Been running 5.25" studio monitors without a sub for a while. Have a 18" sub on 1200 watts in my car, so my need for bass was pretty great. Decided to use an old Onkyo HTIB passive HT sub I had sitting around to make it a 2.1 setup.
Tore out the old aero port, which after calculations in a box design calculator had the box tuned to 55hz ?!?! Like what the **** kind of tuning is that. And my math was not wrong, trust me.
Bought a 2" aeroport, custom cut it to the required length for my desired tuning and glued it all together. It's flared on both ends, inside of the box and obviously out. The box is now tuned to 33hz. Still using the stock 8" sub, it is MUCH louder than before. And it's only being pushed by a 100 watt old JVC plate amp I took out of an old sub. No port noise either which was a big problem with the old one. Damn thing was a 4" port.
Box is a little tore up now and you can see slight excess dried glue. I'll clean it up eventually and want to wrap the box in vinyl or something better looking.
Warning: Spoiler! (Click to show)
I have a new sub coming for the box Tuesday, the one that all the calculations were based off, including displacement. It's a Sundown Audio E8v3. Should be plenty loud for my room setup. Hopefully it fits without any issues. Based on measurements it should.
Works out to 0.76cuft^3. I believe it's 0.01 above recommended, but after I buy a new plate amp and install it in the box, it'll displace enough to make it within, though I'm sure it'll sound perfectly fine.
Warning: Spoiler! (Click to show)
Funny I'm using an 8" as my sub though when I have this sitting in my room too

It's a Sundown Audio Zv.2 18" in a 6.5cuft^3 box tuned to 32hz. Designed the box myself, built with a friend. It's his sub, just holding it for him as it's being sold. For anyone who knows sundown, the sub has been upgraded with all Zv.3 parts. Was around $160 I think for the upgrades.
Of course I hooked it up to my little plate amp just to listen to it for laughs, and it's loud as expected. I used to run an 18" sub in my room before, but now it's in my car instead. Subs these loud are for when no one is home, so I'll stick with my new 8" when it comes.
Edited by hatrix216 - 3/30/13 at 10:14pm