Ok, Im Gonna Give It A Shot

definately driver dependent...would this be for the 10w7 in your sig?

 

jsut real quick....all i have on this comp is isd beta...1.5 cubes...25inches of port...26hz tune...

i'll let the experts take it from here

when i build...all i'm lookin for is a nice 43-48hz peak...lol

 

DONT follow my local shop's lead. they had a 12dub and 10dub on display, the 12 ported to 35 hz, and the 12 ported to 40 hz! they were loud, but sounded like crap.

eric

 

That's just a starting point, silly!

WinISD has to start you out somewhere, right?

Try modelling up a Cerwin Vega Stroker 15... it'll start you out with a 0.4 cu.ft. box tuned to 68hz! :lol:

It just tries to give you a friendly starting point, based on some algorithm it has.

Change it, of course. That's what the modelling software is for! :detective:



You might want to do a dual-chamber vented enclosure, if you are looking for a good, all-around "fun" enclosure, that puts real street cred over SPL-competition type bass (which, outside that tuning frequency, doesn't hit real well at all, typically).
The dual-chamber vented enclosure essentially establishes a single enclosure that has two distinct tuning frequencies.. one up high (such as 45 or 50hz) to give you that big-peak SPL-comp winning boost up around 40-50hz... and one down low, around 25-30hz, to give you the big bass as the frequencies drop (and also prevent your subs from overexcursion down there too, no subsonic filter required... or desired. B)).
Sound like what you are looking for?

 

feel free to correct me if i'm wrong anyone....this is just a theory, i am not stating it as fact...but even though the ports are the same size due to the changes in enclosure volumes and possibly other factors (traveling through the port into the other side of the enclosure) would change the tuning point of the one...which gives you the 2 different tuning points...

is this anywhere close to correct????

 

Yes, the ports and their lengths are all the same dimensions...
But the box does have two chambers, which usually have a 2:1 ratio between them.
This is what varies the tuning between the two ports.
Also, consider that the subwoofer is mounted in one chamber... so for the sound energy to escape from one port, it simply needs to exit the port, same as a typical ported enclosure. For sound to escape out the other port, it needs to travel through the center port, into the other chamber where the mass of air in effect resonates just like if it were an actual subwoofer itself... and then the air has to travel through the third port to finally exit the enclosure.

You can vary the chamber ratios, to bring the tuning frequencies closer or farther together, but typically 2:1 is what people use.

 

Safer to go below Fs?
Maybe I don't follow quite what you are asking...

You can play virtually any frequency with this type of enclosure, due to it's two tuning frequencies... near either frequency, excursion is minimized.
And no need even for a subsonic filter.

Of course, if you raise the entire system's tuning high enough that your lower tuning frequency is high enough, you might employ a subsonic filter...
But IMO (unless you narrowed the two tuning frequencies together, via chamber ratios), by the time you did that, you'd end up raising the higher tuning frequency beyond a useful point anyway.