balancing?

[kbywg]

what is the diff between 3-wire differentially balanced and 3-wire impedance balanced when building interconnect cables for components to mixer?

 

[kbywg]

WoW 34 views and no answer. Well I don't feel so bad about not knowing this terminology now. I mix live audio to audience sizes ranging from press conference to arena concert rock and I have never heard these terms mentioned until a few days ago when I was reading through an Allen Heath mixer manual and they were indicating ways of interconnecting the console with outboard gear. I thought audioholics would be a place where the forum readers would jump all over this question with replies. Anybody have a suggestion as to where to go for this answer. It's not a make or break question so I'm in no hurry, just very curious.
Thanks.

 

[JoeE SP9]

It may be you are asking the wrong question. A balanced cable needs balanced inputs and outputs on the devices connected. This requires 3 conductors. A plus a minus and a shield/ground conductor. Any other cable needs only 2 conductors. A signal conductor and a ground. Unbalanced cables that have three conductors usuall have the third conductor connected at only one and as a drain. The third conductor is connected at the source end.
Balanced cables and connections are differential with no direct ground reference. Unbalanced connections are referenced to ground.

 

[kbywg]

Thanks for the response. I understand your statement clearly.
Here's the exact quote referring to the console connectors.
"All input and output XLR connectors are 3-wire differentially balanced. These have 3 connector pins: pin 1 = ground (cable screen), pin 2 = signal +ve, pin 3 = signal -ve
All the master output jack connectors are 3-wire impedance balanced. These have 3 connector pins: tip = signal +ve, ring = signal -ve, sleeve = ground (cable screen)."
So they are saying ALL the connectors are balanced but there is a difference between the XLR and TRS 1/4" jacks in that the XLR are differentially balanced and the TRS 1/4" jacks are impedance balanced. Have they made a misprint (quite possible) or if not then what is the difference in those 2 different kinds of balancing?

 

[kbywg]

The manufacturer responded with the following.
"The Main, XLR Outputs are electronically balanced. And there's an
optional upgrade for the aux outs, to have these electronically
balanced also. Meaning, the outputs are IC transformer isolated and
balanced.
Impedance balanced is achieved through a simple resistor circuit.
The differences would be in the output levels, electronically balanced
being at a +4dBu and impedance balanced at -2dBu. Also, if running long
cable distances, electronically balanced systems will have better noise
cancelling features."

Anyway, thanks for the space.