I had been waiting for years to build something like this, but
it is frankly not appropriate for an apartment. As soon as I
moved in to the garage however, I wanted to whip something up asap.
This is the cannon I built over a weekend with my friends Abie
Flaxman and Rob Aimi. We used a crap-ass 12 inch driver my
friend JD had and a length of sonotube from Home Depot. We powered
the driver with an old receiver.
Most of the effort that weekend went towards measuring the
characteristics of the resulting speaker and not towards
actual construction.
For testing we hooked a signal generator up to the receiver
and scanned through 10-200 Hz manually. We then hooked a good
microphone up to an oscilloscope and used the RMS measuring
feature to gauge the magnitude of the speaker output.