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Author Topic: Distance between electrical and audio cables  (Read 33858 times)

Alex Donkle

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Distance between electrical and audio cables
« on: January 14, 2015, 04:08:48 PM »

More of a poll type question, but has anyone here ever come across sound system hum or buzz that was caused by audio cables running next to power cables? Best practice has always been separate the cable types whenever possible for several reasons (including safety), but I've also never seen it actually cause noise problem problems for the sound system when dealing with balanced cables, correctly wired. Nearly all sound system hum I've come across relates to grounding issues. Has anyone ever witnessed a noise issue that was fixed by just moving audio cables further away from power cables?
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Mike Sokol

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Re: Distance between electrical and audio cables
« Reply #1 on: January 14, 2015, 05:24:34 PM »

More of a poll type question, but has anyone here ever come across sound system hum or buzz that was caused by audio cables running next to power cables? Best practice has always been separate the cable types whenever possible for several reasons (including safety), but I've also never seen it actually cause noise problem problems for the sound system when dealing with balanced cables, correctly wired. Nearly all sound system hum I've come across relates to grounding issues. Has anyone ever witnessed a noise issue that was fixed by just moving audio cables further away from power cables?

When I used to do a lot of political gigs in DC the lighting guys would lay their cables right on top of my mic lines. That would cause a lot of dimmer hash in the pre-amps. I changed to Canare Star-Quad cable for those runs and that problem went away.   

I did have a problem with a stage that had a big 6" AC power conduit running right under where the bass guitar player stood. When he turned on stage his bass would be quiet or hum like crazy, depending on how his pickups lined up with the path of the conduit under his feet. I corrected the problem by having him switch to the opposite side of the stage.

TJ (Tom) Cornish

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Re: Distance between electrical and audio cables
« Reply #2 on: January 14, 2015, 05:24:46 PM »

More of a poll type question, but has anyone here ever come across sound system hum or buzz that was caused by audio cables running next to power cables? Best practice has always been separate the cable types whenever possible for several reasons (including safety), but I've also never seen it actually cause noise problem problems for the sound system when dealing with balanced cables, correctly wired. Nearly all sound system hum I've come across relates to grounding issues. Has anyone ever witnessed a noise issue that was fixed by just moving audio cables further away from power cables?
AC mains cables?  No.  Dimmers?  Yes.
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TJ (Tom) Cornish

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Re: Distance between electrical and audio cables
« Reply #3 on: January 14, 2015, 05:25:41 PM »

I did have a problem with a stage that had a big 6" AC power conduit running right under where the bass guitar player stood. When he turned on stage his bass would be quiet or hum like crazy, depending on how his pickups lined up with the path of the conduit under his feet. I corrected the problem by having him switch to the opposite side of the stage.
All bets are off for single-ended guitar pickups, which are some of the most efficient antennae ever invented by man.  :)
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Mark Cadwallader

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Re: Distance between electrical and audio cables
« Reply #4 on: January 14, 2015, 05:58:14 PM »

Echoing TJ, I have had induced noise through the Clear-Com when I have been too close to the cables powering conventional stage lighting (i.e., dimmers) when up on the fly rail in a theater.   Moving 2' seems to solve the problem. Mark C.
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Lee Buckalew

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Re: Distance between electrical and audio cables
« Reply #5 on: January 14, 2015, 06:04:51 PM »

Echoing TJ, I have had induced noise through the Clear-Com when I have been too close to the cables powering conventional stage lighting (i.e., dimmers) when up on the fly rail in a theater.   Moving 2' seems to solve the problem. Mark C.

Standard Clear Com is not a balanced audio signal.

Lee
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Mac Kerr

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Re: Balanced Comm
« Reply #6 on: January 14, 2015, 06:08:35 PM »

Standard Clear Com is not a balanced audio signal.

Nor is Clear Com TW, or RTS. AFAIK the Teles AudioCom is the only balanced belt pack intercom system.

Mac
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Mark Cadwallader

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Re: Distance between electrical and audio cables
« Reply #7 on: January 14, 2015, 06:30:41 PM »

Standard Clear Com is not a balanced audio signal.

Lee

Point well taken. I wasn't thinking about it being unbalanced. Duh!  Mark C.
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Lyle Williams

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Re: Distance between electrical and audio cables
« Reply #8 on: January 14, 2015, 06:35:17 PM »

The 2' suggested is adequate.  If possible power and signal cables should not cross each other, or cross each other at right angles.

But people get away with other setups all the time.  I have power taped to my snake along with ethernet and rf coax.
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Tim McCulloch

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Re: Distance between electrical and audio cables
« Reply #9 on: January 14, 2015, 06:39:31 PM »


But people get away with other setups all the time.  I have power taped to my snake along with ethernet and rf coax.

Done this for longer than there has been ethernet... ;)

As has been said, dimmers fully loaded and running at 50% are the worst things for noise (and newer dimmers are far less of a problem).  Normal AC service has yet to create any noticable induced noise in our systems.
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Re: Distance between electrical and audio cables
« Reply #9 on: January 14, 2015, 06:39:31 PM »


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