DIY subwoofer question...
I currently have an Adire Shiva 12" sub mounted inside of an 88.5 liter sealed enclosure (Q=0.6) that was originally used for an equal amount of music and movies. This design worked very well for both however, it did lack a little punch when it came to movies. After some remodelling, my current set-up will now be used almost entirely for HT and I am hoping to add some of the punch back to the sub by building another box.
My question is, would I be adding more "punch" to my HT bass if I went down to a 54 liter sealed enclosure with Q=.707?
Many thanks!
Ports extend frequency response -- that's not what you want
Porting a 12" Shiva driver requires a specific-sized enclosure and port -- the port tuning frequency is selected based on measurements of your driver (you should not rely on printed specs.). This is a complex job. The result would be extra output under 30Hz.
That could increase the impact of explosions in action movies. It would have little effect on four-string bass guitar and kick drums.
If you want more impact from bass instruments such as kick drums and bass guitars, then you must increase output above 40Hz. A high Qtc sealed subwoofer will do that.
I built a sealed Shiva 12" sub in 1999 using a 1.7 cubic foot enclosure (internal size) stuffed with three lbs. of polyester pillow stuffing (three bags). It provided high impact bass guitar reproduction. However output under 30Hz. was weak. That was not a problem for playing music where there's little output under 30Hz. ... and that's exactly what the subwoofer was designed for.