PLEASE NOTE: This article has been archived. It first appeared on ProRec.com in November 2009, contributed by then Editor Kim Lajoie. We will not be making any updates to the article. Please visit the home page for our latest content. Thank you!
So you’ve got a handful of reverb plug-ins, or a hardware reverb processor with various types of reverb. Maybe you’ve seen terms like “Hall”, “Plate”, “Inverse”, and “Convolution” being discussed in magazine articles or on forums. Maybe you’ve got a vague idea about it all, but you’re still wondering what it actually means and how to apply them in a mix. Well, read on.
This is the most common type of reverb. As the name suggests, hall reverbs are usually designed to simulate the kind of reverberation effect produced by large halls.
A hall reverb is usually a good choice for adding a three-dimensional ambience to your mix. Good hall reverbs tend to fill out the back of the mix, adding depth without crowding the foreground.
Many algorithmic reverbs that simulate halls have many parameters, and sometimes can be configured to produce sounds that don’t sound like any real-life physical space. A useful “unreal” configuration is to use a large hall size in conjunction with a relatively short reverb time. Real-life large halls almost always have a long reverberation time. However, with digital processors you can have the depth and spaciousness of a large hall, but without having the long tail muddying up the mix.
Many high-end digital reverbs also have some kind of modulation, where some components of the internal reverb model are in motion. Again, almost no real-life hall has its size and shape constantly adjusting during a performance. The digital processor, however, can use modulation to add a richness and organic quality that works well with music.
Too much hall reverb in a mix can sometimes make the mix sound distant, or all washed out. Using a long hall reverb in a dense mix or fast song will often turn the mix into a mess without creating a good sense of ambience. Using a short hall reverb in a sparse mix or a slow song will diffuse and blur the sound without adding spaciousness and depth.
In this audio example, IK Multimedia CSR Hall is used to generate an evocative, dark, deep hall. This is the kind of reverb you’d use to add colour and space to a mix.
Djembe: The djembe brings out the fluffiness and softness of the reverb sound. This would be especially useful in a hybrid style where the reverb blends with a soft synth pad or choir.
Piano: For the piano, the hall makes the sound larger and wider, but without an obvious change in the character of the sound. The piano can “take” more reverb before the sound changes significantly because the decay of the piano chords blend with the decay of the reverb.
Guitar: The guitar combines the effect of djembe and piano. The reverb adds size and depth while the chords are sounding, but it’s still noticeable in the gaps between the chords. This reverb mix is quite strong, making it more suitable for a background rhythm guitar.
Vocals: The reverb responds quite heavily to the deep male vocal, resulting in a thick, rich sound. Using less reverb in a mix would add that same thick richness in a more subtle way. The female vocal is given a spaciousness and depth that will sound just right in a full mix.
Room reverbs are similar to hall reverbs in that they are usually designed to simulate the natural sound of an acoustic space. Unlike halls, rooms are smaller spaces, which usually means they’re much faster than halls with less bloom and a quicker decay.
A room reverb is good for adding realism to instruments that have been recorded with very close mic positioning or direct injection. Guitars and drums are likely candidates for room reverbs. A good room reverb will give you the sense that the instrument is being played in a real acoustic space.
Room reverbs can also be useful as an alternative to a slap or echo delay. Start by making the reverb time quite short and using a relatively long pre-delay time (or by inserting a delay on the reverb bus). Using a room reverb instead of a straight delay adds some diffusion to the delayed sound, which helps it sit behind the original sound. It can also help make a slap or echo delay sound more “real”, especially if the mix mainly contains acoustic instruments.
Too much room reverb in a mix can sometimes make it sound boxy or small. Too much of a poor (not very sophisticated) room reverb will add ugly resonances that don’t work well with the music. Too much of a more sophisticated room reverb will make the recording sound like the microphones were too far away from the instruments.
In this audio example, IK Multimedia CSR Room is used to generate the ambience of a dry room. This is the kind of reverb you’d use to add some subtle air and ambience to a mix.
Djembe: The percussive nature of the djembe really “catches” the room. The ambience added to the sound adds some air and space so that it doesn’t sound so dead or choked. This would be useful in a mix featuring a lot of acoustic instruments, where you’d want to put all the instruments in a believable acoustic space.
Piano: Like the hall, the room makes the piano larger and wider. The difference is that the room reverb doesn’t make the sound linger, making the chords sound less blurred (which may or may not be a good thing, depending on the mix). The tail also has more of a smaller acoustic sound, compared to the hall’s dreamy spaciousness.
Guitar: Notice how the room reverb adds a sense of realism to the guitar. Where the dry guitar sounds like it’s in a vacuum, the room reverb gives a real sense of being there in a room with an amp in it. It adds air and space around the sound without sounding unnatural or overpowering.
Vocals: Like the hall, the room adds thickness and richness to the male vocal. Unlike the hall though, it adds dimension and size without a tail that might clutter the mix. Likewise, the female vocal gains just a little air from the room reverb. This would be useful if you want to add some natural wetness to the vocal without taking up too much additional space in the mix.
