Steve and David:
Q: How much PA for 1000 people?
A: A lot!
Even if you pack them in tight, your room has to be pretty big just to hold them all. Say 100 ft X 100 ft?
Would you settle for an spl of 90 dB in the middle of the room? (84 at the back) For the system from Carvin, the speakers claim an output of 103dB SPL. Not going to cut it. You're going to need at least 114 dB at 3 feet.(Best case - SPL goes down 6dB every time you double the distance from the speaker) Not very loud still, but hey - if they don't like it they can leave, right?
The speakers in that system are 4 Ohms. The specs on the amp are only 700W per channel at 4 Ohms. Slightly underpowered, but ok.
So - add another pair of speakers. (+$600) Now you've got only 350W of power per speaker - dangerous territory there and certainly not enough power to get the volume up where you want it with those three way cabs.
Ok, so add another amplifier (+$600) Good - now you have an extra 6dB to work with. Still not enough. But maybe it'll be ok for now.
And this is supposed to be rock'n'roll? Where's the bass thump? subs and another amp from Carvin. (+$1600) Well, it's not exactly chest thumping, but at least I can hear the bass drum now.
Hmm - got it set up, but it sounds like crap - all this high-end cancellation going on - wonder what's up with that? Another look at the specs, and you see that the speakers have a 90 x 45 dispersion. Can't just plop two of them down side by side like that. And once everyone's in the room, I can't hear anything at the back. Better get them up off the ground so that the people in front aren't blocking all the sounds with their tightly packed together bodies. OK - put them up on the stage . . . Geez these things are heavy - 124 lbs! Times 4. And I wish I had a decent eq so I could notch out some of these feedback frequencies. And damn, my mixer just tumbled down the stairs with the kid who's helping tear down tonight - wish I'd bought that road case.
Have I made my point yet? Can you see where this is going?
I realize this sounds sarcastic and bitchy. My point was not to make fun of you, or demean you. I'm just trying to get it through to you that you've already received a lot of very good advice here. There is a lot more to all of this than meets the eye, and even if your doubled budget is approved, you have the bare minimum for a shoddy MI quality system that will not quite provide the level of power you need, and won't sound very good.
Sure, you can do it. And you'll learn a lot from it. But there are other ways to learn than making mistakes.
Added Disclaimer: I've greatly simplified things as far as SPL calculations go, and what you'll get out of this system. I think i've been rather optimistic realy