The Goal: The client was looking to achieve a flat response and high sound quality between 20Hz and 80Hz, with a bit of authority, should he ever decide to turn it up.
The Design: The vehicle that the above performance goals were to be met in was a 2004 Mercedes C230 Kompressor; not the most cooperative cabin geometry to model around but, in the end, a fairly rudimentary bass-reflex design showed to offer the overall best performance at the listening position.
The Build: This particular alignment relies on a rather narrow duct. Narrow enough to cause audible turbulence at the predicted peak velocity. Simply increasing the cross-sectional area wasn’t an option because of the various phase / resonance issues that this would have caused at the listening position. Instead, 1.5″ radius flares were applied on both sides of the port, effectively increasing it’s air volume transfer capacity just beyond the predicted peak.
For this to happen, the outer vent wall had to be double-stacked to a thickness of 1.5″. Note: Flared vents look cool–no doubt about it–but there’s a time to use them, and there’s a time when they contribute nothing to the overall system performance. (Mind your design work; flares improve performance not when an enclosure has them, but when it needs them and has them.)
The remainder of the assembly process was fairly straight-forward: Rear baffle, top baffle, woofer cut-out… With this build, I decided to use large-radius round overs along the front of the enclosure for that cross-bevel / curved inset look: