>Mike,
>you could always try boarding-in the recess behind the A-post and fixing in
>a speaker to that...
>It should make a good infinate baffle bass box...
>Infact if you wanted to go mad you could put a hole in the top of the sill
>behind the A-post and then the Whole sill box would be part of the baffle!
>Theres nothing like making the car into a speaker!
>Cheers
A bit long this, but it should be everything you need to know to build some
excellent speakers.
First think I would say, dont what ever you do cut or do anything to the
original panels. Remove them and make copies, I have even made copies of
the wheel arch panels, which are probably the hardest to copy.
>From experiments I have performed, metal makes a rubbish speaker cabinet.
Up front I have two speaker mounted on a some thick board. These are then
wedged out the way. These are fed from my crap 4W RMS radio. So I got a
20W RMS Alpine and put in the back, and another pair of speakers.
First attempt was in the panels above the wheel arches, abit of fibre board,
and some water and I had perfect copies, to experiment with. The long
chamber should produce good base. I didn't, the base was rubbish, not
enough back pressure.
The DPO had made a bodged attempt to put speakers into the rear trim panel
covering the fuel tank. Both speakers together in the centre, too high so
the magnets catch on the fuel tank. I removed the tatty cloth covering the
holes, and tidied up the area, reinforcing it. I then mounted the speakers
top and bottom (not sides). And replaced the panel, the speakers caught on
the fuel tank, and the panel then bent out in the middle, hence not mounting
them at the side. I then got some CLEAR silicone rubber bathroom sealant,
and filled the gaps. The result is a lot neater than the ugly holes left by
the DPO, and I can here the music a 70MPH with the top down and a blowing
exhaust.
The front compartment, compartment between the fire wall and 'A' post like
Tim says is Ideal. You should have about 10L to play with, if I remember
correctly. Your best choose would be to make a copies of the panels out of
MDF. Then measure out the internal space behind the panel, and make a box
to fit behind there giving the biggest internal volume. For the speakers I
would not use car speakers (they will not work with the amount of back
pressure you'll get).
The driver you want has to work with very little space, either go into the
shop and tell them what you are after, or look for a second hand speaker
where the box is the same size. I favour second hand. In cars its normal to
have 4ohm speakers, look for 3 to 6ohm on the cabinet or check the stereo in
your car can deal with what ever the speaker is. If you have a chose, look
for for a sensitivity rating, 87db is ok (assume this or lower if they are
not marked) 90db is good, 92 is excellent. It works like this, 10W RMS
driving a 92 dB speaker is as loud as 20W driving a 90dB speaker which is as
loud as 40W driving a 87dB speaker. Anything quoting power in units other
than RMS is crap, and you ideally want a power rating of 20-30W RMS. If the
speaker is ported, you need to mount the port so its the same length some
where in the box. Mount the speaker in the box, I then suggest if its paper
spraying it lightly with some clear lacquer both sides to stop the damp.
The tweeter should be chucked away unless its really clear and not made of
paper. Next mound the new tweeters with kevlar cones in clear view of the
driver and passenger, they should be able to see both. The impedance of the
tweeter doesn't matter, so you can have a 4 ohm driver with a 8 ohm tweeter.
You should get a cross-over in the speaker, this needs to be wired in. I
suggest putting it behind the panel, having a audio in and tweeter out on
it. Little stands under the dash could hold the tweeters to the left and
right sides.
This system should be quite loud, although you cant really expect sub 150Hz
sound from it. But the quality will be far better than another car you have
driven. You will however need to get some sound proofing for the car,
especially if you have a fibre glass gearbox tunnel which lets all the sound
through. The fire walls, and the bonnet make ideal candidates for sound
proofing, same as rear and front wheel arches, the cross supports in the
floor pans and where the trailing arms bolt on to the body.
Note 4W RMS can be very loud, my SB 16 connected to my home speakers is very
loud. I am a big fan of oval speakers, these are so much better than more
expensive round ones. My home speakers are home made slim-line
transmission line speakers 8' internal pipe. The are driven with 2.5" x 5"
car speakers costing £20 the pair. One cone and coil covers 50Hz to 14kHz,
and driven with my 30 year old valve amp they beat 300 quid systems for
clarity and impact. For example you can here the extra noise, even locate
it in the stereo field when they open a microphone channel in the recording.
Not bad for an outlay of £50.
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