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What exactly are the technical benefits of driving headphones in balanced operation? - Page 2

post #16 of 68
3/2/05 at 8:23pm
Quote:
Originally Posted by wali
The Cardas balanced cable for HD650 uses two XLR connectors but on the driver end it uses the regular unbalanced Sennheiser plugs... Now you don't need to be an EE to understand that you can't freaking transmit a 'balanced' signal using 'two' connector jacks.

All the talk of noise canceling and other stuff is useless here because Sennheiser HD650 has only an unbalanced input (show me one headphone with balanced inputs).

End of discussion for those who believe in common sense.
Why? each driver has a + and - terminal to connect to both the signal and its inverse. What else is needed for balanced operation?
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post #17 of 68
3/2/05 at 8:28pm
Quote:
Originally Posted by mulveling
Well, we're measuring the difference in voltage between the postive and negative ends of the voice coil - which is why I decided to use subtraction, lol
I agree. It you put -2V on the negative terminal, and +2V on the positive the potential difference (voltage) is 4V.
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post #18 of 68
3/2/05 at 8:39pm
Quote:
Originally Posted by mulveling
Why? each driver has a + and - terminal to connect to both the signal and its inverse. What else is needed for balanced operation?
Exactly.
BTW, even the cheapest speaker is driven in balanced mode.
The usual unbalanced operation of cans doesn't make much sense except of a smaller plug.This plug causes a short every time you plug it in.
Weird.
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post #19 of 68
3/2/05 at 8:41pm
Thread Starter 
Maybe this helps
Quote:
Originally Posted by dip16amp
Headphones connected to a balanced amp do interpret both inverting and noninverting signals. This is what gives it twice the voltage swing and twice the slew rate.
Dual mono has separate discrete grounds, but is still operated unbalanced with only a single amplifier per channel.
Both have the a four wire connection to the headphones, but one indicates operation as balanced and the other is unbalanced.
On the nature of the HD 600:
Quote:
Originally Posted by gerG
btw, my HD600s were already "dual mono" in that they have a separate ground on each side. My brand new 600s had a bad mini-plug (I hate mini-plugs!) so I clipped it off and added a 1/4" plug. Each of those 2 sides carry a + and a -, and the R & L can be split apart.
And then there's also the first quote by Kevin Gilmore in my post above. Better would be an amp builder/designer stepping into this thread.
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post #20 of 68
3/2/05 at 10:38pm
Quote:
Originally Posted by rodbac
From my reading, a "balanced" connection is one in which the same signal is sent over two wires but with opposite polarities (with the knowledge that the two wires will be equally affected by whatever noise is introduced (RFI or EMI/inductive)).

The receiving device (your phones in this case) then must have the circuitry to read the difference between the two signals, eliminating the noise.

So I think taylor and wali are largely correct (it may effectively double the amplitude of the signal- not sure), save for the fact that the headphones (AFAIK) have no idea how to read any difference between the two, making a "balanced cable" useless.

Any EEs here confirm or correct that?
afaik (everything I saw about electronics is afaik, I'm not an EE) there are two kinds of balanced.
First is the balanced signal, where it eliminates RFI and EMI. I really have no idea how this works.
Second is balanced (push-pull) on the transducer itself. This does not need special circuitry, just a pair of amps.
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post #21 of 68
3/2/05 at 11:22pm
Quote:
Originally Posted by mulveling
Why? each driver has a + and - terminal to connect to both the signal and its inverse. What else is needed for balanced operation?
What did you do with the ground line?
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post #22 of 68
3/2/05 at 11:32pm
Quote:
Originally Posted by wali
What did you do with the ground line?
Don't need it. You've got a virtual ground halfway between the positive and inverse signals. Plus a voice coil's only got 2 terminals, where would a third go?
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post #23 of 68
3/2/05 at 11:48pm
Quote:
Originally Posted by mulveling
Don't need it. You've got a virtual ground halfway between the positive and inverse signals. Plus a voice coil's only got 2 terminals, where would a third go?
An audio cable is only balanced when there are two signal lines with opposite polarities and a ground line -- that is connected to an input source with circuits that performs the noise reduction function.

Any other type of cable configuration which does not comply with above mentioned parameters is not a "balanced" cable.
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post #24 of 68
3/2/05 at 11:54pm
.
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post #25 of 68
3/3/05 at 12:07am
Quote:
Originally Posted by wali
An audio cable is only balanced when there are two signal lines with opposite polarities and a ground line -- that is connected to an input source with circuits that performs the noise reduction function.

Any other type of cable configuration which does not comply with above mentioned parameters is not a "balanced" cable.
I don't get the "circuits that performs the noise reduction function" part. Unless by extra circuits you mean the 2nd stereo amplifier within a balanced amp. Once you have a signal and its inverse you should get the noise rejection for free, right? If not, can you explain or describe the nature of these circuits?
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post #26 of 68
3/3/05 at 12:13am
Quote:
Originally Posted by ayt999
okay, so a three-pin XLR cable that is plugged into a "balanced" headphone amp such as the BlockHead or Balanced Reference is technically not a "balanced" cable anymore since the amp doesn't actively perform noise reduction on it but rather just amplifies both the positive and negative signals and outputs that?
Balanced ICs between two compatible devices (both use balanced circuits) is fine. However balanced headphone output has no "balancing function", since there are no headphones in the world with balanced inputs the XLR cable is connected to an amp but the other end is connected to a two plug headphone jack (in case of sennheiser HD650). So there are no practical reasons for balanced output in a headphone amp when there are no balanced headphones!
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post #27 of 68
3/3/05 at 12:17am
Quote:
Originally Posted by wali
Balanced ICs between two compatible devices (both use balanced circuits) is fine. However balanced headphone output has no "balancing function", since there are no headphones in the world with balanced inputs the XLR cable is connected to an amp but the other end is connected to a two plug headphone jack (in case of sennheiser HD650). So there are no practical reasons for balanced output in a headphone amp when there are no balanced headphones!
Well I'm not the right person to prove it, but I'm pretty sure you're completely wrong on this, lol
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post #28 of 68
3/3/05 at 12:25am
Quote:
Originally Posted by mulveling
I don't get the "circuits that performs the noise reduction function" part.
The main reason for balanced audio cables are noise reduction that can happen in long runs of low impedance cables -- which is very important in recordings and whenever long runs of audio cable is needed.

The noise induced in the cable is equal in both cable lines, and it can be easily rejected by using a differential amplifier with balanced circuts.

Apart from that, there are no other aspects to balanced cables... most audiophiles don't like to use balanced source and amp because it adds more circuits to the signal path and for short runs it has no particular use... Now you can see that why balanced cables are mainly used in pro audio.

Quote:
Well I'm not the right person to prove it, but I'm pretty sure you're completely wrong on this.
Good, now you have to do some research and findout for yourself.
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post #29 of 68
3/3/05 at 1:12am
.
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post #30 of 68
3/3/05 at 6:53am
I think many many people confuse dual mono with balanced operation.

Where's the Rickmonster laying his usual smack down on the technospeak?

-Ed
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