Crunch 12" data crunching

After looking at the price of the JL Stealthbox I decided to build my own using an old Crunch 12 I saved from the old days. 

It is a Crunch CR12WTP-04

Fs 22  QTS .28    VAS 9.25     QES .29   QMS 9.2   XMAX .261   EFF 95    RMS POWER 250W  

DCR 3.6

I bought this sub around 1995 and that is all the specs that it came with.  I know this sub is designed for a vented enclosure but can't remember the intended box volume for a vehicle.  Can someone run the numbers for me?

Play around with WinISDpro, free enclosure design software. 

Tried that.  What it gave me wasn't accurate.  

It asks for more specs than I have and everything is metric. 

It gave me a vented volume of 2.8L  That can't be right. 

OK.  It took me a second to get my head screwed on right.  I forgot to convert Vas from cu ft to liters. 

That gives me a ported volume of  78.9 liters which is 2.78 cubic feet. 

YIKES, kind of big. 

Can anyone plug the values in to see if you come up with the same thing?

Yep, just did.  To get a workable port size and decent bass extension, that woofer wants a box size up to 3.2 ft^3.  A good enclosure can be made at 2.85 ft^3 (net) with a 3" x 11.5" port, tuned to 22 Hz.  But I guess if you were looking at a stealthbox you might want to work with something smaller lol.  You can work out an enclosure at a somewhat smaller size but watch the sub-bass disappear.

BTW, just place the cursor over the liter symbol and click through to change to different measurements.  The program does the conversion for you.

Cool.  Not used the software much.  This is an old woofer with little use on it.  but it seems it is more suited for the house.  I pluged in the value for 2 cu ft box and the port size was huge and the 3db down rolloff was around 45hz.  Kind of kills the performance of it. 

BUT, for all practical purposes, can you get down to 22hz  (real world) inside of a Grand Cherokee?

Hey Dr. Righteous, your sig is: "Real High Fidelity........ or forget it."  That woofer is a Crunch.   I'd say you'd better forget it.  :)

But yes, the numbers in the messages above are correct for the T/S data you provided.  Not a very good looking performer on paper.

DYohn] wrote:

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p>Hey Dr. Righteous, your sig is: "Real High Fidelity........ or forget it."  That woofer is a Crunch.   I'd say you'd better forget it.  :)

But yes, the numbers in the messages above are correct for the T/S data you provided.  Not a very good looking performer on paper.

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It is one of the old ones made by Audio Products.  Back when Crunch made some pretty descent woofers. 

Reminds me of a story,

(Flashback sequence begins)

A buddy of mine wanted to build a 18" sub for house.  He bought a 18" Eminence sub and proceded to build the ported encloure by the book.  When I saw it I busted out laughing.   It was literally as big as a refrigerator.  He had it crossovered at 80hz and it shook the house.  BUT, the bass coming from it was unimpressive.  It was tuned down to like 18Hz.  We decided that the room was too small to appreciate what it would do.  Only trouble was the rest of the rooms were smaller.  So we took it outside.  He cranked it up and it sounded GREAT.  The neighbors across the street started coming out of their house.  We didn't think we was disturbing the peace.  It wasn't all that loud.  We then realized that the sub was rattling the glass in the windows across the street!    COOL, but the sub was impractical.  It took up too much room and was good to simulate earthquakes but that was about it.  He built a 12" sub and was much happier with the results.