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Re: KM100 series wireless Phantom Power problem
Author: Martin Schneider/Neumann
Date: 01/07/2012
Hello again,

yes, David is correct.

As, to my knowledge, there is no "standardized" wording I use these terms:
- impedance balanced (identical impedances on pin2 + 3): absolutely essential for all interference issues
- signal balanced (positive polarity signal on pin2, inverted polarity on pin3): has no influence on interference immunity.

[To quote Bill Whitlock of Jensen Transformers: "The signal symmetry of this, or any other, balanced line driver has nothing to do with ground noise rejection."]

The point why balanced lines were adopted in professional applications was "impedance balance", and not "signal balance". As, in the old days, transformer coupling was always used for inputs and outputs, one got used to the assumption that "balanced" also implies "signal balance".

The "impedance balanced / signal unbalanced" topology is used by a number of microphone manufacturers, not only by us.

That the KM100 has the "pin3 hot" topology was due to availability of components, circuits, space and time, at the time the KM100 was designed (~1988). At that time, unbalanced inputs were hardly ever seen in professional applications, so the question of polarity reversal hardly ever arose.

All post-1992 circuits have a "pin2 hot" topology.

[Note: If anybody knows of a small, centre-tapped, 1:1 transformer for mic signals, that would fit inside an XLR barrel, please contact me... ]

Best regards,
Martin Schneider / Neumann Mic. Development  
 
Reply
Craig Stauffer
01/05/2012
Uwe Sattler/NeumannUSA
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Craig Stauffer
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Uwe Sattler/NeumannUSA
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Martin Schneider/Neumann
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Craig Stauffer
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       sent 
Martin Schneider/Neumann
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Uwe Sattler/NeumannUSA
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Uwe Sattler/NeumannUSA
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