At a venue I regularly play at, I use a DI/Bass Driver, and recently I’ve acquired a ground loop in the setup. I have an XLR connect that goes to the house and a 1/4” connector going to my bass amp as a monitor.
After some consulting with the manufacturer and Sweetwater, it was determined that all my XLR cables are grounded to the casing of the XLR connector and when I plug those cables into my DI box the casing was shorting the ground and defeating the ground lift switch.
After talking to the support engineer, it was suggested I have the wrong kind of XLR-3 cable. Another support engineer suggested that I just need a more expensive-better-built cable.
My question is: Is there’s really 2 kinds of XLR cables? Or is it just the luck of the draw which cable you buy? I got into the habit of carrying a small multi-meter with me to see if there is a connection between pin 1 and the casing.
I initially solved this by using a hum-eliminator box, but I acquired a house branded cable from Sweetwater that works “correctly”.
Not a big sound system guy but my understand is there are grounded xlr cables for use on equipment with ungrounded chassis. I’m sure someone will weigh in on this
@DaveT ??
Hey. Where has he been?
Oh, I’m usually lurking and liking. With it being year-end, I’ve been cranking out the system proposals to the bitter end. For some reason the sales dept. really likes making their numbers.
Here’s what Neutrik has to say about this:
On an XLR connector Pin 2 carries the positive going signal, Pin 3 carries the negative going signal and Pin 1 carries the ground.
Pin 1 does not need to be connected at both ends to pass a balanced signal. Its purpose is to drain the noise picked up by the cable shield. If it is connected to ground at one end, the noise will drain. For the cable going to FOH, it’s best to let them drain the shield at their end and either use the ground lift switch on the DI or cut the shield wire off pin 1 inside the connecter at the DI end, bend it back and shrink wrap it so it can’t accidentally touch anything.
If the DI box doesn’t have a ground lift switch, take a short XLR M-F cable and cut the shield on pin 1 where it connects to the DI box. This can be carried in the kit as a ground lift cable to make up for not having a switch.
This is probably more than anyone really wants to read:
It’s also possible to look inside the connector shell to see if the shield is soldered to both pin 1 and the shell connection tab.
I just re-read your post and I realized I didn’t really answer it. You can cut the bridging connection between pin 1 and this tab and the ground lift switch will work again.
I don’t know how to tell if a given cable has it connected or not without inspecting it. In audio systems where we make all the cables we never connect it. I’d guess that most high end mic cables would have it connected for the mic casing.
Thanks to all for the insight and information.
Assuming a meter on each end pin would do the trick, no?
I’m counting that as inspection as opposed to knowing some kind of designation before purchasing.
The multimeter test would be from Pin 1 to the connector shell for this particular problem. The shell contact to the device case is bypassing the ground lift switch.