Kaman tested different glass-reinforced materials and settled on a construction for the first roundback guitars consisting of two layers of 16-oz 1583 E-glass supplied by Hexcel (Stamford, Conn.). Engineers “tuned” the material to enhance its musical resonance, and Ovation markets the patented material under the registered trademark Lyrachord. The glass fabric layup was bagged in a mold and infused with epoxy under vacuum, then it was attached to a more conventional spruce soundboard and wooden neck/head stock. (The spruce soundboard is reinforced on the underside with a “fan bracing” pattern the company calls Quintad.)
Today, Ovation uses three designs and manufacturing processes to produce six bowls that are incorporated into its series of 19 commercially available roundback acoustic/electric guitars. (All Ovation guitars come standard with an electronic pickup and onboard preamp; they are available as acoustic only on a custom-order basis.) The first is a modified version of the original bowl that employs wet layup of two layers of 16-oz 1583 glass sprayed with a polyester resin. The second bowl design is compression-molded polyester sheet molding compound (SMC). The third bowl comprises four layers of an 8-oz Hexcel 7781 E-glass prepreg and DA-409 epoxy resin from A.P.C.M. LLC (Plainfield, Conn.) cured in an autoclave at 250°C/482°F. The company began using the autoclave process around 2003 on newer, high-end models to achieve a more aesthetically pleasing exterior surface finish. For all bowl designs, the target nominal wall thickness is 0.43 inch/10.92 mm.