Old School RF Box Question

[arizona]

So my friend has an old RF Punch PCH-412. The old ones from like 94 lol. Anyway, whenever I model a box up in WinISD or BB6 I end up getting a F3 of around 59-63hz :wow:

This is with designs around 1.6 @ 34hz with 25 sq inch of port area. Unless I make the box like 3.5 before displacement (just to get a F3 in the mid 30's). So what am I doing wrong here? An F3 that high just doesn't make sense... :confused:

I'm using the specs off of the RF site found here: http://www.rockfordfosgate.com/library/datasheets/pch-412_812-ts.pdf

[ramos]

It makes perfect sense considering the sub your modeling with isn't a small enclosure sub. Subs of that era relied more on efficiency rather than brute force to get loud. :)

[arizona]

Thanks lol, I've only designed a few boxes and never worked with any old school stuff like this before. I was surprised when I saw its efficiency... guess it makes sense.

So with a box that big I am going to have to increase the port area quite a bit right?