What Reverb?

d16 Torraverb 2Getting to know the different types of reverbs and how to use them in your productions is an essential part of creating good mixes. Most of us will have a few different reverb types that come with your chosen DAW, 3rd party plugins, or hardware of choice. You’ve almost certainly seen terms such as “Plate”, “Hall”, “Spring”, “Room” & “Convolution” & “Algorithmic” in forums or magazines. This post will attempt to help explain the basic differences between reverb types and hopefully help you choose the right reverb for the job in hand.

HALL REVERB

The hall reverb is one of the most commonly used types of reverb. As the name suggests they are designed to emulate the reverberation effect of large halls, or other large spaces such as theatres or even churches. Real life reverberation in a concert hall is characterized by a long reverberation, and hall reverb setting that emulates that environment will do the same.

Since these types of reverbs are great for modelling large natural physical spaces, it’s no wonder that they are a common go-to reverb. However, it’s important not to get carried away when using them. If you apply too much of a hall reverb in a mix the long reverberations can make your mix sound too distant or drowned out, or just plain muddy.

It’s worth noting that many algorithmic reverbs that emulate hall reverbs now have parameters which can be configured to produce effects that are completely “unnatural” and help you avoid that pitfall. For example, with modern digital processors you can have the depth and spaciousness of a large hall, but without having the long tail muddying up your mix. Many high-end digital reverbs also use modulation which can add richness to the signal.

Hall reverbs are rich, warm and big. They are generally a good choice for adding some three-dimensional ambience to your mix. Because they are big, they are often used to fill out the back end of your mix – adding some depth without overpowering the front of your mix.

ROOM REVERB

A room reverb is similar to hall reverb, normally designed to emulate the reverberation of something being recorded in a room. Because they are emulating smaller spaces than halls, this results in the reverberations being much faster with faster decays. (Think of clapping your hands in a small room versus a church and how that would sound). For this reason, things like drums and guitars are good candidates for room reverbs.

Room reverb is a great choice to add some realism to instruments that are recorded by a microphone in very close proximity to the instrument and are also very good for adding some character to an instrument that is recorded directly into our sound card or DAW. A decent room reverb will give the listener a sense that the instrument is being played in a real room.

As with the case of Hall reverbs, misuse of the room reverb can also have detrimental effects. Too much room reverb in your mix can overemphasise the “smallness” of the environment, making it sound boxy or small. Also, too much of a poor room reverb will often add resonances that don’t work well with your mix. Even a more sophisticated room reverb can make the recording sound distant from the instrument if overused.

A common parameter in reverb units that you shouldn’t overlook is is Pre-delay Time. Good use of this will allow you to add sufficient room reverb to your instruments but still keep them sounding “present” in the mix. Pre-delay allows you to specify the amount of time between the start of the direct sound and the start of the first sonic reflection.

By increasing the Pre-Delay, you can create a small gap between the initial onset of your sound and the beginning of the reverberations – what you are looking for is a nice blend between the two that makes your instrument sound “close” but also gives the listener a sense of the “room” it’s in.

PLATE REVERB

Plate reverbs emulate very early methods of generating a reverb.

‘During the ’60s and ’70s, most artificial reverb used on recordings was generated using a reverb plate, sometimes called (inaccurately) an echo plate. The reverb plate is an ingeniously simple device, but it takes a lot of tweaking at the design stage to get it sounding right. Plates work by suspending a thin sheet of metal under tension within a rigid frame via springs or clamps attached to the corners.

A transducer similar to the voice-coil of a cone loudspeaker is used to inject audio energy into the plate and two or more contact mics fixed to the surface of the plate then pick up the vibrations inside it and feed them to preamps connected to the console effect returns. By feeding the different contact mics to the left and right channels, a pseudo-stereo reverb output is created.

Plates have a similar sound to hall reverbs that is usually denser and flatter and more two-dimensional sounding. They are clean and bright sounding and are great at adding some overall length and size to a sound without it making it sound distant or small. As a result, they often sound amazing on vocals or snare drums – and because they are different to hall reverbs and don’t add the same feel of distance or depth they can often blend better with the original sound.

As a result of their unique characteristics, plate reverbs are making a bit of a come-back now that more accurate digital emulations are now available to the “in the box” producer.

SPRING REVERB

Historically, spring reverbs have been adopted by those who could not afford the more expensive plate reverbs or simply didn’t have the space for a plate reverb in their studio. They are also still commonly found in guitar amplifiers.

