MTX 9512-44

I recently purchased an MTX 9512-44. I will be pushing roughly 1000 to 1200 watts to this sub. I want to be streetable but also be able to pull out as much SPL as possible from this single twelve.

Anyone have any suggestions on box needed for this? I've been toying with either vented or 4th order bandpass.

Heres the parameters on the sub:

https://www.mtx.com/caraudio/products/manualsQuickInstall/subs/TechData_T9512-44.pdf     

Here's a couple of workups so you can see a visualization of the difference in vented and 4th bandpass for this sub.  Jeff raised good points, as always.  This is designed as an inefficient woofer and needs a lot of power, and the box has to be super strong.  The extra support built into the Jackhammer box would take a load off the front baffle, but you could build one if you have experience building boxes.

This first file shows what should probably be the vented response of the Jackhammer box in the color purple.  You see that F3 hits at about 27 Hz (pay no attention to the high end;  the parameters didn't include the value Le - not necessary).  The box net volume after bracing and driver displacements is at 2.5 cu ft.

The teal line represents a 4th order bandpass that I worked up.  You see that although you can gain 2 - 3 decibels in SPL, the response for "streetability" is compromised...it wouldn't sound musical.  But if may pass, depending on your preferences and who you want to out-boom.  The chamber sizes are net, so you add port and driver, etc. displacements:

t9512-44boxsize.jpg

This next one shows vent sizes.  You can alter vent opening size but keep the same square inches for the given vent lengths:

t9512-44ventsize.jpg

This is a pretty good sub for use in this type of bandpass.  You still get a decent low end.  And I should note, for GP sake, that the overall gain in db's with the bandpass will surpass +2 db (over the vented) by quite a margin when you factor in the cabin gain, since this is peaking at 50 Hz.  You can't see that on paper, though.  If you want to compete in SPL with it, build another version of this bandpass altogether.  It would have a larger front (port side) chamber and shorter port length.  You'd have to do some experimenting with that but you could probably go as big as 4.5 to 5 cu ft in that chamber, with the port being only a few inches long.

Well heres MTx's recommendation:

Internal 3.3cu.ft with a vent 50 square inches with a length of 9.65". This gives an F3 of 33.5Hz

We are probably going to use this box, built with 3/4" mdf, double faced, and alot of bracing. The guy who builds my boxes for me, mentioned using a type of steel rod for extra bracing.

MTX stated that this sub would not sound good at all in a bandpass. I want good sound, but my main goal is SPL. I know its not going to sound the best, but it will be LOUD.

blackmica3 wrote:

---

Well heres MTx's recommendation:

Internal 3.3cu.ft with a vent 50 square inches with a length of 9.65". This gives an F3 of 33.5Hz

---

That does not sound like a winner.  Get another opinion.  When you have a peak in the response that shoots up into the stratosphere at +10 or so decibels, the term "F3" becomes a moot point.  It's the tuning frequency (Fb) that you should concern yourself with, and keep the peak no more than +3 db's if you want something that you can call "good sound".

As you described the box here, the tuning freq is at about 50 Hz.  Keep in mind that the driver unloads under Fb, so getting anywhere near that proposed 33 Hz F3 will never happen.  You will have to put a high pass filter on that at above 40 Hz, and the steeper the slope, the better.