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Author Topic: Poor Man's Distro and Reverse Bootleg Ground situation?  (Read 3777 times)

Mike Sokol

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Re: Poor Man's Distro and Reverse Bootleg Ground situation?
« Reply #10 on: May 28, 2016, 06:43:42 am »

Wow, finding 4 circuits to pull power from? At that level I would be looking for a larger feed to a distro. The most I have ever found that were reasonable distances were 3 circuits.
Yeah, in most of the clubs I played in over the years there would be a line of receptacles across the back of the stage, but they were all powered by a single circuit breaker. And other receptacles in the room might be shared by the kitchen or lighting. This is still common in many of the churches I've taught in, and I've had my sound system taken down by someone in the kitchen turning on a commercial coffee urn which draws around 15 amperes by itself. Ugh...

That's also why ground loop hum seems to come on go randomly at times. Other things in the building can be turned on and off, creating different voltage drops on various circuits. If the ground and neutral is intermingled on a branch circuit (standard bootleg ground) or even a swapped ground and neutral (happens more than you think, even in new construction) then you'll get all sorts of changing ground loop currents, which can make hum come and go randomly. So by bonding all your grounds together from the various pwer circuits, you force these currents to occur inside the distro itself, and not via the shields of your snake or XLR cables. One thing you can do as an interesting experiment is to test for current using a standard clamp-ammeter around the entire feed wire, not splitting out the hot like a traditional test). Any current you read with this test will be the ground loop current you've diverted from your XLR interconnects.
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TJ (Tom) Cornish

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Re: Poor Man's Distro and Reverse Bootleg Ground situation?
« Reply #11 on: May 28, 2016, 07:30:09 am »

commercial coffee urn...
A large old church I do a lot of work in has coffee "urns" that are about 20 gallons, and conveniently the receptacle that powers them is a 14-50. :)
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Re: Poor Man's Distro and Reverse Bootleg Ground situation?
« Reply #11 on: May 28, 2016, 07:30:09 am »


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