need to know about the Series Tuned Dual Reflex Bandpass Enclosures
if i have two focal 27h one on each end of the box with the port in the center of the box what will it do for SQ
if you do not know what i'm think the box looks like a Dual Reflex Bandpass
(6th order) Enclosure but the 2ed port goes into the other side not out the side of the box
http://www.caraudiohelp.com/custom_c...udio_boxes.htm

Decreased frequency response,less accurate reproduction,greater woofer unloading,less power handling,
I think it would boom like crazy,while sounding like poo

I'd try a quasi eighth order design if you wanted to maintain good SQ while getting more SPL out of the system.

I built one for two RE8s and it was good. Just takes time to design and build, and uses a lot of room.

http://www.diysubwoofers.org/prt/dual_chamber.htm

That will get you started, but I'd post your numbers here or on icix before you build because if i remember correctly, how they calculate the tunings on that page isnt quite right.

i hear they can sound decent, but it would have to be custom built for your woofer, using a prefab bandbass isn't a good idea

A what? [img]graemlins/freak.gif[/img]

That link is to a Dual Chamber Reflex, or ABC box.

I think he must mean a qusi 4th order? That's not what the link shows but it would be a bandpass.

it's not a 4th i'm thinking of more like a 6th order but its not a 6 .on a 6th you ports each go out the sides the one i'm thinking of will look like this a box that has 3 parts two are ported into the center that is then ported out into the car where my ski boot is i have a 1/4 firewall as the back of my seat and my ported does not work well

Tri-Chamber Bandpass Systems http://www.diysubwoofers.org/bnd/trichamberbp.htm
someing thing like this 2 SEALED, 1 VENTED SECTIONS or 3 ported in a box #1 ported into box#2 box#2 ported out(into the car) and box #3 ported into box #2 do you get it ? [img]graemlins/blah.gif[/img]

Dukk, it's ABC time. :D

Class is now in session, take it away ol'boy... [img]graemlins/thumb.gif[/img]

ok McKenzie i was looking at your box in your car it look like you have a 525 or a 535 e34 .i have the e32 735i can you send me your box plans ?

735idude - the box is still a vented bandpass (6th order) whether it the outer chambers vent into the middle one or straight out. Commonly accepted term is a Series Tuned Vented Bandpass.

Forget the whole "order" thing as it gets confusing. For instance, a sealed bandpass and a vented box are both 4th order boxes. So is a sealed box with a 12db/octave passive crossover in it. [img]graemlins/freak.gif[/img]

People are probable suggesting sealed bandpass boxes (4th order bandpass) as they are smaller, usually smoother, and generally WAY easier to build. [img]smile.gif[/img]

Focal recommends a bass reflex enclosure for these subs, they will work in a bandpass enclosure, but ..............i've never thought that bandpass enclosures ever sounded good. Great for getting a lot of output without a ton of power.
And if your'e building it yourself........beware, you gotta be pretty bang-on with the enclosure volumes....otherwise you just wasted your time.
If you want sound quality.......use a basic bass reflex (ported) sub box.......they'll sound awesome and still give you plenty of output when you want it.

Focal.., in Bandpass is a no no in my books.
Forget bandpass if sound quality is what you're after, which is why you bought Focal, right??
Listen to Dukk and Gmoney !!

See now Dukk likes Bandpass boxes but knows that most people screw them up and even done well they are not a lot of people's gig.

I would build a vented box .

I have heard good sounding bandpass boxes. But the design of a good sounding band pass usually negates the other advantages such as efficiency.

^ Ah but they look cool and every one will think you are a super-stud cuz you have one [img]graemlins/headbang.gif[/img]

Except for audio snobs with pre-conceived notions that it will sound like crap before they even hear it, thus screwing up your SQ score [img]tongue.gif[/img]