Cascade Audio's Acoustical Cotton Composite ("Cotton Composite") was applied over the VMAX to function as a broad-spectrum sound absorber and barrier. The Cotton Composite, with its dense inner barrier layer, and its foil covering provides thermal insulation, sound damping, and sound blocking in one product. I believed the Cotton Composite was the ideal complement to the VMAX since it has an NRC (Noise Reduction Coefficient) of 0.53 at 250Hz, and essentially 0.98 or higher, at 500, 1,000, 2,000, and 4,000Hz. The Cotton Composite, available in 2-foot (609.6mm) by 4-foot (1219.2mm) panels, was easily cut with a utility knife and adhered to the VMAX or the sheetmetal substrate using heavy-duty construction adhesive (for example, ICI Paints' Liquid Nails PN LN-903) as shown in Figure 9. Figure 10 shows the interior cargo area of the Sprinter after the addition of the Cotton Composite. (See Figures 9 and 10)
Although the cargo area floor of the Sprinter hasn't yet been treated, the improvement in the acoustical environment of the van and the reduction in road noise were remarkable. In fact, recording engineers and acoustics engineers who've listened to my van have complimented its acoustics. I hope that this article, in conjunction with Part 1, has conveyed the importance of the listening room, the automotive interior in this case, and its dramatic impact on the sonic performance of an audio system. Stay tuned for Part 3 and beyond, where I'll explain the system design goals, component selection, and show detailed fabrication processes.
Resources
1. R. Harley, The Complete Guide to High-end Audio, 1st Ed., Acapella Publishing, p. 94, 1994.
2. R. Harley, The Complete Guide to High-end Audio, 1st Ed., Acapella Publishing, pp. 97-8, 1994.
3.R. Harley, The Complete Guide to High-end Audio, 1st Ed., Acapella Publishing, p. 94-5, 1994.
4. V. Dickason, The Loudspeaker Design Cookbook, 6th Ed., Audio Amateur Press, 2000, pp. 166-171.
5. R. Harley, The Complete Guide to High-End Audio, 1st Ed., Acapella Publishing, 1994, pp. 207-216.
6. P. R. Bevington, Data Reduction and Error Analysis for the Physical Sciences, McGraw-Hill, pp. 60-1, 1969.