I'm currently a University student and got into home audio video a little over a year ago. Since then I've put together a mediocre system. It consists of a Sony KP43T70, Panasonic A120, basic RCA 4head VCR, ExpressVu 4700 DSS, Onkyo TX-DS575, Klipsch KSB1.1 for mains and surrounds, Klipsch SC1 center, a Paradigm PDR10 and a One For All Cinema 6 Learning remote. The only piece I wasn't as content with as the others, was the sub. Don't get me wrong the PDR10 is a great little sub for it's price range, but it just always seemed to be straining during movies and heavy low bass in music. So while I was dreaming about getting Paradigm Active Reference and that new Outlaw Preamp, I decided a new sub would be feasible. So what should I get. Started looking around and posting to forums. Considering I'm in Canada I was seriously considering the Paradigm PW2200 which would have cost me between $900 and $950 CDN after taxes. Then in my posts on AVS this loud mouth arrogant SOB with a ridiculous number of posts informed me that I should build my own sub (by the way thanks Bob, and two of these things I built wasn't enough bass for you, GOOD GOD). It would cost half the PW2200 and blow it away. Needless to say I was skeptical, but he and some others pointed me to The Sonotube Links Page and the DIY forums on www.hometheaterforum.com and www.hometheatertalk.com. I then went through a couple weeks of reading and coming up with different design ideas. Oh and asking a lot of annoying question on the two above forums.

It was pretty easy to decide on either a Shiva or a Tempest considering the number of people on the forums using them, their low cost, and the ability to use LspCAD for free to design an enclosure using them. I was initially thinking of building a sub with as small of a box as I could. This meant considering an isobaric design using two Shiva's. I eventually decided that would be too complex and costly to try. The long port lengths (which could have been solved by passive radiators at even greater cost) and cost of two drivers just didn't make any sense for me. So then I decided, why not just make a bigger box and use a single Shiva. I then moved on to thinking about the Adire EBS alignment for the Shiva using slightly modified dimensions with an AVA250. Encouraged by my readings on the forums, I was enlightened to the virtues of big subs. I was showen the light again and decided what the hell, the Tempest is only $20 USD more, why not use it. I was still wanting a small box, but this time I decided I'd make the box as big as would fit where I was going to put it. I came up with what would have been about a 150L net volume box tuned to 17.5 Hz with a single flared 4" port. All looked good and I ordered the driver, amp and flared port kit. At the time I was pissed off, but luckily the AVA250 was on backorder (as it turned out for a month and a half). Over this agonizing waiting period I eventually came to the conclusion that if I'm going to build this thing I should do it as close to right as I could the first time. My limiting factor is the foot print, not height. With a Tempest I could get a rather small foot print if I used an 18" diameter Sonotube and just make it stupid tall in order to give the Tempest the volume it deserves. Which would also allow for a 6" diameter port to be used.

Having learnt a lot on the forums along with my driver and amp finally shipping (I cancelled the 4" flared port kit). I had decided on my final design:

Tempest powered by an AVA250
Net Volume = 260L using an 18.5" inner diameter Sonotube
6" port tuning it to 17hz
The endcaps would be 1.5" MDF
Port in center of top endcap
Driver in center of bottom endcap
Amp would be mounted to side of Sonotube in it's own small enclosure
Over all height approximately 5'11"

However, as Dr. Hyre of Adire audio pointed out this designed introduced one possible problem. The length the tube would need to be in order to get a net 260L volume would be the same as a half wave length of a 90-110hz sound wave (5' to 6' tube). There would be the possibility of standing waves forming in my tube. He also suggested that if I put insulation between the port the sonotube about a foot thick this shouldn't be a problem. As it would turn out he was correct. Go figure :p