Room gain, sealed vs ported

[TankTop]

I might be moving my system into a pretty small room and I’m running dual SVS SB3000’s. Doing some research it looks like I’ll get a huge amount of room gain below 35hz… longest wall 15’, 126 ft.² and about 1050 ft.³. In my reading it looks like sealed subs benefit much more from room gain than ported but I don’t understand why, can anyone dumb it down for me?

Don’t judge my math, it’s close enough.

 

[fpitas]

Probably because sealed subs typically don't go as low and roll off half as fast (12dB/oct vs about 24dB/oct).

 

[DonH56]

Sealed subwoofers roll off slower than ported subs below their tuning (cutoff) frequency. A sealed sub rolls off at 12 dB/octave whereas a ported design is usually 18 to 24 dB/octave, so the output drops faster below the port tuning frequency. This provides more bass below their roll-off frequency for sealed subs compared to an equivalent ported subwoofer (but typically less bass above; ported subs generally have greater output at and above the tuning frequency). The driver in a ported sub is also "unloaded" below the port tuning frequency, meaning it is no longer controlled by the box (no backpressure to reduce cone movement), and is free to flap at will. It is therefore easier to overdrive (bottom out, rattle, damage) a ported sub below the tuning frequency. Sealed subs often include a boost below the low frequency corner to extend their bass response; it is not usually practical to do that with ported subs due to risk of driver overdrive and damage. Sealed subs are also physically smaller than their ported brethren.

A pair of SB3000's in that room will be plenty loud IMO... Since the 7'3" wall is nearly a multiple of 15' you will have multiple modes (nulls) at nearly the same frequencies, so placing the subs in different locations to counter those will help even (smooth) the in-room bass response.

HTH - Don