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Old 29th December 2004, 04:59 PM   #1
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Angry need a sub for ~22.5 cu ft trunk

I need some ideas for a subwoofer for my car. I have ~22.5 cu ft trunk, but I don't want a box in there. I was thinking about putting a baffle behind the rear seats, and mounting the sub(s) to it. Would that work as an IB or as a box? What drivers would be good for this application? I'm looking for a fairly high sensitivity, lots of xmax, and good power handling (not too expensive).

Any other ideas are welcome.
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Old 30th December 2004, 06:26 AM   #2
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As I see it, there are a couple of problems with the idea.

If the trunk is open, or there is an issue with the weatherstripping, the trunk will be an infinite baffle -- we hope!

Assuming that you can seal the trunk, anything in it will alter the effective chamber volume, which will in turn alter the sonic performance of your sub.

Sealing the trunk is often more difficult than you might think. Typical trunks are designed not to be completely sealed from the passenger cabin, this is to prevent anything from getting really ... ripe in the trunk. Similarly, the car is not designed to be sealed from the outside world. If it were, you might have a bit of trouble breathing on a surprisingly short trip with the ventilation set on "recirc!" Actually, the trunk is generally the exit point for the cabin air, so it's also not sealed from the outside, however, the opening isn't likely to be free enough to be considered infinite baffle. It's possible (likely?) that the exit will prove to be like some sort of port. It may end up that what you end up making is in essence a dual reflex bandpass enclosure, with the trunk and cabin of the car as the chambers. Could be great for setting off car alarms, but not likely tobe so good for sound inside the car.

For drivers, choose somethign that will work for infinite baffle, and hope for the best, because it will be practically impossible to tune such an enclosure, save by adding things to the trunk until it sounds right...

As per your other thread, I certainly hope you're not planning on putting in 4kW into this system!

It could be done, but as I said, there's no way to know for sure what you're going to get until you do it.
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Old 2nd January 2005, 05:08 AM   #3
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Quote:
It's possible (likely?) that the exit will prove to be like some sort of port. It may end up that what you end up making is in essence a dual reflex bandpass enclosure, with the trunk and cabin of the car as the chambers. Could be great for setting off car alarms
I really like that idea
Quote:
For drivers, choose somethign that will work for infinite baffle, and hope for the best
I would rather come up with something that will sound good , than waste money and time creating something that will probably sound like sht.

I did some thinking. I can fit a 2-2.5 cu ft box in my trunk and still have some (a lot of) space left (I don't want to take up the whole (or most of the) trunk with a box). Which driver(s) and in what kind of box (sealed/ported) would be good? I'm mostly going for sound quality, but hitting 120+ dB would be nice too.
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Old 2nd January 2005, 07:34 AM   #4
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120+ dB isn't hard to do. I've got a pair of 0.65 ft^3 boxes with 10" subs in 'em and 60W/sub, and it hits 130 dB SPL. I have some tweaking to do for SQ, after which I might be reduced to a "mere" 124dB SPL or so, worst case, as I've been measuring it.

It's my opinion that there's no need for anything larger than a 10" sub for car audio. With the cabin gains typically experienced, these are plenty large enough. Keep in mind that I'm not an SPL guy.

A nice set of woofers and a reasonable amp should be able to get you to those goals.
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Old 3rd January 2005, 03:27 AM   #5
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Quote:
Originally posted by SupraGuy
A nice set of woofers and a reasonable amp should be able to get you to those goals.
I was looking for suggestions on which sub(s) to get that would work good in a 2-2.5 cu ft box.
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Old 30th January 2005, 12:20 AM   #6
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Quote:
Originally posted by xplod1236

I was looking for suggestions on which sub(s) to get that would work good in a 2-2.5 cu ft box.
Have a look at the Rage 12" here:

http://www.subwoofers.cc/remain.asp

I have two in 2 cu. ft. sealed boxes, loosely stuffed with polyester fiber matting. They are dual voice coil drivers, each coil rated 4 ohms, 100 watts. One box does subwoofer duty in my HT system, with 120 American watts (old QSC 5.1 stereo power amp) available to each voice coil, with a 90 Hz crosspoint. The second box will soon find a home in the trunk of my newly acquired Civic sedan, which brings me to my question.

Can someone direct me to some good info on running an adequate gauge wire from the battery or fuse panel to the trunk? I think I can do a clean job of installing an amp with integrated crossover in the trunk, and the input and output connections to the amp should be no problem. How do I get a fused 12 volt line to the trunk?

Thanks,

dooper
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Old 31st January 2005, 01:19 PM   #7
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Depending on the power your amplifier can deliver,you'll need to figure out the gauge of wire you will need. 8 gauge wire is a start for a smaller amp,up to say,100W(?) Any more power than that and you're gonna need larger wire.
Tap from the battery (+) terminal(not the fuse box),and put a fuse inline within about a foot of the battery (keep it close to the battery,if something shorts,you don't want to start a fire!)
Run it through the firewall,either find/use an existing grommet,or drill a hole,and fit a rubber grommet in it. (prevents the wire from chaffing,and shorting-> back to the fuse/fire scenario.)
Then run it under the carpet,or door-sill to the trunk.
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