So just bought a sp4 15 was wondering if anyone has done. 4th or 5th order with them and if they sound any good an opinions on boxes

I've heard 4 18" SP4s in a 4th order it sounded amazing.

www.bassheadsent.net for your 4th order designs.

That's a personal preference. Which roll off do you prefer.

Thanks ment to put 6th instead of 5th what really the differences if any

The 4th or 6th is the rate of roll of the enclosure has. It has nothing to do with style or "type" of enclosure. People normally prefer 4th order has a rolloff rate of 24db per octave.

The only reason to use a bandpass box over a ported enclosure is if you are restrained by space. You will almost always have a better response and be just as loud if not louder by going ported especially on the "lows" as a bandpass enclosure will normally start to rolloff relatively high compared to ported.

I have room in my trunk to make a 5 almost 6 foot cubic box (outside )would it be better to do just a ported or would I see a difference from the 4th I had a old single slug btl in and L port box and it slammed but was want to try different things thanks for all your help

Friend has a 6th order with 4 SP4 15's tuned to 50 and 30hz.. and its just NUTTY

I will be starting a build soon for a friend with a single 15in SP4 (trunk). After measuring and seeing what we want I can see it will be easier to do a standard ported firing forward sealed off from the rear. 4ish cuft net tuned low is what we are doing.

The 4th order needed 2cuft sealed section and 4-6ctft ported section and it was just too damn big after measuring unless alot of work was put into it.

A buddy told me to do a 2.1 ratio tuned to 47htz should I have port face trunk or face front on car car is 04grandprix with fold down seats

Maybe I understood it wrong, but Quentin said bandpass boxes can be smaller than normal ported boxes, and Swift said the opposite.

I've always thought bandpass boxes were huge, with 2 chambers.

I hear a lot of people talking about bandpass boxes, saying they are better, sound better, are louder,...etc

I'm lost.

Sorry for the threadjack, OP.

A buddy told me to do a 2.1 ratio tuned to 47htz should I have port face trunk or face front on car car is 04grandprix with fold down seats

Well your buddy doesn't know what he's talking about because there isn't any preset ratio to use. Every driver is different, and thus requires different alignments.

Maybe I understood it wrong, but Quentin said bandpass boxes can be smaller than normal ported boxes, and Swift said the opposite.

I've always thought bandpass boxes were huge, with 2 chambers.

I hear a lot of people talking about bandpass boxes, saying they are better, sound better, are louder,...etc

I'm lost.

Sorry for the threadjack, OP.

Maybe I have worded it wrong. You can typically cram a bandpass in a smaller area due to physical area of the way it can be positioned in the vehicle.

For example you could shoe horn a bandpass to go thru a ski hole but it might not be logical or possible to get a big ported box to work.

If you don't have the experience, I would suggest a standard 4th order vented, alot less to mess up...

I have 4 SP4 18's on 4 Crescendo bc3500's in a 4th order. It is pucking RETARDED. *drops mic & walks off stage

I have 4 SP4 18's on 4 Crescendo bc3500's in a 4th order. It is pucking RETARDED. *drops mic & walks off stage

I would love to hear it. I bet its just plain nasty!