POLL! XLR Assembly: Connect Pin1 to Shell? Yay or Nay?

[Derek H]

Thanks for voting!

Other threads discussing this topic:

on jwsound:http://www.jwsound.net/SMF/index.php?topic=3646.0

and on RAMPS:http://groups.google.com/group/rec.arts.movies.production.sound/browse_thread/thread/2c651ff19e70e022/a516316515adfcbc?lnk=raot#a516316515adfcbc

[John Steigerwald]

I voted no, but not for any technical reason.

I've just never done it when making any cables and haven't had any issues.

[Eric Toline]

Nope and no problems. (something about "if it ain't broke....."

Eric

[Glen Trew]

Sorry to pop the bubbles of the majority of poll voters, but, for remote film/video production sound using modern professional equipment (made since the 1980's) there is no valid reason to leave the shells of XLR audio connectors ungrounded, and several good reasons to ground them.

What would the responses have been if the poll had asked, "Would you prefer using mic cables that have several inches of unshielded conductors?" Of course, all answers would have been no. But this is exactly what happens when two XLR cables are connected together with ungrounded shells. There are other reasons to ground the shells of audio XLR connectors, but this one should be enough.

Clearly, from the responses in the previous posts, the risks of ungrounded audio XLR shells can go unnoticed for entire careers. But even though I could usually get an acceptable signal in the short distance between a mixer and a recorder with a couple of clothes hangers and paper clips, (and have had to resort to something similar when I've run out of proper cables), we should stack the odds in our favor by grounding the shells.

There is an recent exhaustive discussion of this topic on ramps. So, rather than re-posting everything here, I suggest checking it out there.

Glen Trew

[John Steigerwald]

Sorry to pop the bubbles of the majority of poll voters, but, for remote film/video production sound using modern professional equipment (made since the 1980's) there is no valid reason to leave the shells of XLR audio connectors ungrounded, and several good reasons to ground them.

No bubble popped   I didn't say it was a bad idea to do it, just that I never have.

Clearly, from the responses in the previous posts, the risks of ungrounded audio XLR shells can go unnoticed for entire careers. But even though I could usually get an acceptable signal in the short distance between a mixer and a recorder with a couple of clothes hangers and paper clips, (and have had to resort to something similar when I've run out of proper cables), we should stack the odds in our favor by grounding the shells.

I think there's a difference between unnoticed and unproblematic.

In a large concert scale sound system we regularly had racks of gear, the stage inputs and the amp distros interconnected with literally hundreds of balanced mic cables, not to mention the 360' 52 pair run to the mix position.  No shell grounds, no issues.

I don't doubt that there are scenarios where it makes a difference, but it's been my experience for 20+ years that generally it doesn't.

Your mileage may vary.

[Michael P Clark]

I would like to add that having the shell grounded is a good idea and is mostly only done on cables I got from the dealer I buy from. I actually do it myself on all of my cables, after I noticed that my dealer did them, figured if they are doing it, I must have missed something in school. I actually don't buy cables anymore, I just make them myself. However, what confused me the most, is that when I was in school, this topic was never brought up as an issue or a MUST for that matter. What WAS drilled into our heads is, Twisted Pairs are the best microphone cable to be used, because it keeps RF out better and lower noise. Twisted Pairs = Low Noise. Guess how many Twisted Paired Microphone cables I received from my dealer? ZERO!!! That never changed my mind on that issue, and I always use Braided Twisted Pairs, probably more important than grounding the shell. If I am wrong here I am sure I will be corrected, it's been done before:)

I am also confused as to why someone would only do the grounding on ONE side of the cable and not the other.

[Glen Trew]

I would like to add that having the shell grounded is a good idea and is mostly only done on cables I got from the dealer I buy from. I actually do it myself on all of my cables, after I noticed that my dealer did them, figured if they are doing it, I must have missed something in school. I actually don't buy cables anymore, I just make them myself. However, what confused me the most, is that when I was in school, this topic was never brought up as an issue or a MUST for that matter. What WAS drilled into our heads is, Twisted Pairs are the best microphone cable to be used, because it keeps RF out better and lower noise. Twisted Pairs = Low Noise. Guess how many Twisted Paired Microphone cables I received from my dealer? ZERO!!! That never changed my mind on that issue, and I always use Braided Twisted Pairs, probably more important than grounding the shell. If I am wrong here I am sure I will be corrected, it's been done before:)

I am also confused as to why someone would only do the grounding on ONE side of the cable and not the other.

I would be surprised if you have received shielded pair XLR cables that do not use a twisted pair. The tightness of the twist (number of twists per meter) required for audio cables might not be so appearant as in CAT5 cable, but the twist is usually in the spec.

I wonder if you are thinking about starquad cable, which uses twisted conducters (typically 2 blue, 2 white) within each pair. Since the intention with starquad cables is to combine same colored conductors at the connector, they are not usually thought of as a "pair". Not all XLR cables use the starquad conductor scheme. For noise rejection, I think starquad is always best. But some people may prefer nonstarquad for a couple of reasons including lower cost and smaller cable size, particularly when used for line level signals, such as in ENG break-away cables.

For example, the 3-pair cable that Remote Audio had made for their ENG break-away cables uses shielded twisted pairs, but does not use starquad pairs because doing so would make in impossible to fit into a Neutricon or 7-pin XLR connector. But, for the Remote Audio Talkback and Boom Cable system, a 2-pair starquad cable is used (currently Canare), where one starquad pair is dedicated to the boom microphone signal and the other 5 conductors of the second starquad pair are used for monitoring and talkback.

Glen Trew

[Bartek]

Derek nice to see you on the forum!

I've always grounded my shells, for the cables i've made. But I did notice that most cables that I've bought in the past (i rarely buy made cables these days) did not ground their shells. I figured it was for a reason, or at least thats what i made myself to believe.

I did for some reason forget to ground the XLR chassis on my custom recorder enclosure, and guess what since the case is conductive, in certain situations whenever I touch the case while powered up, I can hear a very faint, high freq squelch in my headphones. So guess what I'm doing this weekend.

u gonna come out and play on Tuesday?

[Derek H]

I'd love to but I'm on a show and they just flippy-flopped some schedule around and now I'm working Tuesday at 1pm!!  Sucks but work is work.  Mohundro is going to take notes for me.  Hope to see you soon!

[Steve Payne]

I am also confused as to why someone would only do the grounding on ONE side of the cable and not the other.

This is to prevent a ground loop between two pieces of equipment. Leaving the shield attached to one ground allows it to work.

[traut]

Years ago, Bruce Bisenz told me to always ground the shell.