Being disappointed with the stock 6.5" Harman Kardon sub-woofer, I searched for straightforward replacement options, but found none for the ML350. I came across esby's posting on his project and it inspired me to try my hand at fiber-glassing. Below is a pictoral summary of the project.
esby went with a 12" JL Audio low profile sub. I wanted to be able to remove the sub enclosure through the panel hatch, so I went smaller with a 10" sub and the same Alpine amp.
Audio Components
10TW3-D4 - Car Audio - Subwoofer Drivers - TW3 - JL Audio
Alpine Electronics of America, Inc.
List of Materials (mostly) from US Composites
List of Accessories
Project Pics
Cardboard mockup to get an idea of space needed. JL Audio recommends .5 cu. ft. for it's 10" sub. I filled a trash bag with .5 cu. ft. of styrofoam peanuts and worked it into the space.
Had to Dremmel off a few unused screw heads that were in the way.
Framed-up the area to be taped with cardboard and a plumbers strap.
Tedious tape job. Double-taped and cascaded like shingles to prevent resin leaks.
Applied Pam spray for mold release which worked ok, but not great. Should have used car wax.
Single layer of a mix of biaxial mat for large areas and chopped mat for tight corners.
Let cure overnight, remove tape, and carefully wiggle shell out of space.
Fabricated a terminal cup ring from 1/2" MDF. Fiberglassed it into place on the bottom front of the enclosure. You can see the dark ring through the fiberglass.
Backside of enclosure with contours matching install space.
6 layers of fiberglass for a 1/4" to 3/8" thickness. Shell weighs nearly 10lbs and feels sturdy.
Shell fit test in the space and created an MDF template out of foamcore board.
Checked volume using .5 cu. ft. of styrofoam peanuts. Knowing the MDF and sub will occupy the enclosure, it looks close enough.
Fabricated MDF facade and recessed ring. Drilled mounting holes and installed t-nuts. Installed 3 metal tabs to aid in securing the MDF to the shell. The top tab (left in pic) will remain for mounting in the space, the other 2 removed later.
This pic is from inside the enclosure looking up at the seam between the shell wall and the MDF. Before fiberglassing the facade, I wanted to fill the crevice for added strength. I used large rubberbands across the back of the enclose and hooked over the tabs to keep the MDF in place. I taped over the gap all around the front of the facade. Then I mixed a slurry of resin and Duraglas, added hardner, and poured it around the inner shell wall into the gap.
Front fiberglassed with 2 layers of chopped mat and sanded. I tinted the resin with black dye so I could see where the shell and front met during sanding. Terminal cup hole cut out with Dremmel.
Enclosure carpeted. Terminal cup and sub wired and mounted. Briefly, the amp is 4Ω and the dual voice coil sub must be wire in serial (8Ω) or parallel (2Ω), so the only choice is parallel illustrated here.
Disconnected the stock sub amp (just to the right of the old stock HK sub) and identified the line-level inputs and remote power-on wires.
Found space for the amp under the rear seat in the center. Used a small piece of wood and velcro to secure the amp. The crossover is set at 120Hz, gain at a notch less than center "Nom", and equalizer set to +1db.
Now weighing in at 25lbs, the sub & enclosure seated well, but still felt like it could possible move during aggressive driving :grin and certainly during an accident. So the tab screwed to the MDF and fiberglassed over, proved useful. I fabricated a bracket with wing-nuts for easy removal and used an existing but unused frame bolt. This holds the box in place and, hopefully, will never be tested by an accident.
In it's hole, connected and secured.
Conclusion
Overall, I'm pleased with the results. Being a fiberglass n00b, I probably spent over 50 hours spanning 2 months on this project. Cost of materials was over $100. Electronic accessories were $50. The amp was $160 and the sub was $270.
Based on research and input from other forum members, the crossover is already set at the head unit or the amp under the driver's seat and is tuned for the 6.5" HK sub. So, I'm probably not getting the full range potential from the JL Audio sub, but it still sounds great. I'm not a thumper, but a good sub really makes a system.
Hope this post helps with anyone deciding on this kind of project.
John
esby went with a 12" JL Audio low profile sub. I wanted to be able to remove the sub enclosure through the panel hatch, so I went smaller with a 10" sub and the same Alpine amp.
Audio Components
10TW3-D4 - Car Audio - Subwoofer Drivers - TW3 - JL Audio
Alpine Electronics of America, Inc.
List of Materials (mostly) from US Composites
- A good respirator for resin/hardner fumes!!!
