Running a PA on a power inverter?

[rmila00]

Will a power inverter with a modified sine wave output run a PA system? Does any one know?
Does the power inverter have clean enough power to use with PA equpiment without making a ton of noise in the sound.
Thanks

[workingfire]

Depends on the size of the PA, the size of the inverter, and the power source.

[Craigv]

I've seen Xantrex MSW units used successfully. They do this at Disney World for some of the roaming bands in the parks....cart with batteries, inverter and amp/speaker.

[agedhorse]

Yes, but as Craig mentions there is a lot of "it all depends" involved.

I used to run a pretty substantial PA off of a solar system w/ a forklift deep cycle battery (about 2000 lbs) and a 7500 watt sine wave inverter. Not for the faint of technical skills though.

[kevinnem]

I would also consider that you may want to add a cap between the batery and teh inverter, to smooth out any big draws from the inverter. Also , I am not sure I would run it off a engine, as you could fry the alternator. I would go batery , or generator or both.

[TexasJim]

What they all said, plus: My inverter puts out a LOT of RF noise. The further away from it your stuff is, the better. If I run guitar amp off mine within about fifteen feet, I have a constant high pitch buzz.

Good Luck!

Texas Jim

[agedhorse]

The Trace Engineering inverters were pretty quiet. Also not cheap!!!

[Craigv]

I have to correct myself here.....just happened to be browsing the West Marine catalog and saw the inverters used at Disney....they're not MSW. They were Xantrex Prosine units, which run between 1000 and 3000 watts, and $800-$3000. They produce a pure sine wave, not stepped as with True Sine Wave inverters. They are UL and CSA approved. The more expensive models have built in battery chargers, which may or may not be an issue depending on your actual use.

[agedhorse]

I believe ther are all stepped, but the "true" sine wave inverters use high frequency PWM and then a reconstruction filter to look a lot like a sine wave. It's a class D equivelant actually.

[boseengineer]

.... which makes them not a great fit for class D amplifiers, since you have two switchers in a row. Peak current requirements are higher for class D amps.

[Craigv]

Originally posted by agedhorse
I believe ther are all stepped, but the "true" sine wave inverters use high frequency PWM and then a reconstruction filter to look a lot like a sine wave. It's a class D equivelant actually.

West Marine seems to differentiate MSW, TSW and PSW. The better TSW units spec 45-70 steps per sine, but they don't mention anything on the Pure Sine Wave uints, so maybe they're a smooth contour?

[agedhorse]

The output signal passes through an integration low pass filter (big ol' choke and maybe a cap) to smooth things out.