To modify a Sub-woofer to go down to 16 Hz or less?

Question

The Mythbusters did it, I want to do it for Experimental purposes

Answer 1

To do this you must lower the resonant frequency of the speaker cone.  This is done by softening the suspension (usually by wearing away the material) and adding mass to the cone (add layers to the cone material).

However, if you do this, you will lower the efficiency of the speaker, and unless the cone is large (18" or more), you will not get much volume out of it.  This can be compensated by using multiple speakers.

It would also have to be in a properly designed bass-reflex enclosure tuned to the new resonance of the speaker

Answer 2

A bass-reflex enclosure for 16Hz would be impossibly large. Just place the speaker in a sealed box, so only sound from the front surface is used. This halves the efficiency, so double the power of the driver. To keep the diameter down, just increase the throw. You need a flexible seal such as a Bellofram diaphragm that can accommodate the long throw, plus a speaker coil and magnet that are suitably designed. Mechanical resonance is very unlikely to be an issue, it will only limit the MAXIMUM frequency that you can produce. Of course, that is what the mid-range speaker is for.

If you just want to generate infrasound, use a Helmhotz resonator. This only works at one frequency, but is WAY more efficient for a given size. Be careful, high power infrasound is extremely dangerous.

If you want to fork over a few bucks, the ieee has a paper all about it:-

http://ieeexplore.ieee.org/Xplore/login....

But be warned - this guy wound up in a wheelchair for the rest of his life after the infrasound tore up all of his internal organs.

Answer 3

just vary the value of the resistors