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Old 05-19-2009, 04:29 AM   #1
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Amplifiers running off generator


I have two 900 watt Peavey amplifiers with two Bose Pro Series Mach II full range speakers, a Stanton dual deck mixer, a HP Pavillion laptop computer and a small work light on my DJ set up. The event scheduled for this weekend is being powered by a Honda 5000 watt gasoline generator. Can I run my set up without harming anything? Should I ground the generator from the grounding post? What about the dummy load issue on start up? I run each side of stereo (right and left) off one P900 in bridge mode; too much for the genni?

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Old 05-19-2009, 10:43 AM   #2
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Amplifiers running off generator


Here is what the power looks like coming from various back-up devices and generators...

http://www.jkovach.net/projects/powerquality/

To get perfectly clean power, get a "pure sine wave" "online" ups. Pure sine wave means perfect power. Online means that the UPS is ALWAYS making the electricity provided to the outlets - power on or back-up.

Other UPS only make the electricity in back-up mode when the power is off.

Here is a google search of pure sine wave online ups...
http://www.google.com/search?hl=en&s...ps&btnG=Search

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Old 05-19-2009, 11:38 AM   #3
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Amplifiers running off generator


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Originally Posted by KNO1962 View Post
I have two 900 watt Peavey amplifiers
is being powered by a Honda 5000 watt gasoline generator.
Class B amplifiers are ~80% efficient so your peak amp power input might be 2x900x5/4 = 2300w or a little more. Should be fine.

Don't forget ear protection.

Last edited by Yoyizit; 05-19-2009 at 11:52 AM.
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Old 05-19-2009, 12:53 PM   #4
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Amplifiers running off generator


Ewwww, Peavey? You must not DJ a lot of "gigs".

If this generator is soley for your power only, you should be ok, if its being shared with other things at the event, you could possibly run into problems with having enough power.

The only thing I can think of possibly having an issue is the laptop. You may get a buzz in the sound system with the laptop plugged into the generator power. I have noticed the issue especially prevalant when using a power inverter. If you have a computer UPS you can plug the smaller power draw items into (laptop, mixer, dj decks, etc) that would be best. If you experience any ground loop issues or a 60hz buzz/hum in the system, try lifting pin1 on the xlr's to the amps (or if its 1/4" lift the sheild). I have seen where people have used a 2 prong to 3 prong adaptor to lift the ground on the equipment, DO NOT ATTEMPT THIS! Lift the ground on the signal cable only if yoou need to.

The sound and lighting company I work for has used the 5000 watt generators with power amps in the past with no issues, its nice when you run 20 speakers down a road a mile and a half long and don't have to worry about ground loops with generators and wireless transmission at each road block.
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Old 05-19-2009, 01:41 PM   #5
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Amplifiers running off generator


Disconnecting the shield on 1/4inch is kind of iffy. On XLR it's fine because it's a balanced signal which doesn't even really need a ground, but on 1/4th you are forcing your signal to go over your electrical ground if you break the signal ground. It might work in a pinch but it could easily make things worse and cause some hard to troubleshoot issues and unexpected failures (unplug the power on something random and you lose your mics).
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Old 05-19-2009, 06:07 PM   #6
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Amplifiers running off generator


Quote:
Originally Posted by Gigs View Post
Disconnecting the shield on 1/4inch is kind of iffy. On XLR it's fine because it's a balanced signal which doesn't even really need a ground, but on 1/4th you are forcing your signal to go over your electrical ground if you break the signal ground. It might work in a pinch but it could easily make things worse and cause some hard to troubleshoot issues and unexpected failures (unplug the power on something random and you lose your mics).
I was thinking of balanced 1/4", sorry I don't use unbalanced cables to my power amps, I didn't even think of that scenario.

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