Subwoofer Enclosure/Amp Rack

I used a prefab SubZone enclosure & a/d/s/ 310rs.2 subwoofer in my first install in the TT. It sounded excellent, but it wasn't great to look at:

After educating myself on fabricating with fiberglass, I decided to take the plunge. I went with two 10" Image Dynamics IDQ10 D2 V.2s instead of a single 10" sub for a few reasons: 1) I've always had dual sub setups until my first system in the TT, and I believe they sound more balanced throughout the cabin, 2) with equal amplifer power I should get more volume from two subs with better response, 3) dual configuration is more symmetrical to design & view. I chose IDQs because: 1) I needed to show my a/d/s/ PH15.2 a 4-Ohm load on all channels, and 2) they perform well in small enclosures. Okay, time to get to the good stuff . . .

Highlights:
--> fiberglass & 3/4" MDF construction (fiberglass contoured along floor, outside "walls," and rear);
--> two 10" Image Dynamics IDQ v.2s;
--> each subwoofer gets over .40 ft3 of internal (sealed) volume in individual enclosures;
--> a/d/s/ PH 15.2 amplifier;
--> locked to chassis, but easily removable for full access to jack and spare;
--> absolutely no cutting or modification to the car whatsoever;
--> takes up VERY little trunk space (more than enough room for a medium suitcase & more!).

Framing
Planning to utilize the space in those "pockets" in the hatch rear:

Arranging where the two 10" Image Dynamics IDQ10 D2 V.2s and PH15.2 are going:

After measuring.40 ft3 of packing peanuts in a box, it was time to see how everything would fit in the TT:

Cutting and positioning of cardboard templates:

Measuring and cutting Lightweight 3/4" MDF:

Pre-drilling and countersinking for the drywall screws:

Wood glue before screws:

Taking shape:

First test fitting of frame:

Get screwed!:

After using the router and the sander, finally a nice, compound curve to match the interior:

Using a 15-year old router, a new bit, and a homemade (MDF) circle jig to make perfect circles (along with a countersunk inner edge to recess the sub basket):

Another test fit:

Test fitting the IDQ . . . perfect fit . . . good, I didn't want to do that again:

Another test fit:

Countersinking and pre-drilling for the drywall screws:

Assembling:

Test fit with hatch closed:

Masking
Tape helps align everything as you glass:

Overlapping tape means no leakage:

Any resin leakage would ruin the interior, so add that next layer:

Finished with plastic sheeting for total protection:

Glassing
Materials ready to go: Knytex cloth, mat, roller, epoxy resin, and hardener all from U.S. Composites, Inc.:

Layer two underway:

View from the front:

Closeup of rear corner (epoxy resin is great--it bonds with MDF very well, and is low in odor unlike polyester resin):

Getting closer to being done:

After "popping" the mold:

Test fit . . . fits like a glove:

With the addition of the top glassed-in & amp rack:

Plenty-o-room for a medium suitcase & then some:

Finishing
After 1) filling all screw holes and gaps with Bondo and wood filler, and 2) sanding for a long time, it's finally ready to take a finish (notice the amp rack covers, too):

Masked & applying flat black paint to the inner sub rings & amp rack (& almost everywhere else, too):

Duplicolor truck bed liner coating for the enclosure surface (when dried, matches the hatch area's black plastic):

After applying the second coat of Duplicolor. Notice the radiused edge:

Duplicoloring the uper & lower amp rack covers:

While that dries, it's a good time to solder the IDQs so that each driver shows the PH15.2 a 4-Ohm load:

Done Duplicoloring:

Using 100% silicone to prevent air leaks from the enclosures:

I used high-strength magnets to secure the amp covers to the amp rack area--perfect for a clean look:

Polyfill--a small, sealed enclosure's best friend:

Using rope caulk to seal the IDQ's basket to the enclosure:

IDQ mounted. Notice, too, the accessibility of the amp's connections & switches:

One IDQ to go:

Notice the reveal I chose on the IDQs & PH15.2--just enough to be interesting (I hope) to look at:

Something I never planned on or noticed until after installing the amp--the colors on the Image Dynamics IDQ & a/d/s/ PH15.2 are the same (despite being built 12+ years apart)!:

Getting ready to get this thing hooked up:

Everything (12v, ground, remote turn on, signal, speaker wire) is connected using breakaway connectors in the event I need access to the spare tire. The 12v & ground for the amp are critical, so I used these beefy connectors from Parts Express--they're great:

The enclosure fits so snugly that it doesn't move at all side-to-side. I keep it from moving front-to-back by wrapping web rope around the jack holder assembly (fastened in with bolts to the car body) and through the U-bolt I installed on the enclosure:

In the above picture you can see a (modified) red LED bar that I mounted to the upper amp rack cover. I began by running a fused lead from the yellow switched buss terminal under the driver's-side dash (this way it'll only light up if the ignition is on):

Here is the stock cupholder assembly removed. I ran 12v power through the transmission tunnel area to the cupholder, where I removed a blank that housed the phone plug if I had ordered the TT with the (analog) phone option. I installed a rocker switch here for the LEDs so I can turn them on when I wish--perfect fit, looks stock:

Here the LEDs are switched on:

Fitted into the TT (Two 8.5"x11" sheets of paper in there for scale):

Page 1 = Intro
Page 2 = Head Unit & Amplifier
Page 3 = Front Components & Rear Coaxials
Page 4 = Wiring
Page 6 = Audi TT Details