A hardware plate reverb creates reverberation by bouncing sound off a metal plate. The Korg M3 plate reverb effects simulate this effect. Plate reverbs don't spread the sound out as much as other types of reverb: use a plate reverb to add richness to vocals and synthesizer leads without burying them in the mix. The M3 includes both a wet and a dry plate reverb; the wet reverb affects the sound to a greater degree than the dry plate reverb.
Room reverbs recreate the sonic environment of a room. Change the settings on the Korg M3's room reverb to emulate different room shapes and sizes. Use a room reverb when you want to add some space to a sound without moving it too far into the background. Guitar tracks, for example, often benefit from room reverb. The Korg M3 also includes a "BrightRoom" reverb that, as the name implies, creates a brighter sound than the normal room reverb.
A hall reverb emulates the ambience of a larger space such as a concert hall, church or arena. Use Korg M3's Hall reverb to create the sound of a medium-sized space; use the SmoothHall effect if you want to simulate a large space. Hall reverbs move sound deep into the background of the mix; apply them to string tracks, synthesizer pads and sound effects. Use the hall reverb's "wet/dry" control to change the degree to which the reverb affects the sound.
A reverb creates two types of sound: the early reflections, which appear at the beginning of the reverberated sound, and the tail or diffusion, which echoes at the end of the sound, then slowly dies away. The Korg M3's Early Reflection creates only early reflections, not a tail. Use this effect when you want to highlight a sound without pushing it into the background of the mix. The M3 provides a choice of four decay curve parameters for this effect.