Wiring a XLR plug

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Hello everyone

I bought this Neutrik PCB mount 3 pole XLR plug from Premier Electronics. The XLR plug has 4 pins. As far as I know #1 pin should be connected to GND, #2 to Cold & #3 to Hot but I have no idea about #4 therefore would anyone please tell me what is the function or connection of the # 4 pin of this plug?
Thanks.
 

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Hello everyone

I bought this Neutrik PCB mount 3 pole XLR plug from Premier Electronics. The XLR plug has 4 pins. As far as I know #1 pin should be connected to GND, #2 to Cold & #3 to Hot but I have no idea about #4 therefore would anyone please tell me what is the function or connection of the # 4 pin of this plug?
Thanks.

That is actually a PC board mount jack so it will be a bit inconvenient to connect wires to. Pin 4 is the outer shell of the connector and it's generally connected to pin 1.

BTW in the US pin 2 is considered 'hot' and pin 3 'cold' but it's only a problem if the phase is reversed accidentally.

 
That is actually a PC board mount jack so it will be a bit inconvenient to connect wires to. Pin 4 is the outer shell of the connector and it's generally connected to pin 1.

BTW in the US pin 2 is considered 'hot' and pin 3 'cold' but it's only a problem if the phase is reversed accidentally.


Hi stratus

Thank you very much for your inputs. Yes I need the US connection therefore I will correct the pins to read as:
Pin 1: Gnd
Pin 2: Hot
Pin 3: Cold
 
The pin 1 problem Andrew mentioned has caused many a problem with RFI or ground loops. My favorite explanation to pin 1 problems is found in Rane's Handbook.

Grounding and Shielding Audio Devices

Hi Gray

This is a very good and clear diagram for wiring. Thank you for attach it here.

In this diagram, it has singal and chassis grounds, in addition, there will be a power ground, therefore there will have 3 grounds in an amplifier. Would anyone please correct me if I am wrong?
 
Enclosed is a schematic of the Unbalance to Balance Converter which I am going to build. It seems to me that the drawing of Input Signal and Input Ground is an error drawing. Would anyone clarify for it?

Thanks
 

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Personally I'd use lower value build out resistors - maybe 27 rather than 120 ohms and also delete the capacitors - but that's just me.


Hi stratus

What would be the different if change resistor value from 120 Ohm to 27 Ohm in this circuit? Please advice.
I do not feel comfortable with the 47uF capacitors too but as far as I know they are coupling capacitors for blocking the DC at output stage, deleting these capacitors probably will create a DC voltage to harm the power amplifier and speakers. What do you think?
 
I still see the XLR output pin #1 connected to audio (circuit) ground.
Pin #1 is not part of the audio circuit, it only connects to the chassis/enclosure. And then with a 2cm (or less) wire.

For my own use I use a low value resistor in the ground line. Most ground loop _Voltages_ are quite low but the currents can get high. A 10 ohm resistor in the ground line will drop those currents dramatically. Don't worry about hum. That's why you have balanced audio.

 
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