Question about active crossovers and multiple amplifiers

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If I were to use a stereo set of speakers with 2 way active crossovers and a subwoofer with an active crossover as well, how exactly do you split the audio signal so that it goes to all the amplifiers? Do you just use a preamp or something? Any help is greatly appreciated. Sorry if I am just asking a stupid question.

There is some great information on biamping and triamping at Rod Elliott's site:
He's also got crossover projects.

For the subwoofer, I assume you mean you want a single subwoofer to cover both channels? You can sum the Left and Right crossover subwoofer outputs using an op-amp summer circuit.
So: feed the preamp output to the crossovers, feed the high and mid crossover outputs to your stereo amps, and sum the low crossover outputs and feed it to the subwoofer amp.
I think that's what you were asking...
yea, that's what I meant. Thanks. I was looking around on the site you mentioned and noticed the kits for the amplifier as well as the active crossover. I am trying to set up a dj/sound reinforcement setup without spending a ton of cash. My question is, do you think it would be better to buy the amplifier kit or just pick up a really cheap older integrated amplifier off of ebay or something? I'm not extremely worried about sound quality, although I do want it to sound good, but more about high volume levels for extended amounts of time. If you have built the kit or know anyone who has, could you give me a rough total price? Any help would be appreciated. Thanks.

Note Rod doesn't sell kits, just circuit boards. You'd have to acquire the parts, cabinet, etc. yourself. That makes it tough to estimate prices.
I like the progressive upgrade approach - do what you can afford for now (maybe skip the sub?). If there's an opportunity to pick up a good used amp, go for it - note from what Rod says, using biamping makes amps better because you're limiting their bandwidth.
Then you can start to improve things. Who knows, you might end up with a water-cooled, quad-amped system like GRollins has?
Then again, I doubt most DJ's have 12, 12 inch subs like Grey does...

I think that if you want to save money, just pick up an older, powerful amp off of e-bay. They can often be found in abundance there. Plus, if you want high wattages, you don't have to worry about heat sinking and such. Also, if you can get your hands on the schematics, you can just upgrade the parts and internal wiring if you want to increase the sound quality. Also, if you need to connect 2 amps from only a single output jack, you can use a Y-cable, which is basically a single rca plug, which is split off into two more RCA plugs (or whatever your connector type may be)
Given that you're shooting for DJ-type stuff, I'd recommend that you shoot for pro gear, rather than hifi. Look for Crest or QSC or whatever is hot this year, perhaps used, if you want to save money. No, the fidelity won't be as high, but you'll get a lot more wattage, it'll weigh a lot less, and it'll be more reliable for your intended use.
Unless you can find a couple of ex-linebacker critters to do your heavy lifting, I'd advise against the 12x12" route. These subs weigh well over 300 pounds per channel. It's as much as I can do to move the blasted things.
(Oh, how we suffer for our art...)

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