can anyone point me in the right direction for info on "free-air" designs?

[Joe X]

What amp are you using (it helps a lot if it supports subsonic filtering), most of the times your subs will handle less power on IB, also if you fail to seal off effectively you get cancellation.

[imfrom210texas]

its a boo-boo Boss amp, no sub-sonic filter.. i wonder though, how much trunk is too much or not enough?

[8ight]

its a boo-boo Boss amp, no sub-sonic filter.. i wonder though, how much trunk is too much or not enough?

As far as trunk space, that's indifferent. The Boss amp likely has a pre-set subsonic, you can't really run without it, but you will need an amp with an adjustable SS filter for the best results. IB setups get EXTREMELY low and have great SQ when done right.

[tjamz]

Tips for an IB setup:

Seal the trunk from the cabin, this sounds like a no-brainer but can be difficult to do properly. This means you need to seal the rear parcel shelf, the back seat, the pockets that go over the rear wheels, etc... If it can leak into the cabin, seal it.

Also with an IB setup the trunk acts as your enclosure. So a smaller trunk is kind of like having a smaller sub box, but usually the differences will be minimal since the trunk is still likely to be quite a bit larger than the "optimal" sub box.

If you are looking for an added element of control, you could always try and fashion your own Aperiodic Membrane in front of or behind the woofer. Basically this becomes a resistively leaky box that in theory will produce the snappy bass on higher sub frequencies yet still go deep on lower frequencies. In the early/mid 90's these were almost a must have for SQ competitors.

A good subsonic is good to have, but again, subsonic filters have become a "standard" on amps only in the last decade or so (maybe late 90's) and cars still sounded great in IB setups before then as well. It's not like a vented enclosure where the sub loses all linearity below it's F3 point, in this case it is still a linear roll off of about 6 dB/octave since it is just a large sealed box.

[imfrom210texas]

now that $hit right there... that $hit right there.. thats an answer for that a$$ lol. honestly, it just seems like to much trouble to make it airtight, and i dont see it being worth it after all. i can just use Torres Calc to make a proper vented box. Thanks to all for any and all help that was given

[STEvil]

For the record you can also run without the trunk sealed, you just need to provide a path for the wave that is long enough to not allow the sub to act in a free-air manner.