The mechanics of a spring reverb are similar to a plate reverb in that a sound is injected into it and the coil of the spring then reverberates and those reverberations are then recorded. However, because of the physical characteristics of springs vs. plates, spring reverbs can also add a characteristic ringing sound and can also feedback into themselves.

Generally speaking, spring reverbs are usually used on individual instruments to add their unique characteristic sound, rather than on a whole mix or set of sounds. For example, if you use it on a guitar it can add a twangy bounce to it. Used on other instruments such as electric piano or an organ it can add a vintage warmth and dimension to the sound.

Due to the twangy nature of spring reverbs, you probably wouldn’t usually use one on vocals or drums, but they can add a weird psychedelic effect if that is what you are after. Like other reverbs, adding too much spring reverb in a mix will make it sound distant and often lo-fi.

ALGORITHMIC REVERB

With the advent of computers able to perform intricate and multiple calculations very quickly, variations of the traditional reverb effects are now possible. Digital reverbs (also called algorithmic reverbs) use various signal processing algorithms in order to create a reverb effect.

As these include calculated processing by a computer, they often include many additional parameters that aren’t included in a traditional reverb effect. These additional parameters can make them very versatile, especially if you are wanting to emulate a traditional natural sounding reverb, but with a few extra “unnatural” bells and whistles.

For example, most high-end algorithmic reverbs also have modulation – meaning the internal parameters of the reverb subtly move and change over time. This can produce a rich and organic effect. Furthermore, many include LFOs and envelope followers. The LFOs will change the parameters of the reverb constantly over time, and the envelope followers allow the reverb parameters to dynamically respond to the level of the audio signal.

When these are used subtly, it can inject life and motion to the reverb sound. If they are used at extremely high settings it can create strange effects and the characteristics of a reverb to jump around dramatically.

CONVOLUTION REVERB

A convolution reverb is a kind of reverb that uses samples, (which are often called impulses) of real-life acoustic spaces. The process in itself is a pretty heavy mathematical equation which it is why they have only become available in the recent years. Convolution reverbs can produce a very realistic snapshot of a particular acoustic space and as such are often great for post-production in things like film effects.

Unlike many of their algorithmic reverb counterparts, convolution reverbs may have a more limited ability to modify the various reverb parameters that are included in a standard algorithmic reverb.

However, in most cases convolution reverbs will include options to use impulses that are not modelled after natural spaces to produce reverbs that don’t necessarily sound like any natural acoustic space. As an example, if you are into experimental sound design you can try feeding all sorts of impulses into your reverb to see what you end up with. The beauty of a convolution reverb is that it allows you to experiment with just about any impulse and see what it produces.

So that sums up our little look at various types of reverbs and their characteristics. I hope you’ve got a better sense of the basics – and of course, we’ve really only scratched the surface. I will leave you with a couple of common reverb effects worth trying out in your own production, no matter what reverb you end up choosing.

REVERSE REVERB

Reverse reverb is also sometimes referred to inverse reverb and is exactly what the names suggests – a reverb that runs backwards. So instead of the reverb starting with the sound and gradually decaying, it starts quietly and gets louder until the original sound is heard. Before the days of digital reverbs this effect was created by recording a reverb whilst the tape ran backwards, then playing the tape forwards again.

Of course, these days if you are working in a DAW all you need to do is record a reverb from a sound, reverse it and play it back.

This is an unnatural effect but works very well with introducing vocals or leads and can also create unusual ambient parts.

GATED REVERB

The gated reverb effect became very popular in the 80’s and 90’s and was heavily used by artists such as Phil Collins and Michael Jackson. The way these were usually set up was by inserting a gate after the reverb and triggering the gate with the pre-reverb sound. The gate time would be adjusted so that the initial bursts of reverb come through, but the tail end of the reverb is cut dead.

The effect was often used to add power and body to snare drums and other percussive instruments.

Many modern reverb processors will emulate a gated reverb by using an algorithm that creates a variation of the traditional gated reverb effect. In this case, instead of the reflections of the reverb gradually building up in time before they are gated, they will stay at a constant level.

On a sparse, short instrument with no overlapping parts (such as a regular snare beat), this emulation sounds very close to a gated reverb. However, on sustained melodies like vocals, the effect is different. The result can be that it sounds more like the reverb is following the melody line. Generally, this effect can be useful if you want a large or wet reverb sound that doesn’t decay for very long.

Of course, if you are after the traditional gated effect, you can simply insert a gate on your reverb and set it up as previously mentioned, and this will yield slightly different results.

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