My Subwoofer Speaker

For the subwoofer enclosure, I used 3/4" thick MDF. The driver is the Adire Audio Shiva. This is an impressive dual voice coil driver specifically designed for subwoofer applications. The enclosure plans are from an application note provided by Adire Audio. The outside dimensions are 18" wide, 18" deep, and 22" high. It is internally braced side to side, rear to midbrace, and front to midbrace. The side to side and rear braces extend from top to bottom. The front to midbrace brace extends 5.75" down from the top. The driver is front mounted near the bottom of the front panel. The enclosure has an internal volume of 88.5 liters and has a Q of 0.6.

A single 4' by 8' sheet of 3/4" MDF provides more than enough material for the enclosure and braces. I bought a sheet at a local Home Depot for less than $20. I had the store do a couple of rough cuts to allow easier handling of the material. MDF is a great material for speaker enclosures. It is extremely flat and does not warp. It is also very dense and stiff, which are ideal qualities for speaker enclosures. It drills, cuts, routes, and machines very well with no chipping and smooth edges. Carbide tipped tools are recomended as steel will wear very quickly. It also sands very nicely and leaves a very smooth surface.

MDF also tends to absorb a lot of paint. Two coats of paint are generally needed.

The Enclosure

	This shows the 11" diameter hole for mounting the Shiva driver. The side to side internal brace is visible. The edges of the enclosure were rounded using a router rounding bit. All of the holes were cut with a router and a circle cutting attachment.
	This is showing the rear. The cutout is for the terminal block cup. The cabinet is glued and screwed together. Carpenters wood filler was used to cover the exterior screws.
	This view shows some of the internal bracing. Several 4" diameter vents were cut in the braces. The screws are driven into the rear to midbrace brace. All of the brace edges were glued before screwing.
	This is the completed subwoofer in the corner of our Living Room. It was painted with two coats of flat black paint. The metal grill was part of the Avatar Audio installation kit for the Shiva. The kit also includes mounting hardware, gold plated binding post terminals, wire, and terminals to connect the driver to the terminals. The terminals need to be crimped onto the wire. The terminal cup has two pairs of binding posts, one pair for each voice coil. Each voice coil has a nominal 8 ohm impedance. Shorting straps are provided to parallel the coils for 4 ohm applications.