Stereophonic frequency test record for automatic pickup testing
Ari Schwartz, George W. Sioles, Benjamin B. Bauer · IRE Transactions on Audio · 1962
The recently issued CBS STR-100 stereophonic test record enables the user to make a rapid and accurate assessment of phonograph pickup characteristics. An important feature of the record is the synchronized sweep frequency bands which are used in conjunction with a level recorder to obtain an automatic plot frequency response and crosstalk in a fraction of the time previously required. A synchronizing circuit for the level recorder is described. Spot frequency band with voice announcements also are provided. Other test bands permit measurement of pickup sensitivity, stylus-tone arm resonance compliance, and wavelength loss based on Miller's equations. A significant proportion of the effort was devoted to calibration of recorded amplitudes. Microscopic, light pattern and variable speed turntable methods were used, and the resultant calibration curves are shown.