Innovation in car audio is tricky; most ideas have already been tried. Even so, creative shops have to differentiate themselves from the crowd. One of those innovators, AVC in Stillwater, OK, created something different in a 2007 Corvette Z06. Not wanting his ride slowed down by heavy audio gear, the owner mandated that the entire system weigh less than 110 pounds. His previous system in an 2006 Z06 weighed over 200 pounds. That equals a loss of over 30hp (the Z06 has an average of 1hp per 6 1/2 pounds), which is significant for a speed freak. So this system required a serious diet. Since the equipment remained unchanged, the weight had to come off the enclosure and amprack.
To build a strong, lightweight enclosure, AVC used plastic. Using a process called thermoforming, a plastic sheet heated to over 400F was draped over a mold. Then, a vacuum was applied to pull the plastic tight, creating a hollow plastic tub that would become the enclosure.
Despite the simple process, there is an art to the science. Draft, negative returns and plastic thinning must be taken into consideration. In order to get a box that wouldn't buzz and flex, the plastic used is 0.325"; that's over 5/16" thick. Also, the design itself must have strength-inducing characteristics such as ribs, opposing angles and rounded corners, in addition to few flat areas.
Building the mold poses problems as well. The overall dimensions of the enclosure will be over 1/4" larger all around, so the tool must be smaller than the actual part. Also, the plastic has a natural roll over the corners, a detail the design must incorporate.
Since the enclosure was too large for AVC's thermoforming machine, Kicker offered theirs. Special thanks go to Joe Gross and John Cronin for their assistance.
While the plastic has a nice grain pattern that could be left as is, AVC sanded smooth and painted the enclosure, finishing it with custom airbrushing. Once completed, the system weighed in at a svelte 106 pounds. Not bad considering the amps alone weigh 22 pounds each!
The process detailed here should satisfy your curiosity and hopefully spawn more creativity with this rarely seen process in custom design. Just remember: plastic is fantastic!