Reverb adds space around your notes and can make your sound seem farther away, even dreamy. It’s short for reverberation, which describes the continuation of sound in a particular space after the original sound is produced and stops or decays away. Reverb produces a kind of hazy or blurred type of echo that’s very pleasing to the ear and gives a sense of the space you’re playing in.
The character of a reverb is defined by several factors, including the following:
The overall size of the space you produce the sound in
The number of surfaces the sound can bounce off of (how enclosed is the room, how high is the ceiling, and so on)
The material of the walls (wood, concrete, glass, or whatever), which affects how much sound they absorb and how distinct the repetitions/reflections are
Put simply, various types of reverbs can make it sound like you’re playing in all kinds of different spaces.
Keyboards typically give you a limited set of parameters you can use to adjust reverb. The most common are:
Mix or wet/dry mix: Mix controls how much of your original, unaffected (dry) signal is passed on and how much of the reverberated (wet) signal is introduced. Often, just a little wet signal is good enough to produce a nice, not-too-sloppy sound. But sometimes a lot more of the wet signal is nice, giving your playing a spacious quality and majestic sound.
The more notes you play or the faster the tempo, the less reverb you want to use. This way, all your playing can be clearly heard without blurring together.
Type: Type is an overall selection that sets the size of the space and other associated parameters, or even the method of producing the reflections. Common choices are room, hall, stage, cathedral, and so on.
You may sometimes see plate or spring, which is a form of artificial reflection where a sound is played into a box that contains a metal plate or large spring, which vibrates from the incoming sound waves.
Size: The size control defines the overall size of your chosen simulated space. So a small room may seem like a tiny hallway or closet, and a large room may be 10 feet by 20 feet or 40 feet by 40 feet.
The idea of a small cathedral or canyon may seem funny, but remember that the type of room is defined not only by its floor space but also by characteristics like ceiling height and the materials the walls are made of.
Reverb time: This control simulates how long the sound reflections take to die away or stop sounding. It’s casually described as a length — a short reverb, a long reverb — and the reflections are sometimes called the reverb tail.
On many simple keyboards and digital pianos, mix and type may be your only control choices. More advanced reverbs that offer deeper programmability include parameters such as:
EQ: Shapes the tone of the sound a bit.
Damping: Simulates how much of the sound is absorbed; higher values cause the reflections to come back darker or less bright.
Pre-delay: Pushes back the whole reflective simulation, so your original dry sound can be heard before the reflections start. Adding some pre-delay (or raising its existing value) helps your sound be clearer and more distinct before being wrapped in the ambience of the effect.