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Noisy XLR plug

M

mr.chill

New Member
Just tried to make som DIY xlr plugs. When i plug the male connector into the amp it makes a noise when i touch the plug itself, its like a ground loop noise, and its there when i touch both the male and female plug.

I have checked the pins and theres no connection between any of them or the plugs itself, so the plugs seems fine.

I have soldered the ground to pin 1, the hot to pin 2, the cold to pin 3 just like normal on both plugs (female and male).

Is the noise normal for some plugs when you touch them? The cable Is fine as long as I dont touch the plugs.
 
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I have soldered the shield aswell to pin one. Or what do you mean by shell, and metal tab? Do you have a picture?
 
Looks like I have fixed it, I soldered the pin 1 to the XLR plug chassis aswell on both ends, this removed the problem. Was this what you meant?

I have searched around for the fix, and seems like some people say you should not do it and others say you should. Oh well now it works.
 
Jon_Logan said:
You also need to solder the metal tab to pin 1. The metal tab touches the shell, grounding it.
Click to expand...

True - but on the Switchcraft plugs the screw that holds it together grounds the tab to the shell, correct? (this is the screw that sort of screws out from the plug, into the shell.)

On nuetrik style plugs - I dont think there is any shield to the shell...I think the thin metal casing around the plug does that
 
Yes, the "Shell" is the metal body that is the outside of the connector. What you call "chassis".
The "Tab" is the metal terminal that isn't pins 1,2, or 3. It makes an electrical connection to the shell, extending the ground to the shell.

When the shell wasn't grounded, your body touched the shell. You are basically an antenna. You bring a noise source near your wires that have been pulled out of their shield. When you ground the shell, the shell shunts all of your antenna-like noise pickup to ground.

Some have said, "You shouldn't ground the shell"? I don't see any good reason not to ground the shell. Just sounds lazy to me.

There is only one reason I can think of to not ground the shell. That is to avoid ground loops. This is better done on a balanced interface. Not just XLR connectors, but when using twisted pairs. In that case, you don't even need to land the grounds (pin 1). You can just + and -.
 
When ever I've had this problem - it usually meant I got one of the wires too hot, melted the casing, and have shorted hot to ground (for example)...and touching it will buzz...kinda like touching the unplugged end of a guitar cable.
 
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