# XLR Pin 2/3 Hot Question



## hollowbody (Jan 15, 2008)

I recently bought a Mackie CR1604 and the manual says the balanced outs are wired pin 3 hot instead of pin 2, but since this is an older unit and the previous owner had some mods done to it, I wanted to know 2 things:

1 - is there a way I can check which pin is hot? Do I need any special equipment for this?

2 - if it IS pin 3 hot, do I risk any potential damage connecting it to a powered speaker that is expecting pin 2 hot, or will be just be out of phase?

I'm planning on buying some 1/4" TRS to XLR cables and rewiring the XLR side to invert polarity, but I wanted to be able to determine what I need more accurately before I go buying cables and busting out the iron.

Thanks!


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## Jim DaddyO (Mar 20, 2009)

I use a 1604 too. Plug the XLR in and go (remember to set the input level). If you need any adapters (XLR to TRS, or 1/4 mono) just use them as is. Pin 1 is earth, pin 2 is the + side (left if converting to a stereo cable such as RCA), pin 3 is the - side (or right for stereo). Here is a resource for you to bookmark.
Audio Cables and Connectors


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## hollowbody (Jan 15, 2008)

Jim DaddyO said:


> I use a 1604 too. Plug the XLR in and go (remember to set the input level). If you need any adapters (XLR to TRS, or 1/4 mono) just use them as is. Pin 1 is earth, pin 2 is the + side (left if converting to a stereo cable such as RCA), pin 3 is the - side (or right for stereo). Here is a resource for you to bookmark.
> Audio Cables and Connectors


On these older 1604 (the CR series, not VLZ) the hot for the main outs is pin 3. Or at least that's what the manual says. I'm going to rewire some cables and see what happens.


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## dtsaudio (Apr 15, 2009)

There won't be a problem using it as is. However all signals will be out of phase. To some this is audible (they claim). Hot is a bit of mislabel. Both pin 2 and pin 3 are hot, just 180 dgrees out of phase referenced to ground (pin 1)


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## Big_Daddy (Apr 2, 2009)

Hollowbody, if you don't have one, get a cable tester like this guy...










I've had one for over 30 years now and it has been one of the best investments I've ever made. At the very least, it will tell you exactly what the pin assignments are on every one of your cables. I think as long as the cable pins are all the same, especially with XLR's, you should be fine.

Edit: The tester I use has a button to cycle each pin/led on or off (9 volt battery equipped). The above unit doesn't have this feature.


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## hollowbody (Jan 15, 2008)

dtsaudio said:


> There won't be a problem using it as is. However all signals will be out of phase. To some this is audible (they claim). Hot is a bit of mislabel. Both pin 2 and pin 3 are hot, just 180 dgrees out of phase referenced to ground (pin 1)


Yeah, I guess if both channels are the same, there shouldn't be an issue. I just didn't know if the monitors or PA cabs we were using would explode if fed a signal with a different polarity.



Big_Daddy said:


> Hollowbody, if you don't have one, get a cable tester like this guy...
> 
> 
> 
> ...


Hmm, for $50, seems like a good idea! I've seen the Behringer cable tester at L&M and thought about one of those. 

To be on the safe side (and before seeing these two posts) I rewired a pair of my XLRs and marked them reverse polarity to use with the L/R outs on my Mackie. I've only been getting into PA gear recently and it's all new and strange to me.


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## spizznel (Sep 21, 2011)

*Polarity is CRITICAL*

Pin 2 is hot in almost all exceptions. Mackie does however make pin 3 hot and with their powered speakers the input is also pin 3 hot so using them alone you are phase correct. On the inputs I am not sure, standard phantom power puts the + voltage on pin 2 and (-) on pin 3 so I can not imagine pin 3 being hot on Mackie's inputs... who knows. It is critical that phase always be correct! If your PA is reverse phase, the ambient sound from a kick drum mixed with the mains will be phase reversed, and even more important, a direct box out of the bass guitar will make the bass amp speakers out of phase with the mains. Big Problem! With Mackie boards going balanced to the inputs of another brand power amp or powered speakers will be out of phase and if you use other brands to supplement Mackie Speakers at the same time, they will be out of phase with each other. That is a total nightmare. It has​ been my experience with Mackie to make phase flop cables when using their boards with any other gear.


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## spizznel (Sep 21, 2011)

[h=3]Three pin - audio[/h]
Left to right: Cannon XLR3-12C (line),Switchcraft X3F (line), Neutrik NC3MP panel, Neutrik NC3FP panel​


XLR and 0.25 in TRS combo jack.​
EIA Standard RS-297-A describes the use of the XLR3 for balanced audio signal level applications:

  1Chassis ground (cable shield)2Positive polarity terminal (_hot_)3Return terminal[SUP][5][/SUP] (_cold_)

PinFunctionPrior to the introduction of this standard, the wiring of pins 2 and 3 varied. The pin 2 "hot" and pin 3 "cold" convention was typically used by European and Japanese equipment manufacturers, but American companies used pin 3 "hot" and pin 2 "cold". This caused problems when interconnecting equipment with unbalanced connections. The pin 3 "hot" convention is now obsolete but is still found on vintage equipment. Pin 1 has always been ground, and many connectors connect it internally to the connector shell or case.


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