The purpose of reverb (reverberation) is to make studio recordings sound as if they were done in live acoustic spaces, such as a recital hall, gymnasium, or tiled bathroom. In the glory days of analog recording, the “reverb” was often a cement-lined room in the basement of the recording studio, with a speaker at one end to fill the room with sound and a microphone at the other end to pick up the echoes. Today’s digital reverbs are quite a bit more convenient, and when adjusted carefully they can sound very good indeed.
Digital reverbs come in two basic flavors: standard and convolution. Convolution reverbs (Fig. 4) are typically more expensive and put more demands on your computer’s CPU because more mathematical computation is required. For many musical purposes, a standard reverb will work just as well.
When a sound is played in an actual room, it bounces off of the walls and other nearby surfaces. The first few bounces can sometimes be heard as separate echoes, especially if the room is large and the walls are concrete. These separate echoes are created in a digital reverb as “early reflections.” You’ll probably be able to control the level of the early reflections as a group. The later reflections blend together in a continuous wash of sound, which is called the decay or the tail.
Most digital reverbs let you set the decay time, which is the amount of time it takes the tail to die out. You may also be able to control the density or diffusion of the tail. A low density or diffusion setting will cause the reverb to sound rather artificial and metallic, which may be exactly what you want. Higher density and diffusion settings sound more natural. You may also find a “room size” parameter that’s separate from the diffusion (Fig. 5).
Sound travels at roughly one foot per millisecond. In an acoustic space, if your drums are 50 feet from the nearest wall, you won’t hear any reverb at all for 100 milliseconds (1/10 second). To simulate larger spaces, reverbs have a parameter called “predelay.” Increasing the predelay gives a more cavernous effect, and reducing it makes the simulated room seem smaller.
Fig. 5 The reverb included with Ableton Live 6 has some basic controls (Predelay, Size, Decay Time, Density, Diffusion, and Dry/Wet balance) and also a few that are less common. The Spin section adds animation to the early reflections, while the Chorus warms up the sound.
This has been a short-and-sweet overview of effects for recording novices. Keep an eye on future installments of Plugged In. I’ll be covering a few other types of effects in shorter articles.