Intermodulation Distortion Analysis as Applied to Disk Recording and Reproducing Equipment

Measuring the sidebands generated due to non-linearity when using a test signal consisting of two different frequencies has been found to be a useful way of analyzing distortion in disk recording systems. The method is more sensitive than the single-frequency harmonic method and gives results which seem to agree very well with listeners´ observations. Tests made at various groove velocities with playback tips of different sizes show the expected increase in distortion at the lower velocities with the larger tips. The importance of a good fit between stylus and groove is illustrated.