The Beginning...

On July 10th 2007 I began making a personal addition to my home theatre's sound system - 80 days later I completed it: the world's first Rubik's Cube subwoofer...

In case you are unfamiliar with subwoofer construction, Brian Steele runs a great site - the DIY Subwoofer Page. On it, you'll find advice, calculations, templates, and examples of those who have dared before you. Since there are literally hundreds of sites, software programs, and books on the subject matter I’ll summarize my final specs below:

Sealed Enclosure: 3 Cu. Feet
Driver Diameter: 15", Aluminum Cone
Outer Enclosure: 3/4" MDF Shell with 3/4" MDF 'tiles' overlaying it, forming the Rubik's Squares
Reinforcement: 1 Y/Z-Axis piece of 3/4" MDF, cut to allow driver. 1 X/Y-Axis piece of 3/4" MDF, cut to allow driver and Plate Amp. 1 Z-Axis piece of 3/4" MDF, cut to allow Driver. 1 full piece of 1/2" MDF at top. 1 Cut piece of 3/4" MDF on bottom.
Total Box measurements: 20.75" Wide, 20.75" Tall, 20.75" Long
Tile size: Face: 7.5" X 7.5", Cube: 7.5" X 7.5" X 7.5"
Total Measurements: 22.5" Wide, 25.5" Tall (w/ 3" feet), 22.5" Long
Total Weight w/o Speaker, wiring, Poly-fil, Amplifier: ~98 lbs.
Total Weight: ~144 lbs.

It's a beast, I must say, but before we begin how about some background information? My current system utilizes 2 Paradigm v3.0 Studio 100s (fronts), 1 CC-590 center, and 2 Studio 20s for 5.1 surrounds. Driving all that is an NAD T773, biamped with 2 NAD C272s for the fronts and discrete 7.1 inputs biamping the 20s - Long live the Canadian sound! Likewise, when I finally moved into my new apartment with space for a television (that's a luxury in Boston) I wanted the extra kick for DVDs - what HT is complete without a sub? I'll admit I’m a bit of a purest and can’t stomach the thought of attaching an external sub to my stereo so my search began for something that could rock the 60hz range in movies but neither force me to rewire every time I want to play a CD...

Being a huge fan of my Paradigms, I naturally went to the accompanying model for my Studio 100s - the Direct Servo 15. Despite making a great sub, I also played around with the option I eventually went with - making one. Reasons for this were two-fold - I hadn't taken on any art pieces in a while and just having dropped first, last, security, etc for the new place I didn't want to make a large purchase (insert your Alanis Joke here). Long story short, I chose to go with a Rythmik Audio Servo-15. One visit to Rythmik Audio's website and you can see that these guys aren’t messing around.

If you're completely new to building (Hi Mom!), here's what you need to know in order to make sense of the pics below: A sealed Sub system (this one) is comprised of air-tight box, a large (usually 8" or more) driver and an amplifier to power it. The driver vibrates the air inside the box which causes low-end sound waves to form. Since the box is being shaken so violently it is extremely important that box be very well braced - as in you should be able to stand on it and jump - it should also be heavy enough that it doesn't move. The interior size of the box is a carefully calculated volume of air that must be present along with the interior support.

So, after 2 weeks of drawing up plans, I finalized my measurements and got started...
The ceremonial first picture. I can't emphasize this enough: work everything out on paper first - the yellow pad there is full of calculations that I referenced every step of the way. Also I’ll take this time to mention I built this in my old (rented) apartment, the space you see here is my landlord’s basement, haha.

My design calls for the outer 3/4" MDF to overlap in certain places and underlap in others. I'm using all butt-joints and reinforcing the bottom with a second layer of 3/4" MDF and the top with an additional 1/2" sheet of MDF. The pieces have been marked for easy reference. Notice on the first piece you'll see '.5' corresponding to my 1/2" MDF and next to that 19.25" X 19.25". This corresponds to the outer 3/4" MDF in which the .5" sits - my original calculations called for a total size of (19.25x19.25+.75+.75) 20.75" X/Y/Z for .25" thickness overhang (from the Rubik’s tiles) surrounding the shell. This design was changed in tiling stage and I'll explain why below!

The interior braces of the box, I’m reinforcing on all 3 axis, the cuts and holes you see drawn are for amp/driver displacement, but more importantly air displacement.


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