I am looking into building a sub box and wanted to know what the best position for aiming the sub would be. I was going over the ideal of having the box against the back seat with the sub pointed upwards at the rear deck. My intention would be to remove the factory sub and put the new one directly under the opening. A facade would be in place to separate that area from the rest of the trunk.

I have been told by a couple of local shops that if I place a sub box in my trunk against the back seat with the sub facing up, a 3+ db gain would occur.

What do you guys think? Would it be better to just point the sub towards the rear of the trunk or maybe towards the back seat?

So do whatever you like. I fire mine towards the back of the trunk, into open air. This, in general, should produce higher SPL.

+ or - 3dB isn't going to be audible if you're already pushing > 120 dB from your subs.

I remember reading that a while ago - I think Dynamat used to market their product with that concept (they helped you gain 3 db, which in turn made it sound like you doubled your output).

It takes 2x the power to produce +3db. So if you're running your current sub with 100w you can get another 3db by going with 200w and another 3db if you go to 400w and so on. Typically, aiming the sub at the back of the trunk gives the best results. I can't say I've ever heard that aiming it up would have specific benefits. It's not necessary to vent the sub into the cabin since the wavelength of low frequencies are very long and easily travel through obstructions like the rear deck and seats. My suggestion would be to build a temporary box to experiment with placement. If you make a simple MDF cube it should only take an hour or so and cost less than $10...Home Depot sells 2x4 sheets of MDF for about $5 and they will cut it to your specs on their industrial table saw for $.25 per cut...all you have to do is glue and screw.

200 watts on one 10" sub, versus 100 watts on each of two identical 10" subs.

200w on one 10"...step down to 100w (down 3db) plus another 10 inch with 100w (back up 3db)

"Basics:

When you double the cone area (add a second speaker with equal properties) while keeping the power constant, you gain 3dB of output.

If you reduce the number of speakers by 1/2, you lose 3dB.

If you double the power to a driver, you gain 3dB.

If you cut the power by 1/2 you lose 3dB.

If you double the cone area and the power (by paralleling the second speaker on the amplifier), you gain 6dB."*


This isn't pure physics, but it is well documented.<ul><li><a href="http://www.eatel.net/~amptech/elecdisc/xoorder.htm">*Basic Car Audio Electronics site (aka,</a></li></ul>

Feeding half as much power to twice as many speakers...

between two identical speakers.