As one of the key tools in any mix, reverb is fundamental to the sound of your tracks. Bruce Aisher walks us through the options available for adding ambience to productions.
As one of the oldest, most basic effects used in music production, reverb plays a vital role in shaping the sound of a mix, helping to glue different elements together, providing a sense of space and contributing to a feeling of three-dimensional sound. With so many options on offer, the sound of a reverb effect can be anything from the most subtle room ambience to a huge, cavernous echo. As a result, selecting the right tool for the job is essential. Before we start choosing types of reverb to apply to particular sounds, we need to understand the various options on offer and how they differ from each other. Reverb effects can usually be broken down into two main categories: those which recreate the sound of real ambient spaces and those which recreate the sound of other artificial echo-style effects. Let’s take a look at how these two strands developed.
Early reverb effects
The first form of reverb used in recording was achieved simply by playing a sound through a loudspeaker in an echo chamber – a reverberant acoustic space – and recording the resulting sound back into the mix. One of the more successful early attempts at creating artificial reverb came in the form of the plate reverb – a large, loosely suspended sheet of metal with a loudspeaker bolted onto the centre. The speaker would be fed an audio signal and cause the plate to vibrate, whereupon pickups around its edge would send a reverb-like signal back to the mixing desk.
Check out this clip of the UA EMT 140 plate reverb plugin in action. Note the density of sound and how it builds up and decays:
A cheaper, more portable, version of similar technology became popular in guitar amps in the form of spring reverbs. These simply used a metal spring rather than a plate. The sound is generally distinctly lo-fi, great for adding character but not appropriate when subtle, realistic reverb is required.
The modern age
The problem with real plates, springs and echo chambers was that their sound could only tweaked in quite subtle ways; it was very difficult to completely change their sonic characteristics. This all changed with the advent of commercially viable digital reverb in the late 70s.
Lexicon, one of the companies at the forefront of this revolution, used digital signal processing technology to create emulations of different reverberant spaces. Various parameters could be tweaked, as well as the basic algorithm on which each space was built: room, hall, etc.
The UA Lexicon 224 plugin simulates the look and feel of one of the company’s early classics:
Algorithms were built using multiple interacting delay lines to reproduce a room’s ‘early reflections’ followed by the reverberant tail.
As technology developed, sophisticated algorithmic reverb hardware eventually enabled the user to tweak a huge range of parameters in order to tailor the sound to their specific requirements. Unsurprisingly, from the earliest days of the DAW, manufacturers sought ways to distil existing hardware reverb technology into the new computer-based format. This in time led to the reverb plugins we know today.
Algorithm-based reverb plugins such as Cubase’s RoomWorks offer a variety of different flavours of reverb which aim to cover every type of sound the producer might want:
It’s interesting to note that reverb designers still tend to include plate algorithms in their all-digital designs, as the familiar density and decay of plate effects has became a sought-after sound in its own right. A plate echo algorithm is still a great choice for a classic reverb sound.