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Sound Reinforcement - Forums for Live Sound Professionals - Your Displayed Name Must Be Your Real Full Name To Post In The Live Sound Forums => LAB: The Classic Live Audio Board => Topic started by: Brian Larson on April 06, 2011, 07:23:18 pm

Title: Two channels in a 5 pin XLR?
Post by: Brian Larson on April 06, 2011, 07:23:18 pm
Has anyone ever used a 5 pin XLR to send two channels of mic level signal?

Im thinking of building a stereo DI with a 5 pin XLR output and a separate breakout that goes from 5 pin to two 3 pin.

If i can run one cable instead of two it would cut down on some stage clutter, especially for festivals/ battle of the bands.

I would theoretically just combine the two shields on one of the pins.

Do you think there would be crosstalk issues?

What cable would you recommend using?

Thanks!
Title: Re: Two channels in a 5 pin XLR?
Post by: Justice C. Bigler on April 06, 2011, 08:05:30 pm
I've seen stereo mics with a 6-pin XLR connector. But they always used a special double cable (like headphone cables with two separate cables fused together).  I'm not sure that combining the ground conductors would be such a great thing.
Title: Re: Two channels in a 5 pin XLR?
Post by: Tim Weaver on April 06, 2011, 08:33:22 pm
Years ago we used 7 pin XLRs for a triamp driveline. It worked fine. It was line level, so I don't know if that would change anything, but I don't think it would.

iirc, we used 3 channels of hot and cold and only had the shield connected on the upstream side. This left the grounds lifted at the amps. We ran these from the snake head to each amp rack. One of them was 75 feet I think.
Title: Re: Two channels in a 5 pin XLR?
Post by: Gus Housen on April 06, 2011, 08:38:40 pm
instead of creating another cable to lose why not consider making a 2 ch snake, I have a couple and they are handy for what  you are talking about and besides if somehow someone forgets the special cable or 1 ch goes bad (or you want to use a standard cable tester)  It only takes a 2nd to plug in the extra connector.
Title: Re: Two channels in a 5 pin XLR?
Post by: Dave Bigelow on April 06, 2011, 09:45:22 pm
That is exactly how the AT dual element mics are wired, one 5 pin on the body of the mic that breaks out to two 3 pin connectors.

Obviously the shield is shared.


edit: described it a little better.
Title: Re: Two channels in a 5 pin XLR?
Post by: info@travelingmonkeysound.com on April 06, 2011, 10:17:15 pm
That is exactly how the AT dual element mics are wired, one 5 pin on the body of the mic that breaks out to two 3 pin connectors.

Obviously the shield is shared.


edit: described it a little better.

The shure VP88 also does this. I'm sure it's all fine for time aligned stereo mics but maybe not the best idea for combining different sources that will get amplified a lot.

Is there something wrong with sub snakes and looms?
Title: Re: Two channels in a 5 pin XLR?
Post by: Tim Padrick on April 06, 2011, 10:22:47 pm
I'm sure it will work.  But not only will you have an oddball cable that you need to keep track of, you'll need a spare or two.  Just make a 2-pair snake.
Title: Re: Two channels in a 5 pin XLR?
Post by: paul bell on April 06, 2011, 10:47:56 pm
Like Tim, I use 7 pin XLR cabling as the drive line in my tri-amped system. The cabling is a four pair snake cable-as nobody makes a three channel flexible snake cable. Shared shield/ground. It makes for quick plug & play setups.

It works-well. I don't see why it wouldn't also work for the OP's proposed use. There are 2 channel snake cables on the market.

It was fun drilling the plug chucks bigger to fit the cable.
Title: Re: Two channels in a 5 pin XLR?
Post by: Dave Bigelow on April 07, 2011, 12:24:20 am
I'm sure it will work.  But not only will you have an oddball cable that you need to keep track of, you'll need a spare or two.  Just make a 2-pair snake.

I agree with Tim. Even if I used the mics that Nils and I mentioned I would still be running two normal 3 pin cables.
Title: Re: Two channels in a 5 pin XLR?
Post by: Geoff Doane on April 07, 2011, 10:46:11 am
There is no technical problem with doing it, but I share other's concerns about needing an odd-ball cable.

5-pin XLRs have been used for years on stereo mics, and with balanced lines, you don't need to be concerned about crosstalk, even if the pairs aren't individually shielded.  Foil shielding is only effective for RF anyway, not audio frequencies.

I've measured crosstalk on Canare quad cable at better than 100 dB (about 50 feet of cable, 100-10kHz).  You get the best results with the two blue wires as one pair, and the two whites for the other, but it only degrades slightly if you wire it the other way.

GTD