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In Reply to: Which XLR Pin Is Hot? posted by SJK on January 02, 2002 at 11:30:57:
Pin 2 on a standared XLR should be signifyed as "hot" or + signal.Hope that clears this up for you....
Follow Ups:
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: 0.0Is 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
Sounds to me like pin 3 is the + and your pin 1 is the ground. Some of the older audio equip. like the older soundcraft mixers etc. used to use:
pin 3 +
pin 2 -
pin 1 gnd.But now days and on more modern equipment, it has become pretty much the standard this way:
pin 1 gnd
pin 2 +
pin 3 -Hope this helps.
Bill W.
Hi RBP, Bill,Thanks for the help.
But, for the XLR input which has pin 1 has the highest
positive voltage then pin 3, then pin 2, the pin 3 is
still positive? Or all it matters is the relative voltage
difference between pin 2 and pin 3? If this is the case,
then one of the XLR output which has pin 1 and pin 2 with
no voltage difference but both pins have positive voltage
relatively to pin 3, then this output is wired with pin 2
positive?What I am trying to figure out is that the measurements I
did means ANYTHING in terms of determining which pin is hot/
positive (i.e. can I use voltmeter to find out the XLR
positive pin for many customized or overseas equipments)?Sorry to drag this so long. Again, Thanks.
-- SJ
The issue of which pin is Plus or Minus has to do with the polarity (absolute phase) of the signal. If your gear has transformers then they connect one side of the secondary to the plus pin and the other side to the minus pin. If you put dual channel scope on both the plus and minus pins you would see the signal is present on both pins it is just inverted on the negative pin.Note: Both signals are going up and down, The only way to tell which one is which is to connect something like a kick mic to the cable and have someone kick the drum while you are watching it. The one that goes positive first is the plus signal.
Note: Some transformerless gear just connects the minus pin to some DC voltage (or ground) through a resistor and the live signal is on the plus pin.
Phil
The Audio Engineering Society (AES) issued a standard for the XLR Pins (s14-1992\.ANSI s.4.48.1991)
Pin 1 is ground or shield
Pin 2 is hot or positive
Pin 3 is low or negativeJust an FYI
While I agree with both posts concerning the adoption of Pin#2 as the standard Hot pin, there is much less "standardization" than anyone might believe. In my home studio it is very close to 50-50, half pin#2, half pin#3. (and I have a LOT of gear) The good news is that for casual work, it usually doesn't really matter as most things "work" even when connected pieces of gear conflict regarding the Pin polarity. But if you are doing professional work, you really do need to resolve this issue.
digital? I'm still not sure about transistors....
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