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RE: Slew rate, TIM hogwwash


Thank you for a plausible explanation of your theory that TIM is a non issue in modern (post some time in the 70's) transistor amp design. As to evidence contra to this, Otala (and others) published two JAES papers addressing this: 1. Threshold of Audibility of Transient Intermodulation Distortion (in 1978); and 2. Psychoacoustic Detection Threshold of Transient Intermodulation Distortion (in 1980). In the first paper a group of six of the most sensitive subjects (from a previous test of 68 listeners) were tested and it was found that "The results show that in certain passages of music, 0.003% of distortion is clearly audible". This was followed by ""Low distortion values were perceived only as changes in the sound character, and not as distortion" which could possibly provide somewhat of an opening for your position. The second paper described further testing with improved test equipment and conditions. Otala has provided test results and data to support his assertion that TIM is audible. Another google search by me with the subject "transient intermodulation distortion+audibility" didn't turn up anything saying that TIM is not audible in modern transistor amps, but to be honest I stopped reading after 30 references. There is ample evidence that TIM is audible, but anyone is welcome to make a case for whether or not it's it's an important a concern in modern solid state amp design.


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