All of our hardware brands have multiple units that specify their frequency response. The concepts of frequency response, frequency range, audible frequencies, how frequency relates to musical notes, etc. are absolutely central—critical—to understanding how audio equipment makes, reproduces or records sound and how that sound is related to the live sound produced by singers and instrumentalists.
In some cases when connecting a sustain pedal to a keyboard, the pedal may act as though it is reversed. The sound will sustain when the pedal is in the open position and will stop sustaining when the pedal is pressed. The M-Audio SP-2 professional piano style pedal ships with a polarity switch built directly into the bottom of the pedal for an easy and fast fix for these type of symptoms.
This article walks through the typical causes of a pedal sustaining when in the open position, as well as the easy fix for the M-Audio SP-2 and how to adjust the polarity for most other sustain pedals on the market today.