Introduction











Step 1: Planning Enclosure Design



Before I could plan or build the box, I needed to have the exact measurements for the speaker and calculate the volume of the box. This is required to ensure the speaker has the optimum environment and will produce the best sound. Damage to the speaker and/or poor sound is possible with incorrect measurements.

There were various sites offering calculating programs and general enclosure designs. It doesn't really matter what shape the box is, as long as it fits the trunk of the car, and has enough room for the speaker and any ports. After some searching and measuring, I decided on the trapezoid shape for the box.

With the decided shape, it was now time to draw up some plans. Any 2D drawing program will do, but TurboCAD for Windows was used in this case.

The plans were to include all the shapes with exact sizes. I knew that my box volume had to be 1.5 cubic feet, so that was factored in. The shots on the right show both the front and side views. Click the images to enlarge. The sub and port was drawn to scale to get an exact position and fit. Dimensions were later added for reference.

These plans would serve as the base for a more realistic rendering of the enclosure. I wanted to get a better idea of the finished product before I started, so I modeled the design in 3D Studio Max.

In the side view, the top and bottom would actually be flat; however, the pieces of MDF are shown as whole entities. Additional cutting and sanding would be done once the pieces are cut.

 

 

Step 2: Modeling the Design

In 3D Studio, I started with all the individual pieces and made them to scale. Holes were cut, and the pieces were then assembled.

I wanted the inside to be insulated so that sound would not leak from the joints, so I added insulation in the box.

The image on the right shows the top and side views (left viewports), and the perspective images. The front slant of the trapezoid design would allow the box to rest up against the back seat of my car. This angle was measured prior to drawing the 2D plans. The back angle is identical, and allows for slightly more room in the trunk.






Step 3: Material Gathering & Measurement Checking


Now that I had both 2D and 3D plans ready, I started to gather my materials. The first thing on the list was the material for the enclosure. I bought a large sheet of 3/4 inch MDF from Revelstoke. Most of the other tools are shown in the picture to the right, with the exception of some of the larger power tools.





The other obvious components are the subwoofer and the amplifier. I got these from Future Shop and was lucky enough to have the same brand for each: Kenwood.




     


Step 4: Building the Enclosure


This next section will take you through the process of building the box. It starts with drawing the plans on the MDF, cutting/sanding the pieces, assembly, insulation, and asthetics. It then finishes with the installation of the enclosure. Wiring is also shown briefly.

The following images detail the process of building a subwoofer enclosure, installing the speaker, and wiring the sub/amp in my car. This project took several weeks, as I had to gather all the materials, calculate the correct volume for the enclosure based on my sub, and build everything. Additional information for my hardware is as follows:

Amplifier

Kenwood KAC-629S

GENERAL FEATURES
- Ground Isolation Circuit
- Power MOSFET Switching Power Supply
- Stereo, Mono, or Tri-Mode Operation
- 2 or 1 Channels of Amplification

POWER RATINGS
- Bridged Power Output at 14.4V (1kHz, 0.8% THD): 150 Watts x 1
- Maximum Output Power: 350 Watts
- Power Output at 2 Ohms, at 14.4V (1kHz, 0.8% THD): 75 Watts x 2
- Power Output at 4 Ohms, at 14.4V (20Hz-20kHz, 0.08% THD):
60 Watts x 2

AUDIO FEATURES
- Quiet Turn-On
- RCA Audio Inputs: Gold-Plated
- Speaker Connectors: Gold-Plated, Screw-Type
- Speaker Level Input Terminals: Screw-Type
- Speaker Relay Protection



Enclosure

- 3/4" MDF medium density fibre board
- Carpet insulation (interior)
- Carpet scraps (exterior)
- 3 inch pipe for port

Subwoofer

Kenwood KFC-W3003

GENERAL FEATURES
- 12 inch diameter
- Power Handling: 600 Watts
- Frequency Response: 25Hz - 800Hz
- Free-Air Resonance: 32Hz
- Sensitivity: 93dB
- Impedance: 4 ohms
- Magnet Weight: 42.3 oz
- Speaker Connectors: Gold-Plated, 2-Way SB-Type
- Speaker Displacement (cu ft): 0.141
- Rec. Ported Box Dims: 1.50 cu.ft.
- Recommended RMS Power: 160W
- Heat-Resistant Polyamide Damper
- Urethane Surround
- Vented Voice Coil: 2-Layer
- Bumped Yoke
- Extended Pole Piece: Vented
- One-Piece Cone Design
- Cone Material: Polypropylene (Injection Molded)