June 27th, 2003 : Designing & Building Speaker Cabinets
When I got my truck it had an old radio/cassette player in it and four speakers, but I wanted to upgrade everything, so I purchased a 1955 AM/FM Cassette Chevy stereo. Initially, I tried putting the speakers behind me, overhead, but that sucked ... then I tried putting speakers under the seat, facing forward, and that sucked even more ... it appears a truck cab is just too small a space for four speakers -- sound bounces around too much and you lose separation and clarity. The only place that projected decent sound was on the floor, facing me ... so I decided two speakers (one in each kick panel) would do the trick. I don't like putting speakers in the door panels for three reasons ... first, running wires can be troublesome during as well as after install ... second, the speakers tend to get kicked a lot in that location ... and third, the sound tends to get blocked by legs and feet.
The next thing was to buy new speakers, but I had no idea how to go about matching them to my system ... so I asked around and got the answers.The basic deal is this : If your stereo puts out 20 watts per channel, you want 40 watt rms (or more) speakers ... notice that's rms, not what's advertised on the box! I wound up buying Sony Xplod Speakers Model xs-W1620 -- on the box, it says 160 watts, but the true rms rating (found in the brochure specs) is 50 watts -- see what I mean?My idea was to get the speaker on the driver side to point at the passenger's head, and to get the speaker on the passenger side to point at the driver's head ... so I took a piece of plywood that I had cut to mount the speaker on, placed it in postion, and did some measuring from the kick-panel, out, to each corner of the front-panel. This called for some serious compound angles! The top-left corner of the speaker box was to be three inches out from the kick panel ... the bottom-left was to be five inches out ... the top-right was to be one inch out ... and the bottom-right was to be two inches out. Crazy cuts ... but I started marking and cutting up some 3/8-inch plywood :
First, I cut out the front and back panels for each speaker box at 8.5 inches square ... the back panels weren't exactly square though, due to the compound angels that had to be compensated for.
Here's a shot of all the pieces, plus one speaker box assembled, roughly, with some duct tape.
Next, came the assembly. Once I decide on which type and color of carpeting I'm going to install in the truck, these speaker boxes will be covered with the same carpet ... so precise and exact cuts and fits aren't as crucial as they would be if I was covering them with vinyl. I used Elmer's glue and 5/8-inch brads to secure the pieces and braces together, and wrapped them with duct tape "straps" to further secure them while they dried ... then, I filled any gaps with silicone caulking and left them to dry over-night. Once they were dry, I packed the insides with Thermal and Sound Control Fiberglass Insulation (purchased at Home Depot) and drilled two holes through the back panels for mounting.
Finally, I mounted the boxes on eack kick-panel in the truck using 1.5-inch sheet metal screws (to allow for the back panel and later, the carpet, and the jute insulation) ... then put the last piece of fiberglass in the back ... plugged the wires to the speakers (I had drilled a hole in the top of each box to run the speaker wires) and mounted the speakers.
Then I turned the radio on and cranked 'em up! Ooh, yeah!!! Perfecto!
I thought, when I do the carpeting, I might cut into the kick panels and recess the boxes ... but after looking further into the matter, I realized it can't be done -- the fender mounts and bolts are in the way. Also, now that I've had the pleasure of experiencing these located as they are, I've decided to put them behind the seats. Getting in the truck with a closed umbrella on rainy days has enlightened me further -- these are in the perfect place for scewering with the point of a closed umbrella! You know ... when you get in the truck, close and shake an umbrella ... what's the next step? Right hand and umbrella handle back ... point of umbrella over ... and then down to the passenger floor area! LOL! I've nearly taken that speaker out a number of times. And they're taking up too much floor space, too.