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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: Ray Soly on April 29, 2017, 12:16:57 pm

Title: 48V phantom noise during show intermittent
Post by: Ray Soly on April 29, 2017, 12:16:57 pm
had this happen yesterday during show : http://vocaroo.com/i/s0TYQ9TrLCeY could not track down which condenser mic other than it was on left side of conductor...possible causes ? mic, cabling ?  both ? mics go to pit subsnakes /patch bay/ 40 prs / foh.....

Ray
Title: Re: 48V phantom noise during show intermittent
Post by: John Roberts {JR} on April 29, 2017, 01:21:56 pm
Flaky pin 1 in mic cables can cause phantom power noise.

JR
Title: Re: 48V phantom noise during show intermittent
Post by: Ron Hebbard on April 29, 2017, 01:35:47 pm
Flaky pin 1 in mic cables can cause phantom power noise.

JR
I learned from experience that, given enough years, the braided shield on Belden 8412, 8413 and 8402 corrodes and disintegrates into a grey powdery, non-conductive mess.  Granted these were long cables, 100' and longer, with very little use over 25 to 30 years.  Until very recently they were still sitting on the bottom of the cable trunk and worked with dynamic mics but not with anything requiring phantom powering.
Toodleoo!
Ron Hebbard.
Title: Re: 48V phantom noise during show intermittent
Post by: Mike Caldwell on April 29, 2017, 08:24:43 pm
I learned from experience that, given enough years, the braided shield on Belden 8412, 8413 and 8402 corrodes and disintegrates into a grey powdery, non-conductive mess.  Granted these were long cables, 100' and longer, with very little use over 25 to 30 years.  Until very recently they were still sitting on the bottom of the cable trunk and worked with dynamic mics but not with anything requiring phantom powering.
Toodleoo!
Ron Hebbard.

Yep I've tried re-terminating a couple cables like that, the braid just kept crumbling away.
Title: Re: 48V phantom noise during show intermittent
Post by: Kevin Maxwell on April 30, 2017, 01:19:39 pm
had this happen yesterday during show : http://vocaroo.com/i/s0TYQ9TrLCeY could not track down which condenser mic other than it was on left side of conductor...possible causes ? mic, cabling ?  both ? mics go to pit subsnakes /patch bay/ 40 prs / foh.....

Ray

What console are you using? Is this an install or a portable system tied into an install?

Usually when you have a cabling problem with a mic that requires phantom power it will cause the input to clip. If you have a digital console that has the capability to see all of you input meters on one page and if it has peak hold capabilities you should be able to see this as or just after it happens.

Bad cable of bad patch bay or bad mic. I had an AKG mic that had the ground on the little PC board inside the mic get cracked because someone had wrapped the mic cable around the stand and when someone went to adjust the mic there was too much tension and it cracked the ground inside the mic.

Now it is time to find the problem you will need to test, have someone move the connectors around on all of the cabling and mics and at the patch bay while you watch the input meters.
Title: Re: 48V phantom noise during show intermittent
Post by: Ray Soly on April 30, 2017, 07:30:42 pm
What console are you using? Is this an install or a portable system tied into an install?

Usually when you have a cabling problem with a mic that requires phantom power it will cause the input to clip. If you have a digital console that has the capability to see all of you input meters on one page and if it has peak hold capabilities you should be able to see this as or just after it happens.

Bad cable of bad patch bay or bad mic. I had an AKG mic that had the ground on the little PC board inside the mic get cracked because someone had wrapped the mic cable around the stand and when someone went to adjust the mic there was too much tension and it cracked the ground inside the mic.

Now it is time to find the problem you will need to test, have someone move the connectors around on all of the cabling and mics and at the patch bay while you watch the input meters.

Hi Kevin,

we did all the cable/patch cord wiggling , digital console but I can only fit 16 meters on the built in screen.  never occurred again….last couple of shows went fine…..and now we're out of that venue….my FOH, their mics, cables and PA



Ray