Cone Rocking

[AcousticScience]

How strong is this effect and how does it impact the performance of bass reflex enclosures? Is it ever severe enough to cause coil rub? I noticed in the blurb to the Simplexx designs about balancing air pressure inside the box with multiple ports. I've also read about this on other forums.

Many Martin Audio and my current compact 12" PA subwoofer designs have similar porting, mostly for strength and because I like the look. The Barefaced active subwoofer also has a port in each corner (square though not triangle) but yet there are many designs that work well with a single port, so how much difference does it make?

[Bill Fitzmaurice]

I can't say how often it occurs but since the cure is so easy there's no reason not to use it.