4- 15 inch Powerbase Extreme subs

Ok, did a search and found their homepage.  Unfortunately they don't list all the parameters there.  But I can get some ideas from what they do list. 

First of all, I doubt that sub will come close to the Brahma or W7 in SQ.  Although Powerbase doesn't say what motor topology they use, by what they say I am going to assume they use a standard overhung design.  After all, it is the most common design in this class, and I don't think they could get the "high excursion" from an underhung motor for that price.  Of course their definition of "high excursion" could easily be half the linear excursion of the Brahma and W7.  The latter drivers both use different approaches to flatten out the BL curve of the driver, which greatly reduces distortion.  Also those drivers both use a progressive spider which keeps the Cms curves flat.  The Powerbase driver uses dual linear spiders.  Linear spiders provide a parabolic curve, and using dual spiders magnifies the nonlinearities.  This is why I don't understand why a driver like this uses dual spiders. 

I plugged the numbers into WinISD, and it gave me the rest of the parameters.  I think some of the numbers on the site are fudged because I got a Qms of -.39.  But even still, I modeled the curves up comparing to the Brahma 12.  The Powerbase driver models to have horrible low frequency extention in both ported and sealed enclosures.  Sure it takes a tiny enclosure (.36 cubes sealed), but the response is horrible.  My guess is that this driver is designed for SPL, and not SQ.  I would like to know a little more about it to see if it could get as loud as a Brahma or W7. 

So in conclusion, based on what information I have I will say no, it isn't on par with the Brahma and W7.  This is because I believe they are different application drivers.  But I should also mention that I work for Adire Audio, so I am slightly bias.  But my opinion is based on objective information, so I don't think that bias is shown in my conclusions thus far.

THOSE SUBS  SOUND GREAT I SELL POWEBASE AT MY SHOP AND THEY  ARE COMPAREABLE TO W7S  BUT I HAVE  NEVER HEARD THE BRAHMA   BUT THEY  NEED BIG BOXES TO SOUND RIGHT THE DO NOT KIE SMALL BOXS AT ALL

You may wish to retract that comment, i have personally heard the models below the extreme series.. and would compare them to treo ss, w7's.. if not somewhat louder. they slam they were underpowered and in a prefab box.. lemme tell you for two 15's in a crappy box they hit like a champ. i plan on persuing a collection of 4 for my explorer.. as soon as i can get a better price than 399 a piece.. bleh.