SPLChris

So....the compression chamber isn't really necessary if the sub has a strong motor? But how do you find out how large to make the chamber anyways? Duke, are those second enclosures line length the same as the first? What's the port area?

Kind of ironic that you made one of those, I had plans for a box with 1/4 wavelength "port." How did you figure how large to make the compressoin chamber?

They would work well in a 40 hz tapped horn That's what I planned on doing with mine but I don't have nearly enough room and I don't feel like making a folded design.

This is setup temporarily until I make another box. Still working on another 4th order I just wanted to see how this huge port performs. I posted a buildup of the port over on caraudio.com. It's 10.75" internal diameter and it flares out to 15.5 on the large flare and I don't remember the smaller flare. Finally got the electrical system where it needs to be...HO alt, 3 new batts, and new amp. Here's the pics! It moves a ton of air. Juice Box is an awesome song to play

Yes, helps a lot! Round ports are better than square ones anyway and some of the street guys have tested that a single larger port compared to 2 smaller ports has raised their score. This port has more area than three 6" and not to mention a very large flare but's it's pretty much impractical in any situation, though. There's no way I could make it fit internal unless I make the box really tall. This was just something I decided to do one day and it's worked out great. Got to do some more box mods and do some more testing. Thanks for the interest!

http://www.youtube.com/watch?v=Qc6uqrzyn7c http://www.youtube.com/watch?v=Z8qxFemUBWM Not the greatest. I should have done on on the driver side as that's where a lot of the air is swept. I was in a rush so I wouldn't aggrevate the neighbors so they aren't that great but there ya go!

On paper it's 5.5 cubes tuned to 40 but i think the frequency went down once I dropped it in the Jeep. It plays a lot lower and louder than I thought it would. It also helps to have 3+ kilowatts on tap

4th orders are WAAAAAY more forgiving than 6th orders and higher up and with that much space they aren't that more difficult than a ported enclosure. The front chamber is where you'll get all the efficiency, the larger the better. Your sealed section will determine your lower cutoff frequency and essentially how much power the subs can take. The larger the sealed section the lower it will play but at the expense of power handling. My 12's with the small sealed section sound AWESOME but I also don't listen to anything under 30 hz. With a ported wall that large, the subs will come close to the mechanical limits pretty quickly. With a 4th order, the sealed section will control the subs a lot better and you can reap the benefit of having a humongous port. A bandpass wall will destroy a ported wall. I would definitely consider it if I were you

With that much space, why not a bandpass? Put them in sealed boxes and have them fire into a loading wall. Make the port as big as possible then shrink to how it sounds best.

Don't post much here but I thought I would share my setup. I have my 2 SPL 12's in a 4th order bandpass in my Jeep Grand Cherokee. 1.3 cubes per sub on the rear chamber and the front chamber is 7.5 cubes tuned to 55 hz. I need to do some bracing or add a couple more layers but I couldn't wait to give it a listen. They are wired to .5 ohms on my American Bass XD1800 which does 2400 at .5 Since I'm not interested in sq, this setup is right up my ally. these things totally hammer and they aren't even close to getting RMS. They run out of steam around 30 hz (small sealed section) and the enclosure gives a huge peak at 40-50 hz. So far this is my favorite setup. They are so loud with the little power I'm giving them and I can't wait to give them 3000+ watts. This is a hell of a great street beat setup. Sorry for the lack of pictures. If anybody has a Jeep GC, I have no problem giving the dimensions of my box.

Yeah, it's hard to call them a "burp woofer" because they sound better than most comp subs but I got your point. It sucks about the TL since there isn't one close to where I live. A lot of the credit goes to the enclosure for the efficiency but they do well with even just a little over half of the are rated at. I'll try and get some pictures.