Machine and soul
Analogue drum machines were plentiful in the 70s and early 80s, ranging from the initial pre-programmed accompaniment add-ons and built-ins to the now classic purpose-built beat boxes made by Roland et al. Virtually all of them produced their sounds via the same methods, which were culled from analogue synthesis. The basic drum sounds used for kicks, toms and other timbres were derived from filters with high resonance levels. These filters could be excited with a short, percussive envelope that would push them over the brink into self-oscillation. This is very similar to the method we will be using in our tutorials, the one difference being that software synthesisers often lack selfoscillating filters. No matter, though – we can make them work all the same.
Noise is another important ingredient in electronic drums. From hi-hats to snares to toms, there are few drum sounds that don’t have an element of noise. This is, of course, most apparent in snare drums, with their rattling wire snares. Handclaps can be fashioned almost entirely from filtered noise. Some drum sounds can be made without noise, but even these can be spiced up with an almost imperceptible burst of noise at the attack stage.
Obviously, envelope generators are vitally important for drum patches. Most commonly applied to amplitude, these control the level of the signal over time. The four-stage ADSR envelope is by and large the most commonly used. ADSR is an acronym that describes each stage: the ‘attack’ determines how fast the sound achieves maximum level; the ‘decay’ specifies how long it takes that maximum level to fall to the held, steady state, or ‘sustain’, which is what the sound does while a key or note is held; and the ‘release’ governs the length of time the sound will take to fade to silence once the note is released. A well-thought-out envelope shape can be the making of any drum patch – the previously mentioned noise burst, for example, requires an instantaneous attack and a small amount of decay, while a handclap calls for multiple attack and decay phases.
“A well-thought-out envelope shape can be the making of any drum patch”