signals that may have gotten in the common ground does not affect the output right?

qusp 26th February 2012 10:01 AM

thats one aspect yes, the shared return is avoided (which contains ALL of the return signals, not just some that might have 'made it in', do not think of ground as some place residual signal dribbles into) noise, distortion, crosstalk, any error that is common to both phases of a channel but isnt inverted like the signal is, is deleted to a large extent

ethanolson 27th February 2012 08:45 PM

Doesn't balanced do push/pull and unbalanced do push/no-push on the speaker capsule?

SoNic_real_one 27th February 2012 08:47 PM

No, both do the exact same thing. common return is avoided in more expensive headphones by providing four wires, connected to ground only back to the jack.
Altough, for the mW that travel on those wires is overkill...

regal 3rd March 2012 09:12 AM

Balanced outputs to headphones in theory would have a cancellation of common mode junk, but consider using the amplifier to combine the phases and output unbalanced because obviously a high precision circuit is going to do a better job at that that than a voicecoil pushing a cone that was tuned for unbalanced drive. There is in theory also an advantage with balanced output in that the drivers are floating and not connected to a potentially dirty ground, especially if you are using a high speed sigma-delta DAC chip as a source (note that prior to sigma-delta, dac chips didn't have balanced output). So I can see the merit in Qsup's recommendation to leave balanced all the way to the headphones with a modern setup..

But keep in mind the output impedance comes into play because the headphone load to the amp is halved. In other words if you have 32 ohm headphones in balanced they are actually a 16 ohm load to the balanced output amplifier.

Where balanced output has really helped is with opamp gain stages in headphone amps, they generally top out at 7Vrms max swing before that nasty spike in thd vs Vrms. So balanced out gives you double that swing depending on the buffer's current handling.

So with a modern mid-level level setup with a DAC like the ES9018 and modern amp, its something worth looking at. The digital volume control really helps with a balanced setup because 4 -signal attentuation in analog is troublesome and expensive.

But if you are into classic multi-bit DAC and tube amps balanced becomes more trouble than worth.


So you really need to decide what system you like and what headphones you like before you make the decision to re-wire all your headphones for balanced. You can make a balanced to 1/4" headphone plug adapter to switch between amps, but all this costs money and time.


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