Chamber, Plate, Hall...What Do I Use?
All Exponential Audio reverbs provide a large selection of presets. Leaving rooms aside for the moment, most of the reverbs are based around variants of Chambers, Plates or Halls. And of course, any user may easily change the underlying type with a quick edit. So what's the difference? And why would I choose one over the other?
All of these types have historical precedents, with the Hall as the first example. The concert hall as we know it now is a creation of the 19th-century. Earlier performances took place in ballrooms, churches or other spaces not necessarily created with music in mind. When music began to be performed for the general public, spaces were built that could accommodate a few hundred listeners. While the following decades brought many refinements, the basic idea of a hall is still what it was then--a rectangular space with a lot of seats. Acoustically, this means fairly long propagation times and slow reverb buildup. It also allows reverberation of long wavelengths, with a typically robust low frequency component.
Next up was the chamber in its most basic form--a bathroom or stairwell with a mic and speaker. It was an effective way to make a reverb--as long as the environment remained quiet. Over time, a number of purpose-built chambers found their way into studios. Notable examples include those at Abbey Road and Capitol Records. Because a chamber is usually very small, the reverberation reaches maximum density very quickly. Low frequencies are typically problematic and are usually constrained by EQ in the chamber electronics.
Finally we have the plate. A plate is what it sounds like--a large metal plate (about one meter by two) with transducers attached. It's the quickest to respond of all systems, and is typically the most diffuse. It's quite sensitive to its suspension (a system of springs) and can show huge variability from one plate to the next.
There really aren't hard and fast rules about what to use, but there are reasons that mixers lean in one direction or another. Because of its long propagation time, a hall is seldom used on percussion instruments. The first 'bounces' of a strong transient are quite audible and are usually very distracting. This can be reduced by increasing diffusion or dialing in a smaller room size. But usually another reverb architecture is a better choice. A chamber works well for percussion. By its nature it's more diffuse and discrete reflections are seldom a problem. A plate is also a good choice and is usually the most popular selection. While not actually realistic, a plate can be very flattering to a snare drum or to a piece of hand percussion. If you have favorite mixes, it's always worth trying to learn about what was used for the mix.
For other types of audio sources, your selections can be more open. Horns in popular music respond well to plates. Synth pads may work nicely in plates or chambers. Voice can work in anything, depending on the overall sound you want. The discrete bounces of a hall--the same bounces that may be distracting for percussion--can provide a subliminal pulse that makes a voice sound huge on a ballad. But again, there's nothing like studying mixes you like and trying to identify the signatures of the various reverb types they used. Real plates, chambers and halls are still very much a part of modern music-making.
A final word about rooms. Rooms in Exponential Audio are built on any of the reverb types. There's a tutorial right here that can teach you more. Rooms are used in mixing for many different purposes. Sometimes you may want a room for an intimate mix--something that's balanced and musical. At other times you may need one for foley work in a film, when musicality isn't part of the, ahem, picture. Many of the Exponential Audio rooms have intentional coloration that works beautifully in one situation and terribly in another. For that reason, experimentation is recommended. The room that's perfect for a Strat/Marshall might be just the wrong thing for a Les/Twin.