I came across an old Adire Brahma 15", 4ohm total subwoofer driver on Craigslist for $100. At $100 I figured it would be a fun driver to play with. This teenager had it in the trunk of his mustang in a really nicely done, sealed 2.5sqr ft box so it seemed a good deal.
First, I am spectacularly happy with my Shiva X, 10sqr ft cabinet, and Behringer EP combo (there are a bunch of people with exactly the same set up so you are a familiar with it). So I am not looking for a replacement home theater sub. So I threw the Brahma 15" in my unfinished Shiva test cabinet that was 9.5ft with the crude bracing and hooked up the Behringer……WHOA! The Brahma is loud as hell! BUT!!! I can’t hide TWO enclosures this size in my living due to wife constraints. Not to mention my Shiva cabinet is already finished very nicely.
So I slapped it back in the sealed 2.5ft enclosure it came in. I then cut a hole in back of the box and installed my unused MCM 300watt plate amp with an Elemental Designs sub eq on top. Finally, I finished it off with some decorate wooden legs to make it look more “Home” audio oriented. It sounds surprisingly nice in this set up. With room re-enforcement and a 20hz eq bump it sounds much better than it modeled. In fact, it is surprisingly loud for its footprint (not Shiva loud at 20Hz of course
Now I did upgrade the MCM amp's power supply by replacing the 2 x 6800uF 80vlt caps with a bank of 4 x 8200uf 80vlt caps (and beefier rectifier to charge them) I had left over just to keep it in line with the whole 10,000uF per 100watt general rule of thumb. But it is still only 300watts so I am only using roughly half the Brahma's capable Xmax according to model.
The cabinet is ¾” MDF and internals are 15.5”x15.5”x21” – minus driver volume, stuffed with 2lbs of acoustic fill and has NO internal bracing. I don’t think I can spare much airspace plus it is fun to have a small foot print sub project that I don't have to fill the garage with sawdust again to play with.
QUESTION: So should I add bracing since I am not putting a butt-load of power to it? If so, how much bracing should I add for such a small wall area? I also have a 4’x 5’ x 1/8” sheet of lead I could cut and glue to the interior walls to bring down the resonant frequency instead of bracing the walls. I am curious to the expert and not so experts forum. thoughts