My car's a 1984 so it's definitely been through a lot. The rear speakers had paper cones and 18 years of sun had took their toll.
I replaced the rears with two 6.5" speakers that I bought from my friend Jessie. The two new speakers couldn't handle low
end bass though.. so as Dave got started building his sub, I started checking out partsexpress
for possible drivers. Eventually I settled on a 10" that had a low Vas - a speaker that wouldn't require a large enclosure
so that I would still have a trunk after installing it. I took some rough measurements of my trunk and decided that I'd try
to go for a wedge shaped enclosure so that it'd fit well in the trunk against the rear seats.
I started with some 3/4" MDF and after doing some calculations to get
the correct interior volume, I started drawing lines.. by the way, I used the "ported" spreadsheet available from
diysubwoofers.org to check out the frequency responses for various parameters
and to calculate my desired interior volume.
yeah I made do without a good work table or anything. I used my craftsman
rotary tool (think dremel) with a router attachment to cut the circle.
I did the rest of the cuts with the circular saw including some pretty
questionable angled cuts... I got some tile caulk to seal the cracks.
here's a closeup of caulking.. i was proud of it
I guess at this point, I'd finished cutting the wood and had screwed
and caulked the pieces together. I bought Dave's leftover acoustic stuffing. The stuffing increases the
apparent volume of the enclosure and is useful if you have size limitations.
here's a picture of the driver itself. It's a 10" Pyramid that
is probably still available from Parts Express and other places.
I decided to go all out in making the sub look cool. I bought some vinyl
pleathery fabric (think couches) from JoAnn fabrics that happened to be on sale. I was going to use staples to attach
it but I didn't have a staple gun... so I used spray adhesive.
here's the "finished" enclosure. I built a 2nd order crossover (crossover
frequency of about 160Hz?) and put the capacitors and inductors inside of the box.
this is completely unnecessary but I wanted to appreciate the
difference the sub made in my car more so I decided to try to mount a switch somewhere in my dash. The
cassette player was the easiest component to remove.
I bought a SPST toggle switch from Home Depot, drilled a hole
into the face of my cassette player, and mounted the switch.
here's a picture of the sub sitting in my trunk.
here's a picture of the switch, mounted.
there was a fair amount of cardboard/furry insulation
separating the trunk from the rear seat. I probably messed up any sort of thermal insulation my car's cabin
had from the trunk, but I figured it'd sound better if the speaker was directly in contact with the cabin. Here's a
picture of the speaker and the grille peeking through the armrest hole.
After putting the sub in my car, I still had a pretty major problem - the rear sub was a lot less sensitive than the rest
of the speakers in the car, and the rear speakers were still buzzing. I put a 1st order high pass filter onto the rear
speakers but the problem persisted.. I didn't have enough inductors to make it 2nd order and I didn't feel like ordering
more. Eventually I bought some 10 ohm power resistors from Radio Shack and put them in series with the rear speakers to quiet
them down. It solved the problem but there's probably a much more efficient way of doing it. The sub sounds good in the car -
it can put out a good amount of punchy bass. All together, I probably spent about $85 on this.
-phil
P.S. I know that Pyramid doesn't generally make good speakers. I don't have a separate amp for the sub, though, so it can't get
loud enough to distort.. so it all kind of works out. I'm not going for audiophile quality - just enough so that I can hear the
bass over the horrible road noise and rattling interior.
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