Ovation Guitar Internal R&D Test Record - Model 1687, S/N 0075 (#75)

This is an internal Ovation guitar research and development document from 1976-1977, detailing construction specifications and acoustic measurements for guitar #75 (Model 1687-8/7, Serial Number 0075). The first page records build details including top bracing weights, bridge dimensions, and notes about sound testing, while the second page contains a frequency response graph (db vs Hz) measured by technician D. Johnson on 7-11-77, showing resonance peaks and acoustic behavior across the full audible spectrum.