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geoff geoff is offline
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Default Test XLR audio source for true differential signal?

On 24/06/2019 12:48 PM, Mike Rivers wrote:
On 6/23/2019 6:52 PM, Bob wrote:
Given a XLR audio source, what is the easiest way to test if it's a
balanced and differential signal vs a non differential signal?


It's differential if you get signal between pins 2 and 3. Balanced is
more complicated. The requirement for a connection to be balanced isn't
about voltage, it's about impedance relative to a common point,
typically pin 1. There are several configurations that are balanced. You
can test it using a multimeter.

If it's a transformerless output and the connector is wired in the
conventional manner, there will always be a signal between pins 1 and 2.
There may or may not be a signal between pins 1 and 3. Once you've
determined that pin 2 is "hot" you can measure the resistance between
pins 1 and 3. If it's zero, then the connection is not balanced. If it's
more than just a couple of ohms, then it's probably balanced.

If it's a transformer output, it's fair to assume that it's balanced. If
the transformer doesn't have a grounded center tap, you can get
confusing readings between pins 2 and 3 to pin 1.

Here's an article I wrote many years ago about balanced and unbalanced
connections:

https://mikeriversaudio.files.wordpr...ed_revised.pdf



Or is he assuming it is balanced and differential, but anxious about the
'accuracy' of the differentiality ?

geoff