what will be louder, 3 15'' l7's or 4 12'' l7's?

im debating whether i should get 3 15" kicker L7's. or 4 12" kicker L7's. or maybe 3 rockford 15" p3's. most likely will be using sealed boxes because i like the sound quality with them.

Well, you can have 3,000w RMS @ 89.4db efficiency using the 15" L7's
... or you can have 3,000w RMW @ 88.6db efficiency with the 12" L7's
... of you can have 1,500w RMS @ 86.0db efficiency with the 15" p3's

This is based off the continuous power handling of the woofers, and their stated efficiency of 1watt/1meter. The three 15" L7's look loudest on paper, the four 12" L7's are really close, and the 15" p3's should be 1/4 as loud as the L7's, assuming you give them all 3,000w RMS. Wiring three woofers to get a 2ohm load is not easy, I'd use three monoblocks at 1kw each.

The difference between the 15" L7's and the 12" L7's is very little, and could be more influenced by the enclose you build. You could use one amp with the four woofers too, that's something to think about.

-Justin

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Malcom: "This is the captain. We have a...little problem with our engine sequence, so we may experience some slight turbulence and then...explode."
Jayne: "We're gonna explode? I don't wanna explode.

im not really a kicker fan, but i have heard the 15" L7 by itself in a ported box with a kicker amp. and man it was loud. i've had rockfords, 3 different type of 15's, older and newer models and i really liked them. but i really wanna be loud so i guess im gonna get the 15" L7's. i can get the dual 4 ohm ones and wire them to 8 ohms each and get a 2 ohm load on a mono amp. does this sound right? i know i would have to get a powerful amp to push these. the three mono amps sounds good but im already gonna have two more amps for my highs, so i dont want a lot of amps in the car. probably 3 the most. the 2 for my highs and one for my subs. i'll be running 4 6x9's in the rear deck and 4 6 1/2's in the front and 4 tweeters.

Not quite. You want the dual 2ohms woofers, and wire each woofer's voice coils in series to get two 4ohm woofers. Then wire those in parallel to get a 2ohm load for the amplifier.

Pure SPL is a concept I simply don't understand, but I hope you find what you're looking for.

-Justin

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Malcom: "This is the captain. We have a...little problem with our engine sequence, so we may experience some slight turbulence and then...explode."
Jayne: "We're gonna explode? I don't wanna explode.

i meant for 3 15" L7's with 4 ohm dvc.

Err, I misunderstood you. I was wiring for a pair of woofers, not three. If you use three, then yes you can get dual 4ohm coils in series for 8ohm woofers. Then put the three 8ohm woofers in parallel to get almost 2ohms to the amp. It will be 2 and 2/3rds ohms, but it's the best you can do with three woofers.

Try using these calculators.

-Justin

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Malcom: "This is the captain. We have a...little problem with our engine sequence, so we may experience some slight turbulence and then...explode."
Jayne: "We're gonna explode? I don't wanna explode.

cool, just wanted to make sure. i think i might go that route. thx.