Home Theater Hacks

Hack #41. Lower the Resonant Frequency of Aura Bass Shakers

Although bass shakers in their default configuration add some punch to your home theater, you can tweak the resonant frequency of the Aura models to create an even deeper shake and better performance.

I have a pair of Aura Pro Bass Shakers [Hack #40] attached to my couch. The shaking they produce is always a hit with visitors and is vital to my listening experience because my wife hates loud noises, and I love LF (low-frequency) effects. I can't crank up my subwoofer, but the shakers keep us both happy. Anyway, they normally have a peak effect in the low 60s—measured in hertz—but that's just a tad too high for best effect. Some people use bass equalization to tame this peak, but I decided to lower the resonant frequency of the shakers themselves.

It's easy to open the Aura Pro Shakers using a #20 Torx driver. Once you open them, you'll see a three-legged plastic spiral spider that supports the moving magnet/mass. The voice coil is fixed and on the periphery of the unit. To change the resonant frequency, you can either increase the mass, or make the spider more compliant.

Tip

If you're not used to seeing the word compliant in an audio context, it simply means to make something more yielding to pressure.

The legs of the spider are quite stiff; they are more than able to support the mass. Because there was little room to add more mass, I used a Dremel tool and cutter bit to trim the spiders on both speakers so that they ...