2 10" box

[peterparker]

looking to make my own box
i loved the sound of my buddies 12" single bandpass (enclosed)

now ive got two ten inch subs ive had since i owned my 200sx, and they pounded really hard with a ported box

now im looking for ideas to build a dual bandpass (enclosed)
box.

thanks

[Graham_A_M]

Bandpass boxes are an interesting animal within themselves.
They were first created by Bose in the early 90's as a way of controlling a subwoofers frequency response without the use of a crossover in commercial/pro audio applications.
When carefully designed, they create a frequency "band" that they can only produce sound in, hence their name: bandpass.

That comes at a double edged sword. The bigger the "band" (as in a wider variety of frequencies) comes at the expense of efficiency. Higher efficiency comes at the price of having a much smaller window of sounds the sub/box can reproduce. Basically, the smaller the internal chamber (the plexiglass portion, where you can see the subs face) the more efficient the sub will be, but VERY monotone sounding. The bigger the sealed portion, the less efficient but more diverse sounding the box will be.

So for "ideas" you need to take that into honest account.
Unfortunately, the design principle bandpass boxes work off of: is distortion. Its been probably 10 years since I was heavily into audio, so I forget the exact technicalities that that style of box works on. But I can honestly say that the subs will absolutely *NEVER* sound as good, clean and musically accurate as they would in a properly designed ported or sealed enclosure.
If you were to build a (so called) perfect bandpass box, and compare that to a perfectly designed sealed or ported box, you'll always pick the sealed/ported from a sound quality perspective. I dont know about you, but I love musical accurateness, and differing sounding bass. Not just the same monotone boom boom boom, regardless of the song or genre. :dunno:
I have some subwoofer box designing software on my computer, so I can design the perfect box for the sub in question, but you need to make a call as to what you're after from a performance standpoint.

EDIT: Oh yeah, I forgot to mention, through their design, its theoretically impossible to have a band pass box reach the ultra-low frequencies that a sub would hypothetically reach if it was placed in a specially designed sealed or ported box. With bandpass boxes, you'll never reach below 40hz, without compromising incredible amounts of efficiency.

[///LOUD LOAD\\\]

Do not bother making a bandpass for low frequencies unless you have a huge amount of volume you want to occupy. In any "regular" install a ported enclosure will out perform bandpass hands down. On top of that bandpass needs alot of testing and tuning time to perfect, not as simple to get right as simple ported.

[Graham_A_M]

^ Yeah... I should have said the only other alternative is to have an absolutely gi-normous box. By HUGE, I mean, taking up a good portion of a van even.

Band pass is seriously, not the way to go. But considering it was designed by Bose, should we really be surprised?
Dunno where the OP is, but if you give me the make & model number of the subs I can probably design a wicked box for them. :dunno:

[peterparker]

thanks for the awesome responses guys
and you've made some huge points that never truly occured to me.

these are the subs i have

polk audio 10" mm2104 i believe. 2 of them.

[Graham_A_M]

Alright, I went to the PolkAudio website, and grabbed whats known as the subs "T/S (Thiele & Small)" Parameters, and dorked around a little bit with the program. The best sounding, lowest hitting & most musically accurate box is this:
45 liters per sub (*NET INTERNAL VOLUME, dont forget to workout the volume loss from the sub & the port)
with a 2" port (per sub) thats 5.10" long.

So obviously, 45 liters times 2, along with two 2" ports that are 5.10" long

The F3/3db downpoint will be at a very low 40hz. These are surprisingly good subs you have. Quite impressed:thumbsup:
These will work best in a ported box. With a sealed box, you'll lose a lot of the deepest bass that these subs can produce.

[peterparker]

so if i roughly understand that correctly
i want a ported box that is
about 1.59 cu ft=45 liters

so 1.25 ft x 1.25 ft x 1.1 ft + 2(2*5.10) +2(9 1/16"x5 1/2"x 6 1/4")

so losing 10.2 liters for the subs

and .668 liters for the ports

for a total of 100.868 liters for the box

so basically ive figured out a box size of 24x16x16

[Graham_A_M]

How do they sound?