There are two ways of creating a reverb effect in the digital world, by using mathematical calculations to create a sense of space, which is called Algorithmic. And by creating an impulse response, a snapshot of a real space, and applying that to the sound, which is called Convolution.
Reverb is essentially a series of delayed signals, and Algorithmic reverbs work pretty well to recreate this. Most reverb plugins, stomp boxes, and racks are algorithmic style.
Analog Reverb Types
In the analog world there are a few other ways, most of which will not be available to the home studio musician, except for their recreations in plugins.
Analog reverbs come in 3 flavors, Plate, Spring, and Chamber.
Invented in 1957 by EMT of Germany, the plate reverb consist of a thin metal plate suspended in a 4'x8' sound proofed enclosure. A transducer similar to the voice-coil of a cone loudspeaker is mounted on the plate to cause it to vibrate. Multiple reflections from the edges of the plate are picked up by two (for stereo) microphone-like transducers. Reverb time is varied by a damping pad which can be pressed against the plate thus absorbing its energy more quickly.
This is what a plate reverb sounds like [platereverb.mp3]
A spring reverb system uses a transducer at one end of a spring and a pickup at the other, similar to those used in plate reverbs, to create and capture vibrations within a metal spring. You find these in many guitar amps, but they were also available as stand alone effect boxes. They were a lot smaller than plate reverbs and cost a lot less.
This is a spring reverb [springverb.mp3]
The first reverb effects used a real physical space as a natural echo chamber. A loudspeaker would play the sound, and then a microphone would pick it up again, including the effects of reverb. Although this is still a common technique, it requires a dedicated soundproofed room, and varying the reverb time is difficult.
This is a chamber [Chamber.mp3]
These three types of reverb are all available in digital form in addition to a few other styles simulating real spaces, and others not found in nature.
Natural Reverb Types
Room - A room is anything from a classroom to conference room. There is generally a short decay time of about 1 second. [roomverb.mp3]
Hall – A hall is larger than a room, it could be from a small theatre with 1 second of decay up to a large concert hall with a decay time up to 2 and a half seconds. [Hall.mp3]
Church – The decay time of a church can vary between 1.5 seconds to 2.5 seconds. [Church.mp3]
And Cathedral decay times can go above 3.5 seconds. [Cathedral.mp3]
Remember, the sound of a room is not just the decay time. The materials it was built with make a huge impact on the character of the sound. Stone, wood, metal and tile all sound drastically different.
Unnatural Reverb Types
There's also a few other types of reverb that are not natural, these are Non Linear, Gated and Reversed.
Non-Linear has a decay that doesn't obey the laws of physics. [non-lin.mp4]
Gated reverb was a popular effect in the 80s, but it's sounding pretty cheesy these days. [gated.mp3]
Reversed reverb sounds like this [reverse.mp3]
Reverb Parameters
These are the common controls found on a hardware or software reverb effect
Reverb type - What kind of reverb emulation it is. There are Halls, Rooms, Chambers, Plates, etc.
Size - What the physical size of the space is. This can range from small through large.
Diffusion - How far apart are the reflections from each other.
Pre-delay - Sets a time delay between the direct signal and the start of the reverb
Decay time -Also known as RT60, which is how long it takes for the signal to reduce in amplitude 60 decibels.
Mix (Wet/Dry) - Sets the balance between the dry signal and the effect signal. When you have the reverb effect on an insert you need to adjust the wet and dry ratio, when you are sharing the reverb in a send and return configuration you want the mix to be 100% wet.
Early Reflection level - Controls the level of the first reflection you hear. Early reflections help determine the dimensions of the room.
Hi Freq. Roll Off - Helps control the decay of high Frequencies (as it's found in natural reverb).
Tips For Using Reverb
Using Pre delay can help keep your vocals up front, while still giving them space.
Try to keep decay times short for faster tempo music.
Filter out low frequencies before the reverb to keep it from sounding muddy
Try de-essing the reverb to reduce harsh sibilance.
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