“AR” stands for Attack Release, which are the two stages of a simplified envelope generator used to shape the amplitude or other parameters of a sound over time. The AR envelope generator provides a control voltage (CV) signal that can be used to modulate various aspects of a synthesizer’s sound, such as the amplitude, filter cutoff frequency, or modulation depth. The two stages of the AR envelope are as follows:
- Attack: This is the first stage, during which the control voltage rises from its initial value (usually zero) to its peak value. The attack time determines how quickly this rise occurs, with shorter attack times producing a faster, more immediate onset of the sound, and longer attack times creating a slower, more gradual increase in amplitude or other parameter.
- Release: This is the second stage, during which the control voltage falls from its peak value back to its initial value after a note is released or the gate signal is deactivated. The release time determines how quickly this decrease occurs, with shorter release times producing a faster, more abrupt fade-out of the sound, and longer release times resulting in a slower, more gradual decay.
The AR envelope is a simpler version of the more common ADSR (Attack, Decay, Sustain, Release) envelope, and is particularly useful for creating percussive sounds, plucks, or other sounds that do not require a sustained or decaying portion. By adjusting the attack and release parameters, a musician can shape the dynamic characteristics and articulation of a sound, offering a range of expressive possibilities.