95Probite

hi guys! im having questions on Qtc.
now for starters i will be building a sealed box for 2 pioneer premier subs, BUT these numbers are only for 1 sub and 1 box. i will just double it later. now the pioneer site recommneds a ("Low-Q design and 0.6 cu.ft) simple enough, right? BUT some people have said, expereinced guys, to go with a Qtc.of .707 . they had said that is kinda the norm to go with. but if i go with that number, a HIGH value, and it makes the box smaller at 0.364 cu.ft, INTERIOR. (i'm supposed to have a final result of 0.364 cu.ft, after the displacement is accounted for if using .707).

now after calculating at a .5 Qtc, a LOW value/Qtc., it does make the box bigger at 0.85 cu.ft , after the displacement is accounted for.

and at .577 Qtc it gives me - 0.573 cu.ft

my specs on my sub and that i used are these -

Fs - 25
Qts. - .28
VAS - 1.86 cu.ft
Qtc - will be either .5 OR .577 OR .707

any thoughts? which out of the 3 should i go with ?? thanks!

Starterwiz

It depends a lot on what you have for midbas drivers. A higher q box will have more impact in the upper bass notes, at the expense of a loss of low frequency extension. Drums will be tighter, stuff like heavy metal will sound a bit better.
Lower q boxes will have more rumble, but be a bit looser.Sound good with Floyd and the like.
.707 is recommended because the woofer's response is flat down to the roll-off point. Higher q will have a pit of a peak above the roll-off, and will drop at a bit more than 6 dB/oct.
Lower Q will start dropping a bit before the roll-off, and will roll-off at a bit less than 6dB/oct.
The bottom line is a trade off....where do you need the extra dB? at 30hz, or 80hz
The only real way to tell is to try a couple of different ones...does your local shop have a box you can try? Or else build it large, and then drop some 2x4s inside to remove some air.