Room vs Hall
Room reverb, as the name suggests, is closely related to a Hall reverb. They are both designed to simulate the natural sound of acoustic spaces. The main difference between them is that rooms are smaller spaces, which means that sounds travel much faster thru them and the decay is always quicker.
When it comes to instruments that are recorded with really close microphone positioning, the room can be the right choice in order to add some realism. The instruments which can benefit from processing with room reverb are definitely guitars and drums. Furthermore, Room gives the impression that the instrument is played in a real acoustic space.
Slap Delay Replacement
Room reverb can also be used as a substitute for slap or echo delay effects. This can be done easily by keeping the room reverb`s time short and relatively long pre-delay time. This is usually done in order to make slap/echo effect sound more realistic, especially if the mix contains the majority of real instruments. Nevertheless, it should be used with caution. The reason for this is mainly because if room reverb is used to much in the mix, the result will be a boxy/small sound. Another problem is the choice of a Room reverb. If you use a less sophisticated unit, it can add unwanted resonances in the mix. This definitely doesn’t go well musically.
Modern Room Reverb
Nowadays, the available Room reverb units are quite scarce. In hardware and software worlds, they usually exist as combo reverb units. Inside you can switch between room, hall and plate type of reverb. Digital units are most common when it comes to room reverb simulators, both hardware, and software.
In recent times, one of the better-designed software Room reverbs is definitely the ValhallaRoom plugin. It is a full stereo room reverb unit that, firstly, realistically mimics real acoustic spaces. The GUI is designed for easy navigation. In addition, the Early and Late reverb sections are both stereo-in and stereo-out. The spread of energy between the stereo channels can be controlled over time, which helps preserve the input spatial image. It also possesses 12 unique reverb algorithms.