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Re: Which XLR Pin Is Hot?

Posted by SJK (A) on January 3, 2002 at 02:45:31

In Reply to: Re: Which XLR Pin Is Hot? posted by RBP on January 3, 2002 at 00:26:05:

When I made the cable from crossover XLR out to
power amp RCA in, I discovered that the pin 3
is the positive/hot! (the XLR to RCA was:
pin2 <--> RCA hot, pin 1 <--> RCA ground, the
cable braid shield only connected to pin 1 and
there is no sound came out of speakers untill
I connected the pin 3 to RCA hot). Out of curiosity,
I used voltmeter to measure the pins and found out
there are volt (in mv) among the output pins of
crossover: for example
pin 3 --> pin 1: + 5.9
pin 3 --> pin 2: + 5.9
pin 1 --> pin 2: 0.0
pin 2 --> pin 1: 0.0
These seem to indicate that the XLR output had been
alter to unbalanced (RCA) output?

I was puzzled when I measured the XLR input of crossover
(my pre-amp only has RCA output so I need to know which
XLR pin I should connect to the RCA hot):

pin 1 --> pin 3: + 1.0 (pin 3 --> pin 1: - 1.0)
pin 3 --> pin 2: + 0.7 (pin 2 --> pin 3: - 0.7)
pin 1 --> pin 2: + 1.7 (pin 2 --> pin 1: - 1.7)
This "leakage volt/current" measurement seems
to say the pin 1 is positive which should connect to
RCA hot?

Also, ONLY one of the XLR ouput is unique (there are 4 XLR
outputs per unit, so there are total 8 XLR outputs for
2 units):

pin 1 --> pin 3: + 9.5
pin 2 --> pin 3: + 9.5
pin 1 --> pin 2: 0.0
pin 2 --> pin 1: 0.0

Is this to say that this only oupt had been altered so
that both pin1 and pin2 are positive and I can connect
one of then to RCS hot and pin 3 to RCA ground?

If these measurements is useless in finding the XLR positive
pin, due the fact that the all the 7 outputs (but the one
indicated above) are pin 3 positive, can I assume that the
XLR inputs also with pin 3 positive? Or, is there any way
to find out which XLR is positive?

-- SJ

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