Michael Yee Audio
Testing of amplifiers has changed very little over the decades of audio technology. The modern-day tests which measure the "quality" of audio circuits (THD, Frequency Response, noise) has proven to be of less value when determining the sound of an amplifier. One of the reasons for this is due to the simple waveforms utilized by measurement instrumentation. In fact, most tests are done with a single sine wave. One thing that we know about music is that it is never made up of a single sine wave! Mike Yee has spent a lot of time developing methods to determine the quality of an amplifier's ability to pass a complex waveform. One of the things he has learned about distortion measurements has to do with the nature of music and sounds.
Music and natural sounds have a characteristic that higher frequencies components have lower amplitude. When these smaller high frequencies are mixed with larger low frequencies, a slight distortion of the lower frequency can completely change the character of the high frequency signal. For example, if 10 Volts at 60 Hz were mixed with .1V at 3kHz, and the 60 Hz signal had 1% distortion (or a .1 volt distortion component), then the distortion from the 60 Hz signal would be as large as the 3 kHz waveform! This can completely change the audible character of the 3 kHz waveform.
It would be unrealistic to try to make a distortionless amplifier so we used another approach, so MYA focuses on ensuring that distortion components do not affect the sound of the smaller signals. This is a difficult task, and requires a lot of knowledge about how the ear "hears". Only listening will determine how well they have accomplished that task. Mike Yee feels that he have done a tremendous job!