I know it's a difficult picture, but you can just see the port tucked into the corner at the back of the box, with the woofer just above it. You can see how the two braces are kinda forming a little box around the port.

The two openings are approximately 8"x4.5" and 3.5"x16". There will also be light polyfill in the enclosure.

Whadda ya think?

Thanks!

Adam

Adam

The issue that concerns you, when having two chambers seperated by a restriction baffle, is that as frequency rises, the pressure source is increasingly more restricted to the second chamber. This creates an acoustic filter that becomes significant at some frequency depending on the dimensions of the constructs involved. It's a low-pass filter. That may or may not be a good thing, depending on what you expect from this design. At low frequencies, the filter function can be disregarded because static pressure will equalize between the two subchambers. Low frequency pressure changes act similarly to static pressures, and that's why you can disregard the filter function if the dimensions are large enough.

See the document called "Acoustic High-Pass, Low-Pass, and Band-Stop Filters", written by Daniel Russell for more information on this subject.

I just went ahead and finished the thing up with glue. There is a moderate amount of bracing inside the box, but it sure as hell does the job. The front panel (a large 2'x2' piece right behind the woofer) doesn't vibrate even in the slightest at up to and including max volume, so I'll toot my own horn and say I did a damn nice job of bracing :)

I also polyfilled the speaker and glued it up for good. That baby isn't coming apart. It has indeed added a quality to the response that I can't yet put my finger on; I'm too distracted by my damn suspended ceiling vibrating. Things are looking really excellent, though. I should have the CH-3's on friday, and from then on it's all down hill, for the first pair anyway.

By the way, I don't know what kind of subwoofers you may have in your house, but I ran this first glued and braced ten pi cabinet in conjunction with my normal home music sub (15" woofer 5 cubes tuning of 30 Hz) and I must say it really added warmth to the sound. The bottom fill coupled with the good midbass output from the ten pi (yes I know about the panels resonating, I'll fix it!) produced a lower few octaves that I can't say I've ever heard in a speaker before. I'm so impressed with it, that I'm thinking about purchasing four tempests (the drivers I mentioned a few days back) to augment the bottom end in the same way I did here. It really creates a sound I like a lot. I won't exactly be doing stadium concerts, so output from the four tempests shouldn't be any problem.

I urge you to give it a try! I think it sounded really nice.

Anyway, things are going smoothly.

Adam

While my current plan is still the expanding foam, I have a question for you. Would it be sufficient to use conventional bracing methods to make the reflector panels (or folds or whatever you want to call them) completely rigid, and then leave the backs of the speakers completely open? See, as it stands, my speakers have no top, bottom or back. As I see it, if you didn't enclose the rear of the thing, the chambers wouldn't act as resonators because the standing waves would simply dissipate into the room.

So with plenty of bracing on the reflector panels and simply leaving the back of the speaker exposed, could you sucessfully solve both problems? At the cost of looks of course... Just curious.

Adam

Adam