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Elect. Generator
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myprosound
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Joined: 30/07/2010 02:28:22
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i know this is not right place, but i saw so many experts here so i just take my chance

i will do a gig next week end outdoor

will be using 6 qsc k12 and 2 yorkville nx720s
what kind of generator (power) should i need?
if you know the model, make, please advise

Dale Christenson
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Joined: 29/07/2010 01:12:24
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Location: The great RED state of Oklahoma
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The experts here http://acapella.harmony-central.com/forumdisplay.php?s=&daysprune=&f=33 are much more suited to answer that type of a question. You may want to include all the equipment that will be on the genny down to any outboard gear.


member since 4-2009

This message was edited 1 time. Last update was at 30/07/2010 02:55:38

dale; a member of this forum since April 2009.
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PhilG
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that is a huge amount of power -

basically you want to allow for 9000w just for those speakers - plus any amps / external gear you will run

I would suggest something like a 10,000w generator with power filters attached - this way you will have some headroom

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rockstardave
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Joined: 29/07/2010 01:02:17
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double the required power. 15000 - 20000 watts
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kibo
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Joined: 28/07/2010 23:08:13
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Location: Toronto, Canada
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i think for the one k12s alone will require almost 300W. if it were a motor it will require maybe 3times or 4 times the power for start up. im not sure with amps. i think power requirement for the amps is different from RMS watts. i think to find the power requirement of an appliance, you will multiply the Amperage for the AC times the Voltage that you are using. k12s rates 2.3A on a 100V. so it only requires 230WAtts of power. more would be better of course.

thanks,

kibo

This message was edited 1 time. Last update was at 30/07/2010 06:35:16

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talmen
Presonoid
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Joined: 28/07/2010 23:56:13
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Add the amperage of all the connected gear, use that to figure the total wattage, leave probably at least 25-30% for headroom and to allow for general inefficiency of the generator-inverter system. You definitely want to have a system whose rating is significantly higher than the power you actually need. As far as I can see, about 10,000 Watts would give you plenty of room to breathe.
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jonelli
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Joined: 28/07/2010 22:58:53
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Location: Orange County
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Another place for professional advice is www.prosoundweb.com
I have nothing to do with the site, but the Live Audio Board (The LAB) has every audio industry professional there posting and sharing information.
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myprosound
Prenoob

Joined: 30/07/2010 02:28:22
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thank you all for inputs.
maybe i will get 2 Honda @ 6,500 watts each
Travis.falks
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Joined: 30/07/2010 22:22:16
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That might be a bad idea. The two generators would be out of phase with each other and likely cause some bad buzz, and maybe some equipment damage.
Then again, it may work just fine. Depends on a lot of factors.
myprosound
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Joined: 30/07/2010 02:28:22
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please explain more details of bad!
i was thinking that the K12 and the yorkvilles are powered speaker, therefore, i will run each generator on each side, independenly.

i will use 2 k12 for monitors and 4 k12 for foh along with 2 sub's

thanks

Travis.falks
Prenoob

Joined: 30/07/2010 22:22:16
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Ok, you've already proven you know more about generators that a lot of people I talk to. You'd be surprised how many people think they can just tie two generators to the same panel to get more power. I thought that's what you were talking about doing at first.
Now, as for running different parts of the system off separate generators, usually not a problem. Just make sure both generators are properly grounded. If not, any grounding issues will make their was into your audio cables.
I took a nasty shock just last week because of this. Foh was in no way grounded, but the racks back stage were. So naturally electricity follows the path of least resistance, which just happened to be pin 1 on the xlr's feeding the amps.
Just use a little common sense and you'll be fine out there.
MikeRivers
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Joined: 28/07/2010 15:44:52
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myprosound wrote:thank you all for inputs.
maybe i will get 2 Honda @ 6,500 watts each

Don't do that! unless you're going to use one for the lights and one for the sound. But really, you aren't looking at an unreasonable amount of power. The QSC K12 is rated at just a hair over 2A (240 VA), and the Yorkville NX720 spec sheet calls for 360 VA maximum. So that's a total of 6x240 + 2x360 = 2160 VA. Add in a couple hundred VA for a mixer and processing gear and a 3.5 kVA generator should handle it adequately. How about stage gear? Lights?

Is this something that you'll need all the time (like you're building a concert facility)? If not, just rent a single generator that has adequate power. At least with the rental places that we have around here, there isn't a lot of difference in price between a 5 and a 15 KVA generator of similar type, that is, well regulated and filtered, and noise-suppressed.

But I'll warn you that many generator rental outfits, particularly if they're delivering the generator rather than you going to pick it up yourself, is that they tend to give you what they have that meets your KVA requirement. Honda generators are generally pretty good, but make sure you get one for electronics, not a construction site generator or your sound system will sound like a Skil saw. Unless there's more than what you're telling us, one 6.5 kVA generator should be just fine.

It's a good idea to turn things on one at a time to avoid a heavy inrush load on the generator, and remember that if it runs out of gas or stalls for some other reason during the show, turn everything off, restart the generator, and then start turning the gear back on.
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myprosound
Prenoob

Joined: 30/07/2010 02:28:22
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thank you!
are you sure 1 Gen @ 6,500 is fine?

this is a small outdoor even (about 500 guests)

here is what i will bring:

6 k12
2 nx720s
1 sl24
1 dbx driverack 260
1 dbx driverack px
4 slx shure wilress mic's
2 keyboards

according to your calculation, the 6.5k w is good enough

the Honda unit i will rent is a new unit, it whisper motor,

the even will be @ 11am to 3pm so no lights needed.

thanks

Travis.falks
Prenoob

Joined: 30/07/2010 22:22:16
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Yea, I think you're right. The more I think about it the more I think there will be problems, even if the generators are tied to different parts of the system. It's still all tied together through the xlr cables. I didn't checks the specs on the gear, but it looks like mikerivers did, and his math looks pretty good... So if one 6.5k will do, then go with that. Don't risk a gig so something that "might work."
MikeRivers
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Joined: 28/07/2010 15:44:52
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myprosound wrote:thank you!
are you sure 1 Gen @ 6,500 is fine?

this is a small outdoor even (about 500 guests)

here is what i will bring:

6 k12
2 nx720s
1 sl24
1 dbx driverack 260
1 dbx driverack px
4 slx shure wilress mic's
2 keyboards

according to your calculation, the 6.5k w is good enough

I don't see any reason why it wouldn't be ample. The real power goes for the power amplifiers, and the Class D amplifiers used in the QSC speakers (and maybe in the Yorkvilles - I'm not sure about those) only draw current when they're working. The keyboards, mixer and processing gear are maybe 0.5 kVA at most.

Don't forget to get a gas can.
Visit http://mikeriversaudio.wordpress.com for some useful audio info
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