The Curse Of The Resonant Studio
In my last post I advised that it may not be necessary to purge your home studio of all external sound – in fact, room sound may be beneficial to your recordings. However, it’s also a good idea to test for obtrusive resonances, as these can impair your ability to accurately balance a mix…
Check For Room Modes
The resonances that occur within an enclosed space, such as a studio, are referred to as modes. If you have a room that is 16 feet long, the fundamendal mode will occur at 35 Hz, as this is the frequency of a sound wave with a wavelength of 16 feet. Additional modes will occur at multiples of this base mode, just as harmonics occur in music.
If this hypothetical room is also 8 feet wide, then this creates another set of room modes which will interfere with (and exaggerate) any problems caused by the original mode. In fact, the worst room length:width:height ratio is 1:1:1, as this will cause triple magnification of the fundamental mode.
The Problem With Frequency Reinforcement
When you play a note that is a multiple of the room mode, it will sound louder than other notes. The resonance of the room also means that such notes will have a longer sustain and delay time, which can lead a producer to compensate for problems in the mix that are actually in the room itself.
If you would like to perform a quick check of your studio for resonances, Des at Hometracked has a useful post which provides a few audio files aimed at this very task. You can use these recordings to test for problem notes as well as panning issues with your current monitoring setup.
Another useful resource for identifying room modes is this mode calculator – you can enter the dimensions of your studio and it will provide a graph indicating likely problem frequencies. If you have the luxury of building your own studio, you can also use this tool to decide the best room size ratio to use for your project.
Designing An Ideal Recording Space
Rooms designed for recording have many modes distributed fairly evenly. This is preferable to having a few modes at irregular intervals, as is the case with small rooms – because in a small room, the fundamental mode appears at a higher frequency. Large rooms have fundamental modes at a lower frequency, which means that all additional modes are closer together. If the fundamental mode is 20 Hz, then other modes occur at 40 Hz, 60 Hz, 80 Hz – but if the fundamental is 55 Hz (as in the case of a 10 foot room) then the modes are 55 Hz apart – 110 Hz, 165 Hz, 220 Hz, and so on.
Therefore, in agreement with the opinions of Brian Eno and Tim Prebble referred to in the previous post, an ideal recording studio should be as large as possible. If this isn’t an option, then it might be time to get a few extra bass traps.