Volume of box
 

im building a dual 12" sub enclosure. It is a bass reflex bandpass setup with 4 ports. I need to know what the ideal volume of the box should be behind the speaker. Here is a picture that kind of describes what im talking about. Its not the half with the port, but the bottom half, below the speaker:

http://www.diysubwoofers.org/bnd/4thordbp.gif

Are the two areas supposed to be equal in volume? Please help. Thanks in advance.

- Philip

Obviously the size of the chamber depends entirely on what the sub is optimized for, and what kind of sound you want to get. As far as the relative size of the two chambers, I think it depends on the port length and size, but they should be close if I recall correctly. Might want to consult a book about box-building.

Enclosure construction is not guess work and you need to build your enclosure around the subs you intend on using. You need the full set of T/S parameters (Thiel/Small) to start with.

Your best bet is to have someone design the enclosure using a computer based application. With the application you can get exact front/rear volume sizes (taking into consideration the volume consumed by the sub and the ports) and also get the exact port sizes necessary.

Maybe your local high end audio shop might have an application (LEAP, TermPro etc)

Do also keep in mind that the passband on the type of enclosure you want is limited.

good luck

Gotta agree. You have to have the sub's parameters and then calculated all box dimensions, including port length and diameter, from them. If you don't you will have a crappy sounding sub setup or worse, blow your subs by exceeding their excursion limits.

thanks for the info. I checked up on everything and layed it out. Turned out it would be too big to fit in my trunk so im sticking with a ported box. its all tuned and matches what the speakers call for. thanks for the help everyone.

///Philip