I decided to construct the enclosures from solid cherry (hence the name SC 5.1) since I don’t like working with veneers and wanted an enclosure that was unique. This project could also be produced with 3/4" MDF, although I would suggest using a hardwood for the internal braces. The tweeter is self-contained and is attached to the top of the enclosure. The midbass is the only speaker “inside” of the enclosure, so the volume of the box results from the characteristics of the Hi-Vi M6N.

• Free air resonance frequency of the driver (Fs) = 46 Hz
• Total Q (ratio of reactance to resistance) of the driver at Fs (QTS) = 0.45
• Compliance (VAS) = 0.63 cu. ft.
• XMAX = 3.5mm
I selected a QTC (total Q for the speaker system) of 0.9 for the enclosure design. A value of 0.9 should result in accurate sound reproduction. The remaining values can be calculated.
• Compliance ratio (A) = ((QTC / QTS) x (QTC / QTS)) - 1 = 3
• Resonance frequency of the closed box (Fc) = (QTC x Fs)/ QTS = 92 Hz
• Box volume (Vb) = VAS / A = 0.21 cu. ft. = 362.88 cu. in. (optimal value)
Finally, WAF (Wife Approval Factor) = HIGH, therefore, the enclosure dimensions had to be as small as possible. • Internal = 7-1/2" (W) x 6" (D) x 10" (H) = 450 cu. in. = 0.26 cu. ft.
• External = 9" (W) x 7-1/2" (D) x 11-1/2" (H)
• Volume occupied by internal braces (estimated) = 66 cu. in.
• Internal volume (450 cu. ft.) – volume of internal braces (66 cu. in.) = 384 cu. in. (384 cu. in. = 0.22 cu. ft., close enough to the 0.21 cu. ft. optimal value)