Reverb is an incredibly useful effect for simulating various acoustical environments, adding sonic variation, and tension to electronic dance music productions. Reverberation (reverb, for short) can be defined as the effect that an environment has on certain characteristics of a sound. When a note is played on a piano in small a church, for example, the majority of what we are hearing is direct sound which travels from the piano to our ears. However, depending on where we are sitting in relation to the piano, in addition to the psychoacoustic properties of the church, we would also hear indirect sound, as it bounces of the walls and ceiling of the church interior before it reaches our ears. These reflected sounds result in the creation of a series of echoes, which can heavily alter the perceived characteristics of the direct sound.
Different types of reverberations are quite telling in terms of the environment in which sounds originate, as we can make accurate assumptions based on the length of time between the origination of a sound and the decay, echo, diffusion, and density of secondary sound reflections. These assumptions about the psychoacoustic properties of a sound are prewired in all of us, and as such make for a great means of manipulating perceived spaces by processing certain sounds with a reverb unit which mimics different acoustic environments. Though it is not possible to perfectly recreate various acoustical environments, high-quality reverb units are capable of coming close enough to where effect is sufficient to mimic these environments with a degree of accuracy sufficient to achieve the desired effect. When producing electronic dance music, reverb allows our synthesized sounds and atmospheres to achieve a degree of realism by emulating spaces which occur in real-world recording settings, without the need for fancy miking techniques or tedious and costly on-location recording. Electronic dance music also benefits from automated reverb modulation, in that a producer is able to build tension as perceived spaces build and fade in a mix, creating tension and release necessary to engaging the listener.
Convolution Reverb vs. Algorithmic Reverb
The sonic properties offered by the many available reverb units on the market today vary greatly depending on the type of reverb and the quality of the unit. Convolution and algorithmic reverb units are the two most popular methods used in available reverb units, with each having its own benefits and setbacks in relation to the other.
Convolution reverbs use impulse responses to achieve their effect. Impulse responses are real sound samples, recorded from real rooms (or from real hardware reverb units) which achieve accurate results similar to real-life environments and popular hardware. While the actual process of convolution is quite complicated, it is sufficient to understand that convolution reverb plugins can be of incredibly high-quality, with the only major drawback being the hit on a computers CPU necessary to achieve the desired effect.
Algorithmic reverb units use mathematical algorithms to recreate the decay, echo, diffusion and density of real-life environments with very little hit on a computers CPU. These are the most popular units in that they are relatively effective and cheaper to manufacture. Algorithmic reverbs are often included with many popular DAWs and vary in their ability to mimic real-world impulse responses. Though some high-end algorithmic reverb units do exist, it is generally accepted that convolution reverbs are of higher quality and preferable in most production settings.
Reverb Control Parameters
Both convolution and algorithmic reverb units offer similar controls over the characteristics of the sound they produce. The most commonly featured parameters on modern reverb units are wet/dry (mix), pre-delay time, reflections (early/late), diffusion, density, decay time and damping.
The mix parameter is the simplest of controls found on most reverb units, and is used to adjust the amount of reverb applied to a sound. When using a reverb unit directly on an instrument channel the reverb amount can be adjusted using the mix control. Usually it is preferable to send the instrument to an auxiliary bus with the reverb unit present. In this situation it is best to keep the mix all the way up to 100 percent. Sending reverb to an auxiliary bus allows the reverb to be panned away from the instrument, which helps free up space in the center of the mix.
Pre-delay controls the time separation between the direct sound and the reflected sound. Longer pre-delay settings will lengthen the perceived distance between the listener and the sound source. The most practical use of pre-delay is to simply adjust it so that the initial transient of the instrument is not swallowed by the reverb effect. Moderate to low pre-delay settings are all that we need in order to achieve this effect. Without enough pre-delay our instruments will be drowned in reverb and lost in the mix.
Though once only found on high-end units, early reflection parameters are now more commonly found on reverb plugins and allow for precise control of the early, first-order reflections created by a sound. Since most natural sound reflections are complex and involve many different surfaces and reflection times, early reflection controls allow for a heightened degree of realism if used correctly.
In addition to controlling the amount of early reflections heard, diffusion parameters allow for controlling the spread of those early reflections across the stereo image. Diffusion levels will directly affect the depth of a sound and can be used to create great amounts of tension in a mix if used properly. Automating this parameter can also lead to some incredibly thrilling transitions in electronic dance music productions if done with care.
In large spaces, reflections take longer to decay into silence than in a smaller ones. The decay parameter will control this aspect of our reverb effect. As a general rule, it is best to set decay times on instruments based on the nature of the instruments timbre itself. For example drums benefit from shorter decay times, whilst strings and pads benefit from longer ones. As long as decay settings are such that the reverb tail fades before the next note, most instruments can benefit at least small amounts of reverb. In certain situations, a gate can be applied to the reverb channel in order to assure that the decay of one note does not bleed into the next one. Using a high threshold on the gate, as soon as a note finishes, the gate will prevent the reverb tail from washing over the following transients. Though gates on reverbs do not lend themselves to a very organic sound, such effects can be used creatively to liven up a mix.
Damping parameters allow for the reduction the high-frequency and/or low-frequency content in reverb tails, which can create the impression that the sound source is occurring in an area with less reflective surfaces (imagine the reflections of sound off of empty church walls and ceilings versus a small carpeted room crowded with furniture). Often times damping is applied to the lower frequencies in order to eliminate muddiness and rumble caused by sound reflections. Applying EQ to a reverb effect can achieve similar results, and depending on the desired effect, can keep the undesirable effects of reverb under control.
Reverb has many uses in electronic dance music production, from livening drum-loops, to enhancing kick transients, to creating dramatic build-ups and washes. Whether you are working with convolution or algorithmic reverb units, it is best to become familiar with the basic controls mentioned above so that reverb can be tailored to suit your production needs. In the future we will discuss some more advanced production techniques utilizing reverb, though these are best left for those producers who are familiar with the more basic functioning and theory behind reverberation and its many applications.