Matt's center channel page


under construction This is from my archived web pages. The Sound Clearing house is no longer in business. Too bad... nice friendly folks.

The box
I can solder up a storm but I am a crappy wood worker so I tried to make the cabinet simple. The local Home Depot has medium density fiberboard (MDF) already coated with white primer and cut into convenient widths. The Home Depot will cut the wood for you using their large industrial saws which give wonderfully flat cuts. I made the dimensions of the box so I could get the volume I wanted by only cutting the wood in one direction leaving two perfect sides on each piece. You will notice every piece of wood has a dimension of 5.5 inches. The top, bottom, front, and back are 5.5" by 17+3/8". The sides are 5.5" by 4+1/8". See the drawing at the bottom of the page. My dimensions give an optimum volume for a sealed enclosure. Three box volumes are given on the Sound Clearing House web page for the 4" woofers (model SO4162). Two for ported and one for sealed. A diagram for one of the ported designs came with the kit and is on their web page under "kits". The volume of my sealed box is about .21 cubic feet.
I used 1" long dry wall screws to hold the box together. I counter sunk the screws using a drill bit slightly larger than the screw head. This made sure that plenty of screw went through to the next board. You can then fill in the holes with wood putty for a flat surface. I used silicone to make the butt joints air proof. I stuffed the box at least half full with acoustic insulation. That is the last time I buy that nasty fiberglass stuff from Radio Shack. I should have waited and ordered the cotton looking stuff.

The speakers
The shielded 4" mid/woofers don't have a lot of overhang on the mounting lip so if you mount them from outside make sure your holes are just barely big enough to accept the speakers. If you mount them from the inside then the gasket surrounding the speaker would probably seal it nicely. I mounted my woofers from the outside and used a small bead of silicone to seal the speaker to the box. I tried them without silicone and I could feel the air leaking during large cone movements. The tweeter should be mounted from the outside. I did not flush mount the speaker as The Sound Clearing House says that very little improvement is gained by doing so. I don't have a router so that pretty much clenched it. The tweeter is not shielded and I could tell before I made the box it was going to cause problems. The Sound Clearing House sent me a magnet to glue on to the back of the tweeter. That canceled out virtually all offensive magnetic fields. I can lay the tweeter right on top of the T.V. and there is no distortion. The gold five way binding post (on a plastic insert) come with the kit and look very nice. It was mounted from the outside and sealed with silicone.

The crossover
The crossover comes with the kit and consists of a 12db/octave capacitor/coil combination for the woofer and a 6db/octave setup for the tweeter. The coil on the woofer is a iron core variety. A very small coil is included to be put in series with the tweeter. This coil rolls off the highs a bit as the tweeter is a little bright. I tried the center channel with and with out the coil and I definitely like the sound better with it included. A schematic of the crossover is included with the kit.
box dimensions

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