I went to future shop to check out some of their cheaper woofers and get talking with the sales guy. He points me to a 12" MTX 6000 factory refurbished for $50. I figure for $50 how can I go wrong, also MTx recommends 1.25 cubes sealed for it and that's what I have.

It also recommends 2-3 cubes ported.

I am happy with the sub. I works well and delivers reasonable rumble. I throw the Specs into WinISD and notice that 12 cubes is good for a ported enclosure tuned to 20.5 Hz :eek: That's a far cry from the 2-3 cubes recommended! I knew that manufactures suggested boxes were often off, but that seems nuts!

The Funny thing is, is that according to WinISD this sub will work better in my car as a free-air application than my pioneer sub does. Oddly enough, my pioneer is actually called free-air, while the MTX 6000 is a regular sub.

Thought that was interesting

[ October 15, 2003, 12:52 PM: Message edited by: maltesechicken ]

Why do you get the impression from WinISD that 12cuft is 'good'? Was that the 'suggested' box?

Need to be careful of that. Often a computer suggests a box based on some arbitrary alignment the programmer put in or some criteria like maximally flat response. This can often wind up with a box that the woofer cannot even perform in due to mechanical limits or other limits.

My favorite example is the RF Pro124 12" from the early 90s. The T/S numbers on it used to cause TermPro to recommend a 0.24cuft ported box for it. The response curve was terrible and I can only imagine what it would sound like but that enclosure size fit what the math said.

Just a heads up to be careful [img]smile.gif[/img]

Oh - glad you like the 6000 woofer. They're a pretty good woofer for the $$$

Well, here's my train of thought:

The first box that WinISD came up with was 13 cubes tuned to 18 hz. That had a funny frequency response with a funny drop and bump at the end. I adjusted it to 12 cubes and 20.5 hz and the response looked resonably good.

What things do I need to watch out for with WinISD? The only things that I noticed was that the group delay topped out at 61 ms @ 19hz.

Are there other box programs that are more user safe?

Unfortunately I have yet to find a free program that models driver excursion. I really like this feature on Term1 / TermPro software. It lets you know when you are getting too big and your woofer may be getting out of control.

Other than that you have to employ some experience and rules of thumb.

WinISD Pro plots driver excursion ...

Although I'd like to get a program that's better ...

It does? lol - maybe I should use it more often eh? heh - I'll check on that tonite :D