Re: Re: car audio
 
>        Yessss! Someone to brag to for a moment. [Loud Mouthed Bragging Mode 
O
> My neighbor is a composites guru for the aircraft industry. He fixes what 
the
> rest mess up and plans the new state of the art projects for them. I am a 
> woodworking fanatic. I build furniture, wall units and cabinets. 
>    A couple years ago I became fascinated with the Hsu Subwoofer design. So 
w
> put our heads together and built a kevlar composite shell rather than the 
> cardboard form used by Hsu. We used an exceptionally high carbon composite. 
W
> bowed the top to cancel standing waves and built in the platform for the 
> crossover and the tuned port. The crossover was protected by a second piece 
> that snapped into place and could be sealed with adhesive. In later models 
we
> included the flared ports in the design which cut down on turbulence noise. 
>    We ended up with some exceptionally light and strong structures that 
> sounded quite good....not high end....but much better than the commercial 
> grade powered and unpowered subs you see on the market now. 
Wow! Impressive project. I'd brag about that too! Now this is something I can
relate to. Weight is a serious drawback when trying to get decent sound in a
vehicle. I know; I'm driving around with a 45 pound particle board test
enclosure in my trunk that I'm using to try out some drivers over the road.
Again, variable volume, quick install-remove, and quick-change speaker
baffles (6", 8" and 6x9' so far). I want to look into using composite shells,
possibly thin inner-outer shells sandwiching a resonance-damping core
material. There are some people doing work with molding enclosures out of ABS
plastic (not a material I'm enthused about, for either weight or resonant
quality, but it has possibilities).
Bowing a surface is an interesting idea - have you seen Deflex panels? They
appear to use a similar approach, but on a flat panel with ridged polymer
material that produces a Fresnel lensing effect to emulate a concave
spherical surface. Expensive, but highly rated. Being an independent sort,
I'm going to do some experimentation with a router just to see how well (or
badly!) I can approximate this effect. Precisely controlling, rather than
simply damping, sound waves on the inside of the enclosure is a whole new
science with enormous potential for advances. Computers are going to be the
key for modeling new approaches.
Not familiar with the Hsu sub design - can you elaborate? Anything like the
Polk HVCD?
Glenn
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