Acid house

History and character

A subgenre born in Chicago in the mid-'80s around a single instrument: the Roland TB-303 Bass Line (produced 1981–84), a bass sequencer that failed as an accompaniment tool for guitarists and ended up second-hand in the hands of house producers. By raising the resonance, lowering the cutoff and programming accents, slides and octaves you get the "squelch" sound that gives the genre its name. Phuture (DJ Pierre, Earl "Spanky" Smith Jr., Herb J) recorded the 12 minutes of Acid Tracks on tape; Ron Hardy played it at the Music Box, sometimes several times a night, before Trax Records released it in 1987; Sleezy D — I've Lost Control (1986) was the first acid record released on vinyl. A curious forerunner is the Indian artist Charanjit Singh, who used the 303 in 1982 on "Synthesizing: Ten Ragas to a Disco Beat".

In 1987–88 acid house became a British phenomenon: Danny and Jenny Rampling's Shoom opened in London in November 1987, followed by Spectrum and Trip (Nicky Holloway, June 1988), and the raves in warehouses and fields; this was the "Second Summer of Love", with the yellow smiley as its symbol. The first British records: Baby Ford — Oochy Koochy (1988), Dougans/Stakker — Humanoid (1988), D Mob — We Call It Acieeed (1988). From October 1988 the tabloid press attacked the scene and some "acid" records were pulled from the radio.

Acid house gave rise to acid techno, acid trance and part of German trance (Hardfloor — Acperience, 1992), and today it lives on as a permanent revival (Roland TB-03, Behringer TD-3, plugins). Aesthetics: hypnosis from a single timbre that mutates in real time, minimalism, psychedelic euphoria.

Scales and keys

Convention: Roman numerals are relative to the major scale of the same tonic (uppercase = major, lowercase = minor, ° diminished, ø half-diminished, + augmented; b/# = degree lowered/raised relative to major: in A minor F = bVI, G = bVII). The notes and chords below are calculated exactly from the formula.

Aeolian (natural minor)

• Formula: 1 2 b3 4 5 b6 b7 — steps: W H W W H W W
• On A: A B C D E F G
• Diatonic triads: Am i · Bdim ii° · C bIII · Dm iv · Em v · F bVI · G bVII
• Seventh chords: Am7 i7 · Bm7b5 iiø7 · Cmaj7 bIIImaj7 · Dm7 iv7 · Em7 v7 · Fmaj7 bVImaj7 · G7 bVII7
• Characteristic note: b6 (F) and b7 (G): the acid line in A minor uses A, C, D, E, G with F as a tension note that falls to E.
• Use: the 303 riff in sixteenths over a single chord (or none): the "key" is given by the most repeated note and by the low register of the line.
• Common mistakes: too many different notes: the best acid lines use 3–5 notes and work on rhythm, octaves, accents and slides.

Phrygian (dark acid)

• Formula: 1 b2 b3 4 5 b6 b7 — steps: H W W W H W W
• On E: E F G A B C D
• Diatonic triads: Em i · F bII · G bIII · Am iv · Bdim v° · C bVI · Dm bvii
• Seventh chords: Em7 i7 · Fmaj7 bIImaj7 · G7 bIII7 · Am7 iv7 · Bm7b5 vø7 · Cmaj7 bVImaj7 · Dm7 bvii7
• Characteristic note: the b2 (F in E Phrygian): the semitone above the tonic, played with a slide, is the most "menacing" color of acid and acid techno.
• Use: riffs that oscillate between E and F, E1–E2 octaves with F as a passing tone; the bII chord (F) as an occasional stab.
• Common mistakes: using the b2 on a strong downbeat and holding it long: it should be an accented or slid passing tone.

Minor pentatonic

• Formula: 1 b3 4 5 b7 — steps: W+H W W W+H W
• On A: A C D E G
• Characteristic note: no semitones: all the notes are "right" over a pedal.
• Use: the simplest way to a 303 line that always works: A–C–D–E–G over two octaves.
• Common mistakes: staying in the mid register: the 303 must live between A1 and A3.

Blues (chromatic b5)

• Formula: 1 b3 4 b5 5 b7 — steps: W+H W H H W+H W
• On C: C Eb F Gb G Bb
• Characteristic note: the b5 (Gb), a chromatic passing tone between 4 and 5 that, with a slide, creates the acid "lament".
• Use: F–Gb–G slides, funk bass phrases.
• Common mistakes: using the b5 as a long anchor note.

How to choose between the scales

Acid house is modal and monotonal: you pick a tonic and build a 16-step pattern. Minor pentatonic = safe and funky; Aeolian = more melodic; Phrygian = darker and closer to acid techno; blues = funk chromaticism. The scale matters less than the programming: accent (which notes are stronger and more open on the filter), slide (tied notes that glide), octave (jumps up/down) and the hand on the cutoff over time.

