You probably know how to make a reese bass/supersaw with a synthesizer (play two or more sawtooth waveforms which are subtly out of tune), but have you ever wondered why they make their distinctive sound? Read on, as Lu talks through some of the basics of synth detuning and how it all works.
For a start, note that this deals with the “classic” form of a reese; in drum & bass circles, the term has come to be used as something of a catch-all to describe any sort of heavily-processed bass synth. For an example of what this article is discussing, be sure to check out the track “Bristol Transmission” and listen to the bass synth which comes in at the 22 second mark.
The reese has a sense of movement and depth about it, compared to the otherwise tinny or raspy-sounding single sawtooth waveform. The added dimension of the reese is a product of phase cancellation.
Speakers generate sound by moving in and out of their housings, with audio waveforms being very consistent movements for whichever note/frequency is being played. Phase describes the position of the waveform within its repetitive cycle.
For example, a sawtooth begins with a sharp jump upwards followed by a straight, steady drop in the opposite direction (this is actually a visual representation of the speaker’s movement out and in to produce the sound). This movement is cyclical in nature, starting over each time the waveform reaches its end.
What imparts the sense of depth and movement to the reese is the fact that multiple waveforms are played at once, each slightly different in frequency (the number of times they complete their cycle each second).
If all of this seems a little confusing, try open opening up a DAW, and load up a synthesizer with two sawtooth oscillators at the same pitch, feeding into an oscilloscope plugin (a number of free plugins exist for oscilloscopes, my favorite being the MOscilloscope included in Melda Productions’ free plugin suite).
Play a single long, repeating note and watch it through the oscilloscope. The scope should display a continuous sawtooth.
To see the reese in action, begin detuning one of the oscillators, and watch as the scope display begins to undulate in size. The change in size is a product of the two waveforms going in and out of phase.
With the waveforms out of sync, they will start and end at different stages relative to one another. Think of it like runners doing laps around a track; if they complete laps at different times, they will end up at different places on the track, independent of one another.
Phase cancellation is a result of the fact that a speaker cannot be in two places at once, and air cannot move in opposite directions at once. With the waveforms repeating at different speeds, there will come to be points where they compound each other’s volume, but also points where they cancel each other out, as they are pulling against one another.
