If you saw my other thread on this topic (link) you would know that I'm trying to help my parents install a 5.1 system since they are renovating their house. I was having trouble with sub design/placement options because they are very picky customers. I was inspired by joorge's post in my thread about the parts express "boogieman" sub. I came up with something that I think will work decently well. It won't shake the house down by any stretch, but they are not audiophiles and they have hardly given much to work with.
We settled on a small space in a wall that is centrally located in the large open room. This space is about 10" wide, 11" deep and 36" tall. I plan to build a ported box to take advantage of every cubic inch they will give me. The whole thing will be flushed in the wall and finished with a cloth grill. This is not a large space, so my choices are very limited. I have selected a tang band 8" (link) from PE. I'll use two of them and a 30" folded slot port to give me a box tune of about 29Hz. This driver has great power handling, Xmax and a small VAS, which was key to this design. I'll top it off with a 500 watt BASH plate amp, but it will be running only 250W because the drivers will be wired in series for an 8ohm load.
Small problem. If I extend the port the additional length to get 27Hz tune, the end gets too close to the center brace. I would have to keep 29, which isn't bad or extend the port to about 39 inches total length so that it ends at the brace. That is getting too long and port resonance could come into play. I could also reduce the port cross section, which would reduce the length requirement for a given tune. The question is, what are the dimensional limits on a slotted port. It is currently 8.5 x 1.5, if I go down to 1.25, my port length goes down to 31.25" and my port air speed is about 13m/s. I think I'd be good and I get the added benefit of some extra effective volume. I just don't know if that is too thin for the slot. Any help?
With a 29 hz tuning a 8.5 x 1.5 slot port is 32.5 inches long. With a HPF at 24.3 hz and the boost that goes with it and 500 watts input power the port air speed is 32 m/s at 29 hz, definitely at the limits. I'm not sure how you're coming up with 13m/s.
I'm using Unibox right now, but I'll download WinISD and double check. I'm modeling with two drivers at 250W total input power. This is what I get. Of course this doesn't account for frequency response of the amp itself.
I guess nothing is settled until it's built....right? In an effort to reduce port air speed, I've tweaked it more. Box volume 31l, tune to 28Hz, port dims: 1.375 x 8.5. Response changes marginally, port is a few inches longer, air speed drops to 20.5m/s.
Very professional-looking work so far! :clap: I also like the design although I would have built a [email protected] rear loaded horn with those drivers hsd: :dumbcrazy, but I guess that would be kind of a overkill.
Thanks! Yeah, it is a 1 1/4 round over bit, but I only cut it to 1 1/8 depth. I wanted to keep that slight edge on the face instead of driving the radius down flush with the front face. I was out of town this past weekend, so I hadn't made much progress. Also, I only glue and clamp one piece on at a time. A lot of guys will just throw it all together and tack it with nails or screws to hold it while it dries. I should get finished pictures up this weekend.