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| the culprit(s) this time: a pair of 15W0v3-4 from JL Audio |
I have touched lightly on the topic of Box Builds before. Being a lifelong musician/audiophile has its advantages and disadvantages. In my case it has been an ongoing and seemingly insatiable addiction to upgrading my sound systems in order to 'get more' out of my music. At times the boxes have been ridiculous, at times they were cut and assembled by TJ down by the trailer park, but at the end they have all been a learning experience in sound dynamics.
Here I bring you my latest creation, starting with a simple CAD file which incorporates a few geometry constraints all the way to a finished product, with all parameters met, and installed in the intended vehicle.
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| Basic specs of the woofer. |
It is hard to describe the feeling of owning a car with bass that can rattle the windows of houses which are blocks away. I am fascinated by the whole concept of the system and how tweaking certain components yields different results, thus giving your system a personality of sorts which can be tweaked according to your musical tastes and preferences.
Ultimately the subwoofer is only 1 component of a much larger array of components which ranges wildly in shape and application such as ground wires, amplifiers for mids/highs and lows, a properly selected power wire, proper routing of your sound wires, soundproofing, proper sealing of cabin, etc, etc.
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| Trunk area of the 2009 Matrix S. |
The main design constraints are as follows:
1. Overall Height 16" Max (oem snap-on vynil tonneau height)
2. Overall Width less than 41.5" (overall width of trunk)
3. Individual Chambers with 1.875 cu. ft. of internal volume (per subwoofer manufacturer's specs)
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| The ideal box for this woofer has a net internal volume of 1.875 cu. ft. |
Other constraints will be covered later under the Notes subsection of our fabrication drawings, however; the size was the most important issue and the sides were chosen to remain around the 36" to 38" mark. The external height of 15.75 was fixed at 16.0". The depth however was allowed to grow much further in order to allow for proper volume.
The volume was 1.875" per the manufacturer's specification. We will test this box and see how it performs.
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| Close enough at 1.874548 |
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| Page 1/4 - Views showing location of box in relation to vehicle fixtures. |
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| View showing metallic tie-down attached on the woofer box, and floating tie-down on vehicle location. |
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| Page 2/4 - Note chamber separator, and dual terminal cups. |
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| View showing all exploded components |
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| Page 3/4 - Fabrication Schematic and Notes. |
NOTES:
1. MATERIAL: 3/4" MDF. The material of choice is 3/4" MDF medium density fiberboard which essentially comes in at 0.71" so this is taken into consideration when designing the box in SolidWorks.
2. FASTENING: WOOD STAPLES OR WOOD SCREWS. The Option is given to the fabricator to select between staples or wood screws. Due to weight issues we recommend using staples.
3. TERMINAL CUP: JL AUDIO 5 WAY TERMINAL CUP. The JL Audio Terminal Cup is a multi-use connection system which is only sold through authorized JL Audio dealers. It allows for connection to a wide array of wire sizes.
4. TIE-DOWN FIXTURE PROVIDED BY CUSTOMER. The Tie-Down is a simple ring style tie-down which is made out of chrome-plated stainless steel. Proper securing of the box is a vital yet very commonly overlooked item of the checklist of good practices. A box which is not tied down will be the subject of a plethora of problems.
5. CARPET COLOR: DARK GRAY/BLACK. The Carpet color will most likely be decided on site depending on which color carpet they have available. I specify two colors which I think would be acceptable on the target vehicle.
6. FILLET SEAL ALL INTERIOR JOINTS. It is good practice to install all parts wet and fillet seal them on the inside with proper sealing compounds.
7. FILL WITH POLY-FILL TO MANUFACTURER'S SPEC. Usually the Poly-Fill amount should equal the amount of the internal volume of the enclosure. Less or more poly-fill can later be added or subtracted in order to change the sound of the speaker.
8. TO BE DELIVERED CLEAN, FREE OF DEFECTS. You can specifically ask the builder to vacuum it and shrink wrap it after fabrication. You will probably spend a pretty good amount of money for a box this size, ask for them to give you a clean new product.
9. IF IN DOUBT, ASK. Provide your information and tell them you'll be available any time of the day to answer any questions they may have. Even if the assembly is an easy build, it is good practice to leave this note on all your drawings.
Side Note: These notes should be reviewed one by one with the builder, to ensure they understand all of them and are able to execute all of them. You must select the proper method (staples/screws) and the carpet color (dark gray/black) also the other items (subwoofers, terminal cups, grilles, etc) must be purchased.
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| Page 4/4 - Fabrication Drawing |
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| Positioned within the trunk area with the vynil tonneau set in place |
The box fabrication is completed within 5 working days and I get a call on a Friday telling me to come pick up my box, that it is ready.
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| Soon... |
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| Exactly what the Doctor ordered. |
The shop had pre-assembled the Terminal Cups as well as soldered the wires to the terminals on the inside. They actively double-checked the color coded wire for correct connection orientation and proceeded to mount the subwoofers using #8 wood screws. Then they attached the grille into place using nothing but the pressure between the two parts (per the manufacturer's installation procedure). Lastly the metallic tie-downs were installed per the instructions.
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| The dual 15's box inside the trunk area. All 5000 pounds of it. |
Once the box was transferred into the car the tie-downs were deployed as planned and the proper connections were made with the wiring which had been laid in place.
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| Individual Inputs from the amplifier to each driver ensure balanced delivery of power |
The finishing touch is the OEM vinyl tonneau cover which conceals the subwoofer from prying eyes and opportunists.
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| Expect vibes from this little wagon. |
This massive super contender is able to extract bass from the dullest song you can find on AM radio. It will make the morning news sound like horses are galloping with you. It can turn any country ballad into a beastly intersection destroyer. Anything with decent bass will have people advancing at the traffic light in order to get themselves and their poor child's ears away your satanic concoction of electronic components.
Final Verdict: The dB's are High, the MPG's is Low.
Unfortunately this box features a high amount of MDF board which is very heavy. An alternative method would feature a box solution that utilizes the lower compartment of the trunk for the needed volume, perhaps even a ported box solution. More on this in a later post...
The Assembly for this Installation can be downloaded over at GrabCAD and it includes the mockup of the 15W0v3-4 subwoofer. Also included is the drawing file for the assembly and fabrication. There are several configurations that include exploded views, as well as named views for rendering certain angles of parts. Materials are asigned to all parts.
Until next time,
Antonio Suarez
Industrial Designer
