I finally have the entire enclosure screwed together (once I find any errors and such it will be reassembled with full bracing and plenty of glue).

The thing is absolutely monsterous. It's just huge. I clearly underestimated the size of such a speaker, but as long as it sounds good I'm not too worried. They also way soooo much... there's nearly a sheet and a half of MDF in each box, plus woofer and compression driver plus other bracing when finished.

Firstly, I'm really concerned about excursion. The smaller box and lower tuning has actually resulted in what seems to be less power handling then the conventional bass reflex boxes that I've built for these woofers before. With only 120 or so watts applied the woofer was moving quite a bit. It could be an error in the box volume or tuning but I'm not sure. I had to displace about a half a cubic foot of volume from the design using some books because the HF horn isn't in place yet. Also, I had to move the port out of the box somewhat because it was too long to properly fit. The system sounds kind of chesty and the lower mids seem to resonate all over the place.

However, having said that I'm not sure if it's valid. There is no bracing in the box and there are a lot of vibrations. The two reflectors of the horn are resonating like mad and probably hurting the system by muddy'ing up response. There is as of yet no crossover on the woofer, so any response peaks above the crossover point are coming through loud and clear. There's also no high frequency, which is surely putting emphasis on the short comings of the system. There's no padding or stuffing in the box to even up frequency response and dissipate some of the midrange from the woofer. The internal box volume is probably incorrect. To boot, my listening room is the worst ever, with stupid rattling paneling and a suspended ceiling. These puppies belong in huge rooms or wide open spaces.

My *primary* concern right now is the excursion. There is no way this woofer will handle even close to 400 watts at present excursion, which is dissapointing because in 5 cubes tuned to 40 Hz it will. This is my main worry right now and the only thing that can't be explained. I'm hoping wayne can put my mind to ease about this.

Anyway I shall post a picture in about a half hour!!!

Any input from anybody?

Thanks. Hopefully I'll hear from you Wayne.

Adam

Adam

I should tell you exactly what I did... PIALIGN recommended an overall horn size to me that was within an inch or two of 24"x24"x48", I just fudged the numbers a bit to fit that which is fine. Pi Align *also* recommended a 2.2 cuft ported chamber which it said was like 10"x17"x23" or something like that. Now, when I apply the 24"x24"x48" recommended horn size into the ratios in the plan, the result is a ported enclosure that is 8" deep, 16" high and 24" wide, which is *different* then what PIALIGN gives me. This chamber is only 1.77 cuft in internal volume. After factoring in about 0.4 cubes of displacement for the woofer, 0.4 cubes for the horn lense and compression driver plus a bit of extra for bracing and port, the result is a 0.77 cuft enclosure for the woofer, which is wayyyy too small! The only thing the top chamber does is compensate for these two descrepancies by adding an additional 1.4 cuft of box volume, to bring things up to the desired 2.2.

I currently have about a .5 cuft of old books inside the box to displace the volume that the compression driver lense would normally take up. Unless I made a signifigant design error, the overall horn size that PIALIGN gave me is correct as is the internal box volume and tuning. It's actually more correct then if I had made the entire design bigger (increase box volume without the extension and thereby increase the proportions of the bass horn).

Anyway, I'm not a bit surprised about the other things and I'm glad they'll be cleared up. Right now I can't afford all that hardening foam, so I am going to attempt to use some conventional bracing on the two reflector panels... But I doubt it'll work. If it would, I suppose you would have done it that way! :)

Anyway that's the story on the enclosure volume, I hope you can provide some input. I know I didn't mention the descrepancy between what PIALIGN told me and what the ratio plan was telling me, but I felt I had asked enough questions of you for the time being and didn't want to be a bother.

Thanks!

Adam

Adam