In the P2500 manual (Rev E.), its described on page 42, but they call it Knob Bypass: "When this button is pressed and its LED illuminated, the front panel knobs are disabled. This unusual feature allows you to pre-set the knobs to a certain position in preparation for a performance effect such as a pitch or filter sweep. Without this feature, the knob might be in a inappropriate position and suddenly jump to the current value when the knob is touched, ruining your intended effect." P2500 Manual, Rev B, p. 40 P2500 Manual, Rev C, p. 42
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Re: P2500: Knob Hold button: what it does.
2014-01-29 by steve_the_composer