subwoofer bandpass box questions.

[carter1010 10+ year member]

Hello all, I have some questions about bandpass boxes.

Can any subwoofer work in a bandpass type enclosure?

How do you know if a sub is optimized for use in a bandpass system?

I have an existing bandpass box that had a sub in it, is there a way to identify what size the box is and what driver would work best with it?

Thanks in advance.

Click to read more...

 

[bladebarrier 10+ year member]

Hello all, I have some questions about bandpass boxes.
Can any subwoofer work in a bandpass type enclosure?

How do you know if a sub is optimized for use in a bandpass system?

I have an existing bandpass box that had a sub in it, is there a way to identify what size the box is and what driver would work best with it?

Thanks in advance.

There are a few things that can flag it. Which woofer is it? Bandpasses are possibly the most complicated box to design, but if you post the TS, I could screen shot some results.

 

[Jroo 10+ year member]

I have the same question. I want to know what to look for to say if a bandpass will work. I was told to look at fs/qts and if below 50, sealed and bandpass work. I got these clearance woofers from a speaker builder and they said 0.5 sealed but could go band pass. Here are the specs they sent me, what do you think?

Power Rating RMS Cont. 250 Watts

Max Power Rating-Unclipped Amp 350 Watts

Freq Response 25-150 Hz

Nominal Imp 8 Ohms

Voice Coil 2" 4 Layer

FS 25.18 Hz

Qms 8.8040

Qes 0.3579

Qts 0.3439

Vas 67.30 Liters

Cms 0.3994E-03 M/N

Re 6.93Ohms

BL 17.505 Newtons/Amp

Sd 0.034636 Sq. m.

Mms 0.100017 Kg

Hvc 0.980"

Hag 0.375"

Xmax 0.303"

Xlin 0.605"

Ref Eff 0.2885%

Predicted Output 86.802 DB/1W/1M

I have 2 tens and was thinking 4th order wired to 4 ohm load.

 

[carter1010 10+ year member]

the sub that was in the bandpass box was JL 12w3. It was not made for this box, someone had a bandpass box and threw a W3 in it. The box demensions are 9.5 x 13 x 13 sealed side, and 15 x 13 x 13 ported side with two 4" x 7" diameter ported boxes. I know its a generic ported box, but its a pretty nice enclosure and I would like to put an appropriate driver in it.

Thanks again!

 

[carter1010 10+ year member]

That comes out to .9 cuft on the sealed side and 1.5 cuft on the vented plus the 4" x 7" tubes. Any suggestions as to how to figure out if a sub will work in this. Leaning towards an RE but not sure if they will work. Suggestions please?

 

[skylineTT 10+ year member]

dont weaker subs generally benifit from pre-fab bandpass boxes? my 2 Type R 12s that i just bought came in a Qlogic BP and it sounded whack. i figured some cheapo 12s would be better though if i decide not to sell that box..

 

[vellocet 10+ year member]

dont weaker subs generally benifit from pre-fab bandpass boxes? my 2 Type R 12s that i just bought came in a Qlogic BP and it sounded whack. i figured some cheapo 12s would be better though if i decide not to sell that box..

You build your box for your sub. A sealed box is pretty easy to match up, the more complicated it gets, the more difficult swapping drivers is. With a bandpass the type of driver changes what kind of sound you get Alot. Pull up winisd and play with it some. The box can be designed for output or make relatively flat sound.

 

[skylineTT 10+ year member]

yeah i get that stuff, but i was just under the assumption that most pre-fab, best-buy, bandpass boxes are made so that low end subs can get louder. a sub with a lot of displacement and power wont generally do as well in those boxes as the lower end subs do. i know BPs can be made to make beefy subs loud as well, i was just talkin about those pre-fabs.

 

[bladebarrier 10+ year member]

yeah i get that stuff, but i was just under the assumption that most pre-fab, best-buy, bandpass boxes are made so that low end subs can get louder. a sub with a lot of displacement and power wont generally do as well in those boxes as the lower end subs do. i know BPs can be made to make beefy subs loud as well, i was just talkin about those pre-fabs.

Band pass boxes are usually the most efficient wattage wise, for almost any speaker (but they're very large). The trick is that some speakers do better in them than others. You also compromise the lowest bass to do it. They're also complicated to design, and no pre-fab will be any good, unless some random luck allows that to happen.

Band pass is probably the hardest to build, as well, aside from transmission line, so a pre-fab could have all sorts of problems with it. On top of all of that, a pre-fab will generally have inadequate port quality, and some subs might literally tear the box apart, or will tear themselves apart, due to incorrect tunings.

Essentially, you design a band pass after lots of double checking of all the math. You can't just put a woofer in a bandpass and expect it to sound good, let alone not rip itself apart.

Jroo, I'm working on your specs. I should have time to sort it today or tomorrow.