Power Amps, Speakers, and Crossovers...for live sound?

[sjaguar13]

I am confused about how to hook up some speakers for live sound. I have 2 cabinets with a 15 and a horn, and then 2 other cabinets with 12s and a horn. I want the 15 for the low end, and the 12s for the higher end. My plan was to get a crossover and hook it up to one of each cab. Is the horn in the 15 cab going to cause problems, or will it more than likely do nothing since the higher end stuff is going to the horn in the 12s cab? Is there a better way to use both cabinets? Should I just hook all of them up as the mains and screw the crossover?

Next question is, how do I power them all? If each cabinet is 1,400 watts, do I get a 1,400 watt power amp for each speaker, or one for each pair of speakers since the amps have two channels? Do I get 4 amps or 2? If I get 2, do I use the one amp for both 15 cabs and the other for both 12s, or do I use one amp for the speakers on the left side and the other for the speakers on the right?

[mixsit]

If the speakers are both full range and similar sounding why not just run them as is -unless you're going to break them down and scrap existing designs? ...assuming they're already a working system.

[sjaguar13]

That's what I would like to do, just run them the way they are. The issue is, what about the amps? If I need 4 amps, one for each speaker, then I will run into an issue without output jacks off the mixer.

The mixer has 2 mains, and 4 aux sends. If I use a crossover, that lets me use both both sets of speakers with the main outputs. Then I can use 4 floor monitors with the aux sends. If I can use 1 amp to power two speakers, I can still use the main outputs for both sets of speakers, and then 2 aux sends for a pair of floor monitors.

Basically, I need to figure out how many power amps I need, four or eight.

[dementedchord]

you're making this way more confusing than it needs to be.... theorehticlly you could drive them all with a single amp.... it would need to be one hell of an amp but there it is.... on apracticle level though you'ld probably need 2 channels with 2 cabs on each side... i'm assuming that the cabs are 8ohm abd the amp can handle a 4 ohm load (most can) as to how much power??? depends on the speakers... size of the room... what realisticcly are you expecting for levels... what are the power handling capabilities of the speakers??? is that in RMS?peak power?? music power???? ISBL??? all these things are considerations so we'll need more data....

BTW if you're not familiar with the ISBL power rateing dont worry... i made it up while working in audio retail... and applied it to all those seemingly impossible rated systems you see advertized... it stands for "If Struck By Lightening" and yes for that brief moment before it blows it might actually put out a gazzillion watts....

[sjaguar13]

I read a few things, and this is what I get confused by. Some things say a 1,400 speaker can take up to 1,400 watts. Other things say the speaker needs at least 1,400 to operate otherwise it will be under powered and over strained.

The 15" cab is actually 1,000 watts peak, 500 watts RMS. The other is 1,400 watts peak, 700 RMS. The amp just says total power 1,400 watts.

Think one amp could power one of each cabinet?

[dementedchord]

the RMS# is the important one... 500-700 are pretty hefty... what kind of music??? what size rooms???? real loud??? it's not unusual for the amp to be rated more than the speakers... although somewhat misunderstood the reason is often it's the distortion that blows a speaker... so a lower power amp though it sounds pretty much as loud will distort more because it's working too hard... oversimplified...

[mixsit]

Originally Posted by sjaguar13

...The 15" cab is actually 1,000 watts peak, 500 watts RMS. The other is 1,400 watts peak, 700 RMS.

500 -700, just wondering what speakers these are?