Dubstep

What it is

Forward>> ran on Thursdays at the Velvet Rooms on Charing Cross Road from 2001, and by about 2005 what got played there had a name and a fixed shape. The tempo stayed at the 140 garage had left behind, but the snare moved: once a bar, on beat 3, which halves the felt tempo without changing the count. Everything above the drums keeps moving at 140, so the hats and the modulation on the bass run at one speed while the body of the record moves at another, and that doubling is the engine of the genre. The bass took its wobble from a filter LFO synced to an eighth or a dotted eighth. The sub went low enough that the music only makes complete sense on a rig with eighteen inch drivers, which is why the early scene was a soundsystem scene before it was anything else.

What it sounds like

Enormous and mostly empty. A sub sine holds a note under a mid-range growl that opens and closes in time, so the low end and the mid are the same instrument split across a filter. Snares are big, dark and reverbed, sitting alone in the middle of the bar with room to ring. Kicks are long and tuned. Above that, very little: a sampled vocal fragment, a minor pad, some field recording. Delays are eighth-note and dubby, reverbs are long and heavily filtered, and the region between 300Hz and 2kHz is kept clear so the bass has somewhere to scream when it opens up.

Key elements

• The snare on 3One backbeat a bar. It is the single decision that separates this from grime at the identical tempo, and everything else in the arrangement follows from it.
• The LFO wobbleA low-pass filter on a saw bass, cutoff driven by an LFO locked to an eighth or a dotted eighth. Change the LFO rate every two bars and you have written an arrangement.
• Sub under 60HzA sine an octave below the growl, mono, playing the actual note. On small speakers you hear the mid-range; on a rig you feel this instead.
• Offbeat eighth hatsHats on the ands, with the odd ghost elsewhere and never on a downbeat, which keeps beat 1 clear for the kick and stops the top end filling the half-time space.
• Two speeds at onceDrums at 70, modulation at 140. Keeping both audible at the same time is the craft in this music and the reason it survives at length.

How to get them

• BassTwo saws detuned about 12 cents into a 24dB low-pass, cutoff around 400Hz with an LFO swinging it two octaves at an eighth. Split a mono sine under 80Hz off underneath, unfiltered.
• SnareA layered acoustic and electric snare tuned down two semitones, with a 2.5 second plate high-passed at 500Hz behind it. Let the tail ring into the next kick rather than gating it.
• KickLong decay, around 300 milliseconds, tuned to the root. Sidechain the bass to it by 4dB with a 60 millisecond release so both fit through the same speaker.
• HatsOne closed hat sample, offbeat eighths, alternating 72 and 58 so the bar has a shape. Keep the whole lane 12dB under the snare.
• Mono below 100HzSum everything under 100Hz to mono before the master. A stereo sub cancels itself on a club rig, and this music is not worth making if the bottom folds down.
• Swing50 percent, straight. The lurch in dubstep comes from the LFO and the empty space, not from moving the sixteenths off the grid.

Reference points

Digital Mystikz, Skream, Benga, Loefah, Kode9, Distance and Pinch, and the Tempa, Hyperdub, Big Apple and Hotflush catalogues. Named as reference points for the sound, not as endorsements.