(3) 10s vs. 2 15s

could i in theory hit just as hard with three tens as i could with two fifteens?

it depends on the specs of the speakers. what are they? the main thing is probably the colils on the speakers and how big the surrounds are. if you got big surrounds for the 10's then possibly. but at the same time it all still goes back to speaker, headunit, and amp specifications.

I use 3 4 ohm 8000 sreies MTX 10's at 1.33ohms (parallel) powered by 1500 clean watts. They hit harder than everyone I know.  And they have 12's and 15's too. Build a Great box and give them plenty of power.

If you have enough money and want to blow people away, buy the new 9500 series MTX subs. They beat the JL10w7 in all areas. You can compare them at the MTX website where they will show you full tests. You need to build a TOUGH box for them though. And they mount deeper than any other sub. I heard one at the shop and it hits HARD!

Are you comparing the 10's and 15's of the same model?  In that case, then no.  An example, a typical Sd (cone area) on a 10 is around 300 cm^2, while a 15 would be 750 cm^2.  So 3 10's would have a total of about 900 cm^2 radiating area, while two 15's would have a total of 1500 cm^2 radiating area.  So even with the same excursion capabilities (not all companies 10's have the same excursion as the 15" versions), the displacement of the 15's would be much higher. 

And as for the MTX 9500's beating the W7 in every way,  that is not true. 

Steven Kephart

Adire Audio

Below is the link to compare the JL10w7 to the MTX Thunder 9500 superwoofer

http://www.mtx.com/caraudio/headtohead/w7.cfm

Below is the link where I refute MTX's arguments:

https://www.the12volt.com/installbay/forum_posts.asp?tid=28956&KW=kephart+9500&tpn=2

Edit: Oh, and I just comment on MTX's arguments.  I could list several areas where the W7 is far superior.  And those won't be based on misleading marketing propoganda.

Steven Kephart

Adire Audio

Well my opinion is kind of bias as I work for Adire Audio.  But luckily many people who have had experience with both have backed up my opinion.  From an output standpoint, the Brahma matches the W7 in displacement.  And because of our XBL^2 motor technology, the Brahma's BL curve is just as flat as the W7's.  This means they each produce very little distortion, much less than any other driver on the market using a standard motor topology.  To back up this claim, you can see DUMAX reports of both the Brahma and W7 below.

http://www.adireaudio.com/Files/DUMAX/BrahmaDumax.pdf

http://www.adireaudio.com/Files/DUMAX/JL-10W7.pdf

As you can see, BL changes only about 1% over most of their excursion for both of the drivers.  To give you an example of the BL curve of an overhung motor like what's used on the 9500, here's a DUMAX report of our Shiva.

http://www.adireaudio.com/Files/DUMAX/ShivaDUMAX.jpg

As you can see, the BL curve is very parabolic.  This means that as the cone moves, BL drops and distortion greatly increases. 

Now there are some differences between the Brahma and W7.  The Brahma was designed for a very small enclosure.  Because of this, the Brahma isn't as efficient as the W7.  So depending on application, one might be a better choice than the other.  Another difference is the high Qts of the W7.  JL's design to achieve a flat BL curve although innovative, does have the problem of being very flux inefficient.  This can be seen by the high Qes and low BL.  The W7 also has the advantage over the Brahma of a very long throw on it's suspension.   

So in conclusion, I believe that the W7 and Brahma are equals.  Application will dictate which one would be best to choose.  If you can spare a little room for an enclosure, but  don't have much power, then the W7 might be a better choice.

Steven Kephart

Adire Audio