Reese bass

Press Hold A1 below and let it sound. The note growls, and the growl keeps turning over, slowly, like something breathing under the floor. Nothing is moving the controls. That's a Reese bass, whose classic recipe is two saw waves a hair apart in pitch. It's named after Kevin Saunderson's 1988 Detroit record "Just Want Another Chance", released under the name Reese, and in the 1990s jungle and drum and bass producers turned it into the dark, rolling bass line of a whole genre.

Before you build it: do you think you need an LFO to get that movement, or can two nearly matching notes make it on their own?

1. Start with two identical saws

Both oscillators start on exactly the same pitch. Hold A1. It's a plain, buzzy bass, and the shape on the scope sits still. Two copies in step sound like one louder copy.

Why: Oscillators and waveforms explains why a saw is packed with harmonics for the copies to play with.

2. Move one a few cents

Raise Osc 2 Fine to about 6, then 12. The scope shape starts to slide and the sound starts to turn over. Now you hear the Reese: the two saws keep drifting in and out of step, so their harmonics add up, cancel and add up again.

Here's the part that makes it growl rather than pulse. A cent is a fixed ratio, so the gap in hertz is bigger for each harmonic up the series. At 12 cents on A1 the fundamental swells and fades about once every three seconds, while the fifth harmonic does it almost twice a second, and higher harmonics faster still. Every layer of the sound is moving at its own speed.

Keep going past 25 cents and the swirl turns into a sour, out-of-tune chord. Somewhere between 5 and 15 cents is where most Reese basses live.

Same idea, different place: a supersaw uses the same beating with more copies higher up. Gamelan-inspired texture uses paired tones in a metallophone model. Compare its steady shimmer with this bass's rolling growl.

3. Darken it

A raw saw this low can fizz on top. The table here morphs from a sine to a saw, so Position works like a tone knob: lower is darker, higher is brighter. In the synth at the top, try Position around 0.5 for a rounder, more menacing growl, or 0.8 for a nastier, brighter one. Change both oscillators' Position together so they stay matched. Now the movement sits in the low mids, where it sounds heavy rather than buzzy.

Why: Subtractive synthesis is the usual way to darken a saw, with a low-pass filter; this table gets there by changing the wave itself.

4. Listen for the dip

Hold a note and listen only to the very bottom. Every couple of seconds the low end thins out: that's the fundamental cancelling, the dip marked in the figure. On big speakers it reads as part of the groove. Under a kick drum it can make the bass feel unsteady. If that bothers you, reduce the detune a little, or play shorter notes so the dip rarely arrives. Now the low end holds while the top keeps moving.

Many drum and bass producers solve this by adding a separate, plain sine an octave down to carry the low end, with the Reese on top for character.

Why: Low end is about keeping the bottom steady while the rest of the sound moves.

5. Play a line

Play a slow, two-note riff low on the keyboard, then the same riff higher. High up, the swirl gets faster and busier, because the gap in hertz grows with pitch. Pick the register where the movement feels like a groove rather than a flutter, and shorten Release if one note's tail runs into the next. Now you have a bass line, not only a sound.

Why: Envelopes covers how the end of each note leaves room for the next.

Keep it

Press Save in the bar under the synth at the top and call it "Reese". Next time a track needs weight with some menace in it, it's there, and you know the two controls that change its character: Fine for how fast it swirls, Position for how dark it growls.

Quick check

1. Your Reese sounds great on a low note and frantic an octave higher. Why? Cents are a ratio, so the same detune gives a bigger gap in hertz on higher notes, and faster beating. Reduce the detune for higher lines, or keep the bass low.
2. The bass feels like it drops out every couple of seconds under the kick. What's happening? The two fundamentals are briefly cancelling. Less detune makes the dip rarer; a separate plain sub underneath fills it. Turning the bass up doesn't help, because the dip is still there, only louder around it.
3. A friend adds an LFO to the pitch to "make it move". Do you need one? No. The detune already moves it. An LFO can add a second, slower motion on top, which is a fine creative choice, but the classic Reese is two oscillators and nothing else.

Next steps

• Use it: Stereo and spatial processing. Keep the motion wide while checking that the bass survives mono.
• Go deeper: Tuning systems. Hear how the gap between two pitches sets the speed of their beating.