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Old December 9th, 2004, 06:06 PM   #1
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Whats the difference?

Hey There. This is going to sound very pathetic asking a group of professionals, but im somewhat new to this DV Game. What is the difference between balanced and unbalanced audio? Which is generally better \\ most common. Thanks!
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Old December 9th, 2004, 07:21 PM   #2
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OK, here goes. It ain't brain surgery. It's more like plumbing.

Balanced or unbalanced, the audio needs at least two conductors. Why, 'cause it's an alternating current shuttling back and forth almost at the speed of light. (In an oversimplified way, not unlike a standard light fixture. You know, the plug on the end of a lamp cord has two prongs, sometimes three.) The two conductors allow the current to alternate back and forth.

Balanced is better. Balanced means audio is carried on two conductors and they are wrapped by a third conductor called a shield. The shield keeps extraneous noise from getting into your precious audio.

Unbalanced audio runs on two conductors. Unbalanced cable is normally one central conductor wrapped by a shield. The audio on an unbalanced cable is conducted on the central conductor AND THE SHIELD!! Hanging out there makes you wonder why they even bother to call it a shield. That means the audio is much more prone to interference because it doesn't have a shield to surround and protect the audio.

Having one less conductor makes the unbalanced audio;

1. Lower in level. (Trust me on this or it'll take another page.)
2. More prone to interference

So balanced audio is always preferable. Questions?

There will be a quiz!!

Regards,

Ty Ford
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Old December 9th, 2004, 08:03 PM   #3
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Haha thanks Ty, I owe you big ;)
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Old December 9th, 2004, 11:29 PM   #4
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Besides having a real shield, balanced cables have the ability to cancel any noise that reaches the inner conductors.

The audio signal voltage in one conductor at any instant is the mirror image of the other--equal in magnitude but opposite in polarity. Hence, "balanced." The signal is the _difference_ in voltage between them. Any electromagnetic interference that gets to them tends to produce a voltage spike of the same polarity in both conductors, so the difference between them doesn't change.

This is especially important for longer runs of cable, which can act like antennae for electrical noise in the venue.
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Old December 9th, 2004, 11:54 PM   #5
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Fred, what a beautiful explanation.
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Old December 10th, 2004, 05:41 AM   #6
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See also http://www.dplay.com/dv/balance/balance.html
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Old December 12th, 2004, 01:14 AM   #7
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Thanks a ton. I know a thing or two about shielding, but I had no idea it could run thru unbalanced audio. Thanks a ton.
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