Brahma 15

The guy from the local shop is just pissed you didn't give him the money.  Ignore him.  Instead learn an enclosure design program and estimate your results with both drivers. 

Actually, I just pulled up the IDMAX against a Brahma 15 in WinISD pro.

Brahma handles 1600w.  IDMAX handles 1000.  At these wattage ratings they produce very similar SPL levels through much of the bass frequencies.  However, the Brahma 15 gets much lower, rolls off slower, and stays cleaner. 

I'd keep the Brahma.

Yeah, anytime someone says something like that you have to ask yourself if they are trying to sell you something.  If they are, then ignore them.  Especially if they don't back up their claims with facts. I can provide some facts that will contradict that salesman's claims.

I also want to add that WinISD isn't very accurate.  Even their enclosure sizes can be off.  So I wouldn't trust it to show which is better.

Steven Kephart

Adire Audio

Actually for what you describe it should be just fine as a learning tool.  But just as long as people understand that the enclosure sizes, actual real world curves, and port lengths aren't right.  I just recently did a sub where WinISD said it's .707 enclosure was 2.95 cubic feet.  We then checked it in LspCAD and found out it was only 2.47 cubic feet for that alignment.  That is a decent amount to be off by.  And we have checked LspCAD many times and have found it to be highly accurate.  Although it is kind of pricey. 

I believe there is one free program that is more accurate, but I can't remember what it is.  I will find out tomorrow what it is and let you know.

Steven Kephart

Adire Audio

Steven can you give me the exact dimentions that will be perfect for this sub (i want to put it in a ported)

Thanks

It really depends on what you want out of it.  We provide a paper with several enclosure sizes for different results here: http://www.adireaudio.com/Files/cut%20sheets/Brahma%20Sales%20Brochure.pdf

Steven Kephart

Adire Audio