Slew-induced distortion explained

Slew-induced distortion (SID or slew-rate induced distortion) is caused when an amplifier or transducer is required to change output (or displacement), i.e. slew rate, faster than it is able to do so without error.[1] At such times any other signals may suffer considerable gain distortion, leading to intermodulation distortion.[2] Transient intermodulation distortion may involve some degree of SID and/or distortion due to peak compression.

These are effects that tend to occur only during parts of a waveform fed through audio amplifiers, that may give rise to audible degradation of the sound quality in music, even when fixed-frequency harmonic distortion tests show low amounts of distortion for a simple sinewave test signal.

TIM (Transient Intermodulation Distortion) was first discovered by Matti Otala in the 1960s due to accidentally wiring an amplifier incorrectly.[3]

References

  1. https://web.archive.org/web/20190303175101/http://pdfs.semanticscholar.org/cdbd/3ffcb276aabaf6cccd9b6bf067ee665c82d9.pdf
  2. http://www.aes.org/par/i/#IM AES Pro Audio Reference for Intermodulation Distortion
  3. Web site: Condemnation without Examination is Prejudice . Curl . John . May 2006 . Q Audio . Sacramento, California . 9 . https://web.archive.org/web/20131110011700/http://www.q-audio.com/johncurl.pdf . 2013-11-10 . dead . First, Matti Otala found, back in the 1960s, by accidentally miswiring a power amp, that negative feedback was a problem with the subjective performance of audio circuits. Otala found that when both the open loop bandwidth increased and the feedback was reduced, the amp sounded better..

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