Harmony

Function

Often absent: the track is built on a pedal (the tonic of the 303 line) and the drums. When there are chords, they are minor stabs or pads on 1–2 chords.

Techniques

• A single minor chord (Am7 or Am9) held or in stabs, while the 303 draws the mode.
• Two chords a whole step or semitone apart (i–bVII, i–bII) for tension.
• Pads in open fifths (A5) so as not to pin down the mode.
• Chromatic borrowings implied in the line (b2, b5).

Harmonic rhythm

Very slow: one chord per 8–16 bars or for the whole track. The perceived "harmonic movement" comes from the 303's filter opening and closing (it changes the harmonics, not the notes).

Examples

• Phuture — Acid Tracks: just drums and 303 throughout.
• An Am9 stab every 2 bars over a line in A.

Typical progressions

Rhythm and groove

• Grid: the 303 plays in sixteenths (16 steps per bar), the pattern is 1 or 2 bars long (16/32 steps), sometimes with odd lengths (12, 15 steps) that shift out of phase against the kick.
• Feel: straight or with light shuffle (52–56% MPC; FL Studio 10–25) on the percussion; the 303 is usually straight, but the slide shifts the perception of the attack.
• Accents: the 303's accents create a second groove: place them on 3–5 asymmetrical steps (e.g. steps 3, 6, 11, 14).
• Variation: the notes don't change; the timbre changes (cutoff, resonance, env mod, decay, accent) by hand in real time.

Drums

Kick

On quarters, TR-808 or TR-909; in the more "rave" British acid, a 909 with more click. Always on the grid, no variation. Length 200–350 ms; if the 303 goes below 60 Hz, shorten the tail.

Clap and snare

Clap on 2 and 4; 909 snare in end-of-phrase rolls. In the more minimal tracks the clap may be missing and there is just a rim.

Hi-hat and ride

909 closed hat in sixteenths with accents, open hat on the offbeat; 909 ride in the full sections. Dry hats (909 6-bit) that don't compete with the 303 (which has harmonics between 1 and 5 kHz).

Percussion

Few: 808 cowbell, clave, rim, 727 congas. They serve to counterpoint the 303, not to fill.

Dynamics and groove

Fixed patterns; dynamics come from the drum machine's accents and from lanes entering/exiting. The real rhythmic "soloist" is the 303.

Interaction with bass and vocals

The 303 is bass and lead together: avoid notes on the kick at steps 1, 5, 9, 13 if the line is low; otherwise light sidechain. Vocals are often just samples ("acid!", "jack").

Sections

Drum intro; the closed 303 enters; the filter opens over 16–32 bars; a break with no kick, with 303 and reverb; re-entry with the 303 open and distorted.

Fills

909 rolls of 1–2 bars, a 1-bar stop, crash.

Typical mistakes

Drums that are too full and cover the 303; modern hats that are too bright; no 303 automation (the pattern gets boring after 16 bars).

Bass

• Sound: TB-303 or clones (TB-03, TD-3, ABL3, Phoscyon, Audiorealism, or in FL Studio the stock plugin 3x Osc or Sytrus/Harmor set up as a 303). Saw oscillator (more aggressive) or square (hollower); 4-pole resonant low-pass filter (nominally 24 dB/oct, but with a particular response that many describe as softer, ~18 dB/oct), filter envelope with decay only; the accent raises volume and filter opening and shortens the decay; the slide ties two notes with a glide of about 60 ms (indicative value).
• Range: A0–A3; the most expressive part sits between 100 Hz and 3 kHz.
• With the kick: if the 303 is low, add a separate sub (sine) that plays only the tonics on the offbeat; otherwise the 303 itself is the bass, with 2–3 dB of sidechain.
• Notes: 3–5 notes of the scale, octaves up and down, b2/b5 as slid passing tones.
• Rhythm: sixteenths with rests, irregular accents, slides on 2–4 steps per pattern.
• Example programming (A minor, 16 steps): A1 · A1(acc) · A2(slide) · G1 · A1 · · C2(acc) · A1 · D2(slide) · E2 · A1(acc) · · G1 · A2(slide) · A1 · E1.
• Typical starting parameters: cutoff 25–35%, resonance 60–85%, env mod 50–70%, decay 30–50%, accent 50–80%. Then automate cutoff and env mod over time.
• Distortion: often after the 303 (pedal or saturator): from a little (warmth) to a lot (rave acid).

Harmonic instruments

• Pads: Juno or Prophet with slow attack, minor chords or fifths, in the breaks.
• Stabs: short m7/m9 chord stabs, with delay.
• Piano: rare; in some UK tracks, piano house + 303.
• Organ: M1 organ stabs in 1988–90 productions.

Secondary role: everything has to leave room for the 303 between 300 Hz and 3 kHz. Mid-high register (C4–C6) or under the 303 as a distant pad.

