Reverberation – or “reverb”, for short – is an effect that emulates the actual acoustic properties of a given space, either real or imagined.
I’d even venture a guess that many – if not all – of your favorite tracks would sound quite different if the reverb was removed from their mixes.
So with that in mind, we’re going to take a closer look at the specifics.
History of reverb
According to legend, the first intentional use of reverb as a sound production tool occurred hundreds of years ago, when various world religions discovered that large, majestic cathedrals made human choirs sound massive and um, godlike.
Some even argue that the exact place of this discovery was in the cathedral at Piazza San Marco in Venice, Italy.
That said, most high-ceilinged concert halls of this period exhibited similar characteristics, thus these venues enhanced the sound of the orchestral and chamber performances of their era.
While it’s hard to say exactly when reverb began life as an intentionally applied tool (even if it was essentially architectural in nature), it’s easy to understand why.
So when recording technology arose in the 20th century, the sound of reverb soon became an integral part of its vocabulary.
The following chronological list of reverb tools illustrates how the technology evolved into what we hear today.
The first reverb simulators weren’t really simulators at all.
They were actual acoustic spaces – sometimes located in the basement of a recording studio – with a microphone and speaker that could be moved around to change the texture of the ambience.
The engineer would send the sound to the loudspeaker, which would stimulate the chamber’s acoustic properties, which would then be sent back to the control room and folded into the mix.
Later, someone came up with the wild idea of attaching a speaker to a thin section of sheet metal, then recording the result, which actually sounded like reverb.
(This technique is quite similar in principle to shaking a piece of sheet metal to simulate thunder in high-school theatrical productions.)
The character of various metals and plate sizes determined the overall decay and spectral aspects of the reverb sound.
Industrious producers with lots of time on their hands might want to pop over to prosoundweb.com and read the instructions on how to build your own plate reverb from scratch.
A variation on the principles behind plate reverb was used to create the spring reverb – a metallic, bouncy, watery effect that can be found in vintage guitar amps.
The neat thing about spring reverbs is that they can’t accommodate percussive sounds with lots of transients, thus creating a resonant squeak with every impact – an exotic sound unto itself.
Once computers entered the studio, the game changed completely.
Early digital reverbs were either extremely expensive (like the Lexicon 224) or sounded like excrement.
Of course, as processor speeds improved and RAM became plentiful, the quality improved in step with Moore’s Law and after a few decades, quality digital reverb became the standard.
The most recent development in reverb technology is called “convolution.”
Logic’s Space Designer (pictured above) is one of the most popular implementations of this effect.
In plain English, convolution reverbs are capable of actually sampling the exact acoustic characteristics of a space, then applying those characteristics to an audio signal.
The end result here is an extremely convincing reverb effect that’s almost indistinguishable from real acoustics.
The hardcore principles can be found in this Wikipedia entry.
Essential reverb parameters
Reverb type (algorithm)
When setting up your own patches, the first step is to determine what type of reverb sound you want.
This parameter is most commonly referred to as “type” or “algorithm.”
The most common reverb types are:
- Hall. The sound of a large concert hall.
- Room. A smaller space, like a club, garage, or even a tiled shower stall.
- Plate. A simulation of a simulation? Yep.
- Gated. This algorithm is the secret sauce behind those huge ‘80s rock drums that are due to make a comeback any day now, as it creates a huge reverb that ends abruptly, rather than fading out.
- Reverse. This effect simulates the effect of applying reverb to a reversed audio signal, then inverting the results so the reverb occurs before the original sound, creating a dramatic “swell” that’s been used in countless remixes, as well as the movie, “Poltergeist.”
Of course there are also quite a few variations on the above types, some quite exotic.
For example, Reason’s RV-7000 effect also includes algorithms for Arena (pictured above), Spring, Multitap (an echo effect) and Small Space.
In selecting a reverb type, let your ears be the guide and choose the algorithm that best suits the sound your processing and the overall vibe of your mix.
This one’s fairly self-explanatory – decay time determines how long it will take for the reverb to fade to silence.
With this parameter (seen above in Ableton Live’s Reverb device), you can also create reverberant effects that couldn’t possibly exist in nature, like a small space that takes several minutes to decay.
Here’s an interesting parameter that’s essential for recreating the behavior of actual acoustic spaces.
Pre-delay adds a touch of delay before the reverberant effect engages.
If you were in an actual hall and you clapped your hands, it would take a few milliseconds before the sound of your handclap reached the surfaces of the space, then a few more milliseconds before the reverb traveled back to your ears.
This parameter (pictured above in Live’s Reverb) allows you to fine-tune that time.
When applying it to drum sounds, it’s extremely important to have it set to either extremely short amounts or longer delay times that are perfectly in time with your tempo, for more rhythmic effects.
It can also be useful to add longer amounts of pre-delay when using a bit of reverb on a vocal.
This way, the reverb doesn’t kick in until after the voice has stopped, giving each element a tad more room to breathe.
This is one of the subtlest parameters in a reverb device, but here’s an easy shortcut to understanding it.
Diffusion equals “smoothness.”
In a real acoustic space, lots of different surfaces (soft, hard, various angles, human bodies, etc.) will add complexity to the reverb tail, thus making it more of a wash.
The diffusion knob (seen above in Reason’s RV-7000) increases that complexity, resulting in a velvety texture as the reverb decays.
Sometimes this component is an algorithm in itself, other times it’s a knob or section of knobs (as seen in Live’s Reverb, pictured below).
When the reverberant signal first returns to the listener, some of the earliest acoustic reflections arrive at the ear discretely before the whole acoustic space is excited into reverberation.
These are aptly named, “early reflections,” and sound a like a quick series of jittery short echoes, which is exactly what they are.
Smaller spaces have more pronounced early reflections, and this parameter can be put to great use when applied unconventionally – so experiment with it to see if it fits your sound.
It’s kinda cool when applied judiciously in minimal techy tracks.
If an acoustic space has lots of soft absorbing materials, like curtains, couches, and a mass of water-based human bodies, then the high frequencies tend to decay faster than the lower frequencies.
On the other hand, if the space has lots of hard surfaces like metal and mirrors, those high frequencies will bounce around, ringing sharply.
The damping parameter – sometimes called “HF damping” or “high-frequency damping” – determines how quickly the treble frequencies decay.
Some reverbs also include a “LF damping” parameter as well, which affects the lower frequencies.
The general rule of thumb here is that if the parameter is simply called “damping,” it’s HF damping.
That said, some manufacturers refer to these parameters using different terminology, such the Ableton Live reverb’s “diffusion network,” (pictured above) which does essentially the same thing.
Using reverb with other effects
Flanger or Phaser. Adding a touch of phaser or flanger to the reverb’s fully wet signal can create unusual sweeping effects that range from subtle animation to full-on whooshes.
Auto-pan or Tremolo. Tempo-synced tremolo adds a bit of bounce to the reverb tail, which sounds fantastic in a track that pumps.
Sidechained dynamic effects. If you want to key the above reverb bounce to the rhythm of another instrument, try using a compressor or gate sidechain effect instead of auto-pan.
Equalization. While it’s obvious that adding an EQ will give you a lot of control over the spectral character of the reverb, you can also create some really unusual drones by using very long decays and extreme EQ settings over very narrow frequency ranges.
Until next time…