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Author Topic: hum buzz in sound system  (Read 2375 times)

edward ruiz

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hum buzz in sound system
« on: November 04, 2014, 12:27:29 pm »

???? i have sound system powered with spider boxes to a 70k gen, all is good no buzz. when i connect, par cans 300w or and 600 watt to elations dimmer paks, at full brightness get a sight buzz in sound system, gets louder as i dimm the par cans. what am i doing wrong???
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Mac Kerr

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« Reply #1 on: November 04, 2014, 12:34:25 pm »

what am i doing wrong???

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Ray Aberle

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Re: hum buzz in sound system
« Reply #2 on: November 04, 2014, 05:35:10 pm »

???? i have sound system powered with spider boxes to a 70k gen, all is good no buzz. when i connect, par cans 300w or and 600 watt to elations dimmer paks, at full brightness get a sight buzz in sound system, gets louder as i dimm the par cans. what am i doing wrong???

Nothing.

Well, you're powering conventional lighting from the same source as your PA is being powered from. A buzz in the PA from the dimmer packs is to be expected. You //might// be able to move lighting onto a separate spider box, but ideally, the entire lighting rig would be powered separately from PA.
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Luke Geis

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Re: hum buzz in sound system
« Reply #3 on: November 04, 2014, 05:43:19 pm »

Sound gets their own genie, lights get their own genie and video gets their own genie. If you only have one genie, each crew gets their own isolated distro. Sometimes you can get away by simply running each crew off a separate leg of power from the genie. Video is not as problematic with audio in general. Where the issue usually lays is when they are running 4X 10K projectors and enough computers and video hardware to make Nasa look like a chump.
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Ray Aberle

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Re: hum buzz in sound system
« Reply #4 on: November 04, 2014, 05:47:14 pm »

LED lighting solutions are also another good option.
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Tim McCulloch

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Re: hum buzz in sound system
« Reply #5 on: November 04, 2014, 09:53:23 pm »

Poorly designed and poorly filtered dimmers.  Also is the generator grounded, and the ground bonded to Neutral at the generator?
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Mike Sokol

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Re: hum buzz in sound system
« Reply #6 on: November 04, 2014, 11:02:33 pm »

Poorly designed and poorly filtered dimmers.  Also is the generator grounded, and the ground bonded to Neutral at the generator?

I used to have this problem when I did sound gigs for politicians in DC. The lighting guys always showed up after me and laid there big power cables right on top of my XLR mic lines. If there was a dimmer anywhere it would buzz in my otherwise quiet system. I solved this by building a bunch of 100-ft Canare Star-Quad cables which are great a ignoring magnetic coupling. See if you can isolate this to a single channel. For instance, one of my church gigs had similar noise from their choir mics. When I ran a new XLR cable to replace a rather iffy cable in the ceiling, all the dimmer buzz went away. So be sure that all your wiring is perfect and shielding is properly terminated. And a single mic line with an open leg is an invitation for any dimmer hash to "come on in".
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Re: hum buzz in sound system
« Reply #6 on: November 04, 2014, 11:02:33 pm »


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