Melody and vocals

• Lead: the 303 itself, or a second 303 an octave above.
• Vocals: spoken or shouted samples, often a single word; soul vocals in the vocal versions.
• Additional melodies: simple synth or piano riffs, rare.
• Effects: tempo-synced delay (dotted 1/8, 3/16) and reverb on the 303 in the breaks; distortion; occasional phaser and flanger.

Instruments

Roland TB-303 (or clones), TR-808, TR-909, TR-707/727, Juno-106, SH-101, Korg M1 (organ and piano), samplers (Akai S900/S950), pedal distortions (Boss DS-1, ProCo RAT), digital delays, cheap mixers.

Drum patterns

Synths and sounds

• Mini V — Alternative acid line: A single saw oscillator, 24 dB ladder filter with high resonance (60–80%), high env amount, decay 150–250 ms, sustain 0; short glide (legato on) only on overlapping notes to simulate the slide. Rounder and fatter than a 303.
• SEM V — Alternative squelch: The SEM's 12 dB multimode filter in low-pass with high resonance gives a softer squelch; useful for "deep" acid lines.
• Korg MS-20 V — Aggressive acid: The MS-20's filter with high resonance and a little overdrive gives a sharper acid; great for rave versions.
• Jun-6 V — Pad and stab: Pads with Chorus II and 300–600 ms attack for the breaks; short stabs with 200 ms filter decay.
• Modular V — Experimental acid: Sequencer, saw VCO, ladder filter and a VCA with a separate accent: lets you rebuild the 303's logic (an accent that modulates filter and volume together).

Song structure

Long tracks (6–12 minutes), designed to evolve slowly. Phrases of 8 and 16 bars.

The rule: the 303 should sound different every 8 bars even if the notes don't change. Record the cutoff/env mod/decay automation by hand, as in a live performance.

Mixing and mastering

Sonic goal

The 303 is the protagonist and must "bite" without hurting: present between 500 Hz and 3 kHz, with resonance that doesn't explode at volume. Drums solid but secondary. References: Phuture — Acid Tracks; Hardfloor — Acperience 1; DJ Pierre; for modern acid, recent productions on labels like Acid Waxa or Balkan Vinyl.

Kick

• EQ: HP 30 Hz, fundamental 50–60 Hz +2 dB, cut 250–350 Hz −3 dB.
• Compression: VCA 4:1, attack 15–25 ms, release 80 ms, GR 2 dB.
• Saturation: light tape. Space: dry. Stereo: mono.

Clap and snare

• EQ: HP 200 Hz, +2 dB at 1–1.5 kHz, watch 2–3 kHz where the 303 lives (cut −1/−2 dB if they clash).
• Compression: fast 4:1, GR 3 dB. Space: room 0.8 s, pre-delay 10 ms.

Hi-hat and percussion

• EQ: HP 500 Hz, shelf +1 dB at 10 kHz; below 4 kHz they must be clean to leave room for the 303.
• Panning: hat 15% L, perc on the sides. Space: dry.

TB-303 (bass/lead)

• EQ: HP 30–40 Hz; if it also plays as the bass, keep 60–150 Hz; dynamic EQ (Pro-Q 3 or Fruity Parametric EQ 2 + automation) that reduces the resonance peak by 3–6 dB when the filter passes between 1 and 3 kHz; LP at 8–10 kHz if the distortion generates too many highs.
• Compression: fast compressor (FET, 4:1, attack 1–3 ms, release 50 ms) or light limiter to contain resonance and accent peaks (GR 3–6 dB).
• Saturation/distortion: overdrive/distortion pedal (Fruity Blood Overdrive, Decapitator "N" or "P", Saturn 2 "Heavy"), dosed at 30–100% mix; EQ again after the distortion (remove excess 200–400 Hz).
• Space: 3/16 or dotted 1/8 delay on a send with HP 300 Hz and LP 5 kHz, feedback 30–50%; 1.5–2.5 s plate reverb only in the breaks (send automation).
• Stereo: the dry line in mono in the center; delay and reverb wide.
• Automation: cutoff, env mod, resonance, decay, accent, delay send, drive.

Sub (if present)

Mono sine 40–80 Hz, HP 25 Hz, LP 120 Hz, sidechain 4–6 dB from the kick.

Pads and stabs

HP 200 Hz, cut 1–3 kHz so they don't cover the 303; 2–3 s hall, wide; sidechain 4–6 dB.

Vocals and samples

HP 120 Hz, compression 4:1 (4 dB GR), 1/4 delay throw, short plate; center.

FX

Risers and noise with HP 300 Hz; reversed 303 in the breaks.

Buses and groups

Drum bus with 2:1 glue (GR 2 dB); 303 on a dedicated bus with saturation and compression; FX bus for delay/reverb with sidechain.

Sidechain

Pads and reverbs 4–6 dB from the kick; 303 only 1–3 dB (too much sidechain breaks the line's groove).

Master

Chain: EQ (HP 25 Hz) → bus compