 The exterior of each of the...  The exterior of each of the enclosures was contoured with substantial amounts of fiberglass composite comprised of chopped mat. Final shaping was done using Evercoat's Tiger Hair fiberglass-reinforced filler and Rage Gold body filler. The final wall thickness of the fiberglass composite enclosure varied from 15 to 32mm (0.591 to 1.26 inches). The largest possible pieces were cut from Cascade Audio's Deflex PowerPads and adhesively bonded to the inside of the enclosure. |  Klean Klay was sculpted to...  Klean Klay was sculpted to create molds for the A-pillar trim pieces. The front edge of each trim piece was knife-edge shaped to properly rest in the damped v-groove at the front of the A-pillar, and the rear edge of the trim piece rested against the rubber door gasket for improved isolation. The trim piece was clamped tightly against the A-pillar to resist rattling and vibration using one countersunk M4 socket head cap screw (see Figure 16). |  A combination of binding posts,...  A combination of binding posts, spade lugs, and angled banana plugs, all from WBT (see www.wbtusa.com) were used to connect the loudspeaker cables to the monitor. This cluster of connections fit below the dash in a cutout originally designed for the OEM loudspeaker. Loudspeaker cables were Kimber Kable's 4TC (see www.kimber.com). The red and white colored conductors correspond to the tweeter's positive and negative terminals, while the blue and black colored conductors correspond to the midrange's positive and negative terminals. |
 View of the completed passenger-side...  View of the completed passenger-side front monitor. The loudspeaker grille is removed to reveal the details of construction. The front-mounting baffle plate was CNC-machined from 6.35mm (1/4-inch) thick steel and coated with a black oxide treatment. To better align the acoustic centers of the loudspeaker transducers, Dynaudio's MD130 tweeter was mounted behind the plate, while Dynaudio's MW150 was mounted in front of the plate. All of the M4 stainless steel low-head socket head cap screws were recessed into counterbores to minimize diffraction. The screws secure the steel baffle plate to a constrained layer damping material placed between the plate and the enclosure. The steel baffle is recessed into the enclosure to provide a smooth transition from the plate to the contours of the enclosure, all of which possess radii greater than 50.8mm (2 inches) to minimize the effects of diffraction. The improvement in soundstage imaging due to properly contouring the monitors was simply stunning. The wall thickness of the fiberglass composite enclosure varied from 15 to 32mm (0.591 and 1.26 inches), and weighed in excess of 106 N (24 pounds) each. |  Speaker grilles were fabricated...  Speaker grilles were fabricated from 9mm (0.354 inch) marine plywood and perforated-steel sheet, which had an open area of 79 percent. The perforated steel was adhesively bonded to the marine plywood, which had generously beveled edges. Cylindrical rare earth magnets, adhesively bonded to the back of each speaker grille, allowed the grilles to be readily attached or detached from the monitors without tools. The grilles were covered with black grille cloth and a small Dynaudio logo was bonded to the lower front edge of each speaker grille. The grilles were designed mainly to protect the loudspeaker transducers from damage and should be removed for critical listening sessions. |  View of the completed passenger-side...  View of the completed passenger-side front monitor with the loudspeaker grille magnetically attached. |
Image Is Everything
Many of you may question the rather analytical approach I took in building the front monitors, apparently giving less importance to aesthetics. Some will question whether the visibility out of the van was compromised. I can assure you that plenty of visibility still remains. Still, others would think the front monitors are simply ugly, too "in your face," and would not have them in any car regardless of how they sounded. Ben Oh's "Driver's Seat" column in the Aug. '08 issue of CA&E titled, "Car or Audio," addresses this topic brilliantly. And lest you think I'm crazy, I agree with most of you that the monitors I fabricated in this article are rather imposing and bulbous. But wait until you hear how they sound; I think you'll be floored. Recently, I attended, exhibited, and demonstrated at Mr. Marv's barbecue.11 At the barbecue, I met a person who was captivated by my obsession for fine craftsmanship and the sound of my system. As I explained the choices I made during the creation of an audio system dedicated purely to serving the music, I poked fun at the whole cargo van idea and especially the stamped-steel wheels. I laughed when I said I could've purchased a very expensive Bimmer with the money I used to build my van. His reply was, "With sound like you have, I'd take your van any day!" I really liked that guy. Finally, I'd like to acknowledge and thank renowned audio component designer Steve McCormack for contributing his expertise and guidance during the loudspeaker transducer placement and aiming process. Please stay tuned for Part 7, where I'll continue the fabrication process with the door-mounted woofer enclosures.
Resources
1. F. A. Everest, The Master Handbook of Acoustics, 4th Ed., McGraw-Hill, p. 236, 2001.
2. V. Dickason, The Loudspeaker Design Cookbook, 6th Ed., Audio Amateur Press, p. 105, 2000.
3. V. Dickason, The Loudspeaker Design Cookbook, 6th Ed., Audio Amateur Press, p. 113, 2000.
4. V. Dickason, The Loudspeaker Design Cookbook, 6th Ed., Audio Amateur Press, p. 112-116, 2000.
5. V. Dickason, The Loudspeaker Design Cookbook, 6th Ed., Audio Amateur Press, p. 99, 2000.
6. V. Dickason, The Loudspeaker Design Cookbook, 6th Ed., Audio Amateur Press, p. 108, 2000.
7. V. Dickason, The Loudspeaker Design Cookbook, 6th Ed., Audio Amateur Press, p. 100, 2000.
8. V. Dickason, The Loudspeaker Design Cookbook, 6th Ed., Audio Amateur Press, p. 101, 2000.
9. V. Dickason, The Loudspeaker Design Cookbook, 6th Ed., Audio Amateur Press, p. 102, 2000.
10. F. A. Everest, The Master Handbook of Acoustics, 4th Ed., McGraw-Hill, pp. 409-414, 2001.
11. See http://community-2.webtv.net/MarvsPlace/MarvsPlace/index.html