rotarywanker

All,

Made this and thought I would post some pictures. Also posted it over in the audio section.

I used the traditional fiberglass method that you can read about anywhere online:

1. Cover area in trunk to be fiberglassed with blue painter's tape (I also smeared with vaseline, which worked very well as a mold release agent after everything dried)
2. Start with a layer of carefully pre-cut fiberglass CLOTH. Use only enough resin to soak through the cloth - nothing more. A lot of people online seem to think adding resin adds strength, while the opposite is true.
3. Then add a layer of fiberglass MAT. Continue alternating between CLOTH and MAT, using just a little bit of resin each layer. I used a total of about 10 layers by the time I was done. You do not wan't to be able to flex the enclosure at all for optimal sound reproduction - sitting on it is a good test here.
4. Cut a recessed ring out of 3/4" MDF using a router or a dremel with a circle cutting attachment (this is two rings for those who don't know, one to recess the woofer surround).
5. Prop up the ring in position using wooden dowels or blocks (these are temporary, use hot glue)
6. Stretch a piece of fleece (blankets work well) over the ring and secure it to the fiberglass shell using hot glue (just a little bit). The fleece should be very tight as it will sag under the weight of the resin.
7. Cover the fleece in resin. Use enough to completely saturate the fleece, but no more.
8. Apply several layers of fiberglass MAT to the inside of the fleece. This part is a pain - take your time to get it right. I ended up adding about 4 good layers here before all of the flex was eliminated.
9. NOW - and this is important, measure the volume of the enclosure using packing peanuts (can be compared to a cube of a known volume). If the enclosure is too large for your speaker, add some low-expansion foam (like Great Stuff) to the corners of the box. Repeat until your volume is perfect. This will really help your speaker sound its best.
10. Cover the enclosure using carpet. I was lazy and went with carpet I found at wal-mart which is not a great match for the RX-8's factory carpet. This step really sucks depending on how many contours your box has. I recommend covering in 2-3 separate pieces - just take care to place the seams in an inconspicuous area.

I should also note - I have a factory BOSE system. I tapped into the pre-amp signals for the rear speakers. If your amp can handle balanced pre-amp inputs, I HIGHLY recommend going this route. This will give you a cleaner signal. I've experimented using both pre-amp and speaker-level, and the pre-amp allows the sub to 'blend in' much better across all genres of music. Also allows you to keep using AudioPilot if you like it. All of the current Alpine sub amps accomodate this.



I am using the Alpine MRV-M500 amp and a 12" 4 OHM Alpine Bass Line sub. This sub is a great value. I've had Kicker Comp R's and JL W3's in the past and this sounds just as good if not better (at least than the Kicker subs). Gets plenty lound and goes down to almost 20 hz cleanly.


I also recommend going the 12" route. More area really does help a sub produce volume at low frequencies without struggling as much.


Hope this is helpful.