BillFitzmaurice.info

CoronaOperator wrote:

NukePooch wrote: I ran it for a weekend gig on generator, and it just couldn't keep up, so I sent it back.

inukes and generators are a no go.

The inukes have no power factor correction: none, zero, nada.

This is largely true for most of the current Class D offerings. To say that you can't run them on a generator is a bit of a misstatement. You can't run them on a small construction generator alone. Those generators have autorev mechanisms that depend on current to activate. Put a couple of lights on them and they'll stay revved... but then you're using a significant part of the available current for the lights.

Class Ds work just fine on a properly sized commercial generator. As with anything, you have to do the math - since they gulp loads of power at once you just need a bigger generator and one that stays running all the time and can handle the load. If you have 10kw of Class D you probably need a 25-50kw generator to run them.

They take an 80 amp gulp of current, then sit around for awhile, then take another gulp.

Is this measured or speculated? Lets use the IPR2-7500 as an example. It's supposed to be able to deliver ~7500 watts across it's two channels and requires a 20A circuit to do that. Well.. that's 7500 watts at 2 ohms (which by the way is less stable than they'd like you to believe... the amp will cut out before it gets there, ask me how I know). That's ~60A at 120V. It won't "gulp" any more power than that. The NU12000 would have a maximum theoretical intake of 100 amps. That's 1/4 of the total power my house is wired for. Eh... probably not going to happen in real life. My real life experience with the IPR2-7500s is that four of them can run with a four ohm load on each channel off of a 2 20a circuits and have all channels tickling the limiters without blowing a breaker. I have done this on mains power and on commercial generators with no problems. They're going to get another workout this weekend in nearly ideal circumstances on a commercial generator. Not worried in the least.

I don't know what brand amplifiers we used on the big stage at a recent music festival (though FoH had a single Behringer in a rack for a medium stage).

Early in one of the big sets, a transient pushed the house amplifiers too hard, resulting in a 900 amp draw on a system rated for 600. Blew the breaker on the UPS system they were attached to. Of course, the fix was to mute house, power down all the amps, reset the breaker, and power up the amps one by one to prevent the inrush current from blowing the breaker again, then bring up house to a lower level.

The moral of the story? 150% of rated draw *isn't enough* with even the high end amps. =(

BrentEvans wrote: Is this measured or speculated?

Measured: http://forum.speakerplans.com/behringer ... 69202.html

Inuke NU-6000
80 amp gulps full power @ 4 ohms (1800 watts/channel rms)
50 amp gulps full power @ 8 ohms (1160 watts/channel rms)

The bottom purple trace is the current draw for the inukes: (each grey tick on the vertical axis is 10 amps)

Although the current draw over time is normal, look at those 80 amp peaks!!!

Ignore the wattage ratings on the box of ANY amplifier, those are ISL peak ratings. Look for the bench tests.

BrentEvans wrote: The NU12000 would have a maximum theoretical intake of 100 amps. That's 1/4 of the total power my house is wired for.

The NU12000 is 2 6000's together so you would be looking at over 160 amp peaks. These are intermittent peaks, not steady current draw.