- Multiple N95 grade respirator masks for fiberglass dust during grinding/cutting/sanding
- 2 rolls of blue painters tape (fine)
- 1 can of Pam for mold release
- 2 yards of biaxial 45° (1708 & 1208) fiberglass
- 2 yards of 3/4oz chopped strand mat fiberglass
- 1-1/4 gallons of 404 polyester resin w/hardner
- 1 quart of Duraglas
- 6 cheap 2" brushes, 6 cheap 1.5" brushes
- 6 popsicle sticks or other stirrers
- 6 16oz graduated measuring/mixing tubs
- MDF 3/4" - 4'x4' for recessed sub ring and facade
- MDF 1/2" - 1'x1' for terminal cup ring
- 8 black hex screws #8-32 1-1/2" with matching t-nuts for sub mount
- 4 black pan-head wood screws 3/4" for terminal cup
- Scissors and razor blades
- 12"x12"x6" box to measure out .5 cu.ft. of styrofoam peanuts
- .5 cu. ft. of styrofoam peanuts
- 1 sheet of foamcore board for MDF template
- Router, jigsaw, Dremmel, and drill to make sub ring and terminal cup ring
- Handheld grinder to cutaway excess fiberglass...use Dremmel if you don't have one
- 6 Sheets of 60grit sandpaper
- Can of 3M 77 Spray Adhesive
- Speaker enclosure carpet
List of Accessories
- Terminal cup with terminals
- Amp install kit (4 AWG power & ground leads & remote turn-on wire)
- 6' phono cable
- 12' 12AWG speaker wire
Project Pics
Cardboard mockup to get an idea of space needed. JL Audio recommends .5 cu. ft. for it's 10" sub. I filled a trash bag with .5 cu. ft. of styrofoam peanuts and worked it into the space.
Had to Dremmel off a few unused screw heads that were in the way.
Framed-up the area to be taped with cardboard and a plumbers strap.
Tedious tape job. Double-taped and cascaded like shingles to prevent resin leaks.
Applied Pam spray for mold release which worked ok, but not great. Should have used car wax.
Single layer of a mix of biaxial mat for large areas and chopped mat for tight corners.
Let cure overnight, remove tape, and carefully wiggle shell out of space.
Fabricated a terminal cup ring from 1/2" MDF. Fiberglassed it into place on the bottom front of the enclosure. You can see the dark ring through the fiberglass.
Backside of enclosure with contours matching install space.
6 layers of fiberglass for a 1/4" to 3/8" thickness. Shell weighs nearly 10lbs and feels sturdy.
Shell fit test in the space and created an MDF template out of foamcore board.
Checked volume using .5 cu. ft. of styrofoam peanuts. Knowing the MDF and sub will occupy the enclosure, it looks close enough.
Fabricated MDF facade and recessed ring. Drilled mounting holes and installed t-nuts. Installed 3 metal tabs to aid in securing the MDF to the shell. The top tab (left in pic) will remain for mounting in the space, the other 2 removed later.
This pic is from inside the enclosure looking up at the seam between the shell wall and the MDF. Before fiberglassing the facade, I wanted to fill the crevice for added strength. I used large rubberbands across the back of the enclose and hooked over the tabs to keep the MDF in place. I taped over the gap all around the front of the facade. Then I mixed a slurry of resin and Duraglas, added hardner, and poured it around the inner shell wall into the gap.
Front fiberglassed with 2 layers of chopped mat and sanded. I tinted the resin with black dye so I could see where the shell and front met during sanding. Terminal cup hole cut out with Dremmel.
Enclosure carpeted. Terminal cup and sub wired and mounted. Briefly, the amp is 4Ω and the dual voice coil sub must be wire in serial (8Ω) or parallel (2Ω), so the only choice is parallel illustrated here.
Disconnected the stock sub amp (just to the right of the old stock HK sub) and identified the line-level inputs and remote power-on wires.
Found space for the amp under the rear seat in the center. Used a small piece of wood and velcro to secure the amp. The crossover is set at 120Hz, gain at a notch less than center "Nom", and equalizer set to +1db.
Now weighing in at 25lbs, the sub & enclosure seated well, but still felt like it could possible move during aggressive driving :grin and certainly during an accident. So the tab screwed to the MDF and fiberglassed over, proved useful. I fabricated a bracket with wing-nuts for easy removal and used an existing but unused frame bolt. This holds the box in place and, hopefully, will never be tested by an accident.
In it's hole, connected and secured.
Conclusion
Overall, I'm pleased with the results. Being a fiberglass n00b, I probably spent over 50 hours spanning 2 months on this project. Cost of materials was over $100. Electronic accessories were $50. The amp was $160 and the sub was $270.
Based on research and input from other forum members, the crossover is already set at the head unit or the amp under the driver's seat and is tuned for the 6.5" HK sub. So, I'm probably not getting the full range potential from the JL Audio sub, but it still sounds great. I'm not a thumper, but a good sub really makes a system.
Hope this post helps with anyone deciding on this kind of project.
John
