building a sub box

[90Tbird]

ok so i have all my calcluations and my wood, i put most of it together, and now i stopped becuase I just remeberd something, every car sub box that I have seen has isolated the speakers, Im build a box with 2 10 inchers, is it really necessary to split the box in half with a wall and have both isolted or would it be better to leave it an open space?

 

[sploo]

Hi TBird,

If I understand your question correctly, then the answer is a question: what have you done your calculations for?

Different box layouts can have a huge impact on the figures required, especially if you're putting multiple bass drivers in a box (side by side, opposing, isolated etc.).

BassBox Pro may be able to help you:

http://www.ht-audio.com/bassbox.htm

 

[gmichael]

Many people feel that you should separate the speakers so that one does not affect the other's motion. The theory is that not all drivers are the same (even when they are the same model#). If one is driving harder than the other, then it can cause the "weaker" drive to have diminished output.

 

[90Tbird]

Hi TBird,

If I understand your question correctly, then the answer is a question: what have you done your calculations for?

Different box layouts can have a huge impact on the figures required, especially if you're putting multiple bass drivers in a box (side by side, opposing, isolated etc.).

BassBox Pro may be able to help you:

http://www.ht-audio.com/bassbox.htm

well its just a simple square box with 2 10's side by side, but I went ahead and isolated the drivers, its about 1.3 cubic feet per side, minus the insulation and minus the port. Drivers a 300watts a piece. Im just in the process of calculating port hole diameters now.

 

[sploo]

well its just a simple square box with 2 10's side by side, but I went ahead and isolated the drivers, its about 1.3 cubic feet per side, minus the insulation and minus the port. Drivers a 300watts a piece. Im just in the process of calculating port hole diameters now.

OK. I'm kinda playing Devil's Advocate here, as I've not done the math for a sub myself (just a few speakers).

I'm aware that different internals can make a big difference; I'm thinking of bipole and dipole configurations vs. isolating the drivers.

If your calculations give you a box of x by y by z for one of those drivers, then fitting two into that box (with it split) probably isn't right. If you're effectively building two xyz boxes glued together then you've obviously got two of the same sub. Given my little bit of knowledge of room acoustics, I think you're often better off with two subs than one (as you can place them in the room for the flattest response). Therefore actually building two separate units may be better!

It all comes down to where you've got your calculations from - i.e. what sort of box (with how many drivers) they were intended to help you calculate.

I am aware I'm giving you lots of questions and not that many answers, but they may be useful questions!

 

[annunaki]

1.3ft^3 gross internal volume is awfully small for two 10" woofers in a vented alignment.

Most 10" drivers end up around 1.75 - 2.0 ft^3 gross internal volume before vent volume, bracing, and driver displacement has been removed.