Plate reverbs simulate an earlier method for generating reverb, by injecting sound into a large hanging sheet of metal and letting it reverberate. Plate reverbs have a similar shape to hall reverbs, except the sound is usually denser and flatter (two dimensional).
Plate reverb is great for adding length and size to a sound without making it sound distant or small. Plate reverbs are often the “secret sauce” that can help make a vocal or snare sound amazing. Because they don’t add depth or distance like a hall reverb, plate reverbs can blend better with the original sound. As the plate reverb becomes a part of the sound, you can sometimes add a little more than you might otherwise be able to with a hall reverb. This is a great way to get a really lush vocal sound without making the whole mix sound drenched. It’s also a great way to add a bit of power to a snare drum that’s too short or weak.
Too much plate reverb will make the mix sound flat and two-dimensional, lacking ambience or depth.
In this audio example, IK Multimedia CSR Plate is used to generate a typical plate reverb. This sound is a good general starting point, from which you could adjust to suit your mix.
Djembe: At first, the plate might sound a little like a hall or room reverb. In the mix, however, a plate reverb doesn’t provide any of the usual cues of depth or dimension. Instead, you’ll find that it adds some “sheen” without interfering too much with the rest of the mix.
Piano: Here you can hear the unnatural sound of the plate. The piano sounds more lush, but it doesn’t sound like anything’s been added to it. This is plate reverb at its best.
Guitar: As with the piano, the plate reverb seems to become part of the guitar sound, making the guitar more lush without adding clutter to the mix.
Vocals: The plate adds an audible tail to the male vocal, but the tail doesn’t have the depth of a hall reverb. While it’s noticeable on its own, this tail will disappear into a mix much easier than the tail of a hall reverb. Notice the female vocal has some added width and length from the plate, but the sense of space or dimension doesn’t change.
Spring reverbs simulate a method of generating reverb that is commonly built into guitar amplifiers, by injecting sound into metal springs and letting them reverberate. Spring reverbs tend to sound bouncy and lo-fi. They can also be “ringy” and feedback into themselves.
Spring reverbs are typically used on individual instruments rather than full mixes. Used on guitars, they can add a twangy bounce and liveliness. For instruments such as electric pianos and organs, spring reverbs can add a vintage depth and dimension to the sound. They’re usually not used with drums or vocals because the sound is not as smooth as other reverbs. On the other hand, you might want to try it out for a strange or psychedelic effect!
Too much spring reverb in a mix will make it sound lo-fi or distant… but that might be exactly what you’re looking for!
In this audio example, the sound files are processed using a real physical spring reverb (not an emulation). This is a spring reverb that is commonly used with guitar amplifiers. This particular spring reverb is mono.
Djembe: Notice how the percussive nature of the djembe excites the springs. You can hear a wet kind of “boing” sound. The spring reverb adds a kind of ambience that sounds genuine but charmingly inaccurate.
Piano: The spring reverb adds a genuine vintage dimension to the piano. Again, it doesn’t sound like any acoustic space we might know, but the physical vibration of the springs brings a kind of reality to the sound that is unlike any digital reverberation.
Guitar: This is the natural home of a spring reverb. The reverb simply becomes an integral part of the sound, adding a particular character to the sound of the guitar.
Vocals: The spring reverb adds a distinctive character to the sound of the vocals. This is not a sound that’s commonly used, but might be interesting for a lo-fi effect.
Reverse (sometimes referred to as “inverse”) reverb is the sound of the reverb running backwards. So instead of starting with the original sound and gradually dying away, it starts quietly and gradually gets louder until the original sound is heard.
Before digital reverbs, this effect was created by recording the reverb (usually an actual plate or echo chamber) while the tape runs in reverse. When the tape is played forwards again, the reverb is heard in reverse. The result is a reverb that is heard before the original sound (instead of directly after). These are not based on any sound in reality and are sometimes useful for special effects or unnatural ambiences.
Reverse reverbs are most commonly used for “devil” or “possessed” voices, but are sometimes useful for more subtly adding an unusual ambience to a part.
In this audio example, IK Multimedia CSR Inverse is used to generate the sound of a reverse reverb.
Djembe: The inverse reverb adds a spooky or ghostly ambience to the djembe. Note that the reverb is long enough to fill in the gaps between the djembe hits, so there’s no dead space. If the reverb were shorter, the dead space would occur directly after the hits (instead of directly before, as with normal reverbs).
Piano: The piano’s attack is softened by the inverse reverb, and it begins to pick up just as the natural decay of the piano notes are fading away. In a mix, this would turn the piano part into more of a “wash” that contributes more tone to the mix and less rhythm.
Guitar: Here you can hear the inverse reverb as a kind of twisted ambience. This might be useful for a breakdown section in a song, as an interesting effect.
Vocals: Here the inverse reverb adds that familiar reverse sound. The male vocal is spoken and more articulated, producing that “devil voice” effect. The female vocal shows the other common use of reverse reverb, to bring in the vocals at the start of a verse.
Gated reverb was popular in the ‘80s, especially on snare drums. These were traditionally set up by inserting a gate after the reverb, but triggering the gate with the pre-reverb sound. By adjusting the gate time, the initial burst of the reverb comes through, but the tail is cut off. This was used to add power and body to snare drums without having the reverb tail muddy the mix.
