A NEW METHODOLOGY FOR AUDIO FREQUENCY POWER AMPLIFIER TESTING BASED ON PSYCHOACOUSTIC DATA THAT BETTER CORRELATES WITH SOUND QUALITY
D. Cheever · 2001
A NEW METHODOLOGY FOR AUDIO FREQUENCY POWER AMPLIFIER TESTING BASED ON PSYCHO-ACOUSTIC DATA THAT BETTER CORRELATES WITH SOUND QUALITY. By Daniel H. Cheever University of New Hampshire, December 2001 There exists general agreement that the commonly accepted test and measurement protocols for audio frequency power amplifiers fail to correlate with the subjectively accessed devices sound quality. A review of the history of audio testing was undertaken to reveal if prior art has produced tests that better correlate with sound quality. A universal concept emerged, one that calls for stronger weight of the higher order, more aurally discordant harmonic distortion products, over the low order, more benign harmonics. Separately a study of the psychoacoustics of the ear resulted in a mathematical derivation of the ears intrinsic aural distortion. The two are combined and offer a methodology for weighing the harmonics based on a dimensionless figure of merit that quantifies the amplifier’s harmonic distortion envelopes departure from the ears aural masking, named Total Aural Disconsonance or T.A.D. It is shown both analytically and through actual device measurements that the application of negative feedback, regardless of level, results in poorer T.A.D. figures. Two amplifiers of opposing standard measurement results are fully tested and subjectively analyzed and results show that the T.A.D. method outperforms classic T.H.D and I.M. for characterizing amplifier quality. ix