Many modern reverb processors simulate a gated reverb by actually using an algorithm similar to an “inverse” (or non-linear) algorithm. Instead of reflections gradually building up in time, they stay at a constant level. On a sparse short instrument with no overlapping parts (such as a regular snare beat), this simulation sounds close enough to a gated reverb. However, on sustained melodies (such as vocals), the effect is different. It sounds more like the reverb is “following” the melody line. This can be useful if you want a large or wet reverb sound that doesn’t linger on for very long.
These days, gated reverbs are still good on snare, but you might want to keep it subtle unless you’re mixing a power ballad!
In this audio example, IK Multimedia CSR Inverse is used to generate a gated reverb. Because this is generated by an inverse algorithm, it is not a “true” gated reverb.
Djembe: The djembe reveals the nature of the gated reverb. You can hear the start of a reverb tail that implies a very large space, but the tail itself stops suddenly and doesn’t decay naturally.
Piano: Here you can hear the spread produced by the gated reverb. This is especially pronounced on the attack of the sound. Notice, though, that the chord changes are very clean. The previous chord does not linger on like a regular hall might (if it were as bright and as large as this gated reverb).
Guitar: Notice how the gated reverb adds a very large and spacious sound to the guitar without cluttering the mix with a tail that decays naturally. In this example, the tail is cut before the chord changes, so each chord has a clean, fresh attack.
Vocals: The gated reverb on the male voice sounds like a special effect because the voice is spoken, not sung. The female vocal benefits from the spacious tail that seems to follow the melody almost like a delay would.
Algorithmic reverbs are a kind of reverb that is calculated in real-time. Most famous digital reverbs by companies such as Lexicon, TC Electronic, and Eventide, are algorithmic reverbs. These usually have many parameters, making them very flexible and versatile.
High-end algorithmic reverbs also have modulation. This is where the internal parameters of the reverb subtly shift and change over time, producing a more pleasant and organic sound. Some high-end reverbs also have LFOs and envelope followers. LFOs allow the parameters of the reverb to constantly change over time, and envelope followers allow the reverb parameters to dynamically respond to the level of the audio. Used subtly, these can add life and motion to the reverb sound. Used in extremes, they can produce some strange effects where the reverb characteristics jump around dramatically.
Algorithmic reverbs often offer the most musically useful sounds, and can often be tailored to the specific mix you’re working on.
The next two audio examples demonstrate some of the stranger effects possible with algorithmic reverbs.
In this audio example, IK Multimedia CSR Room is configured with heavy reverb tail modulation, and the two LFOs are used to modulate several parameters. LFO1 is quite fast and modulates decay level, input level, and low frequency gain. LFO 2 is slower and modulates high frequency decay and stereo width.
In this audio example, IK Multimedia CSR Room is configured with an envelope follower controlling reverb decay time and hi frequency decay. This is used to create a reverb that is long and dark when the audio is loud, but short and bright at the end of the notes. Fast tail modulation and stereo image modulation add an unnatural fluttering effect.
Convolution reverbs are a kind of reverb that uses samples (often called “impulses”) of real-life acoustic spaces. The convolution process itself is particularly math-heavy, which is why it’s only become feasible in recent years. These reverbs can produce a very realistic “snapshot” of a particular acoustic space, but often have limited ability to modify the reverb sound to suit the music. On the other hand, convolution reverbs can use samples that have been synthetically generated, producing reverb-like sounds that don’t sound anything like an acoustic space! Convolution can also be used for sampling the tonal response of other equipment like guitar cabinets or other speakers.
Convolution is useful for work like film sound effects, where it’s important to create a convincing illusion of an acoustic space. It’s also sometimes useful for creating natural, realistic spaces when mixing acoustic instruments. It might also be worth looking at convolution if you’re into experimental sound design and you want to try feeding it all sorts of sounds that were never meant to be reverbs! Interesting (and almost usable!) results can be had by using drum samples as reverb impulses!
The next two audio examples demonstrate some of the stranger effects possible with convolution reverbs:
In this audio example, a convolution reverb is loaded with a buzzy tonal sample. You can hear how that tone is reinforced in the audio being processed, even turning the djembe from a non-pitched instrument to a pitched one!
In this audio example, a convolution reverb is loaded with the sound of a crash cymbal. You can hear how it now sounds like all the instruments are being played “through” the cymbal, or “morphed” with the cymbal.
Reverb is a subtle and complex tool, perhaps even more so than compression! It’s sometimes quite difficult to hear the differences between different types of reverb. It’s also often hard to know ahead of time which reverb type to use in a mix because the effect isn’t really felt until it’s set up across the whole mix. Even then, it’s usually something that sits in the background and doesn’t draw attention to itself. Listening to reverb is an exercise in listening to the background – not even the sounds in the background, but how those sounds interact with an ambient space. It’s listening to the space between the sounds. Don’t despair though – with a good understanding of reverb and a bit of practice, you’ll be on your way to becoming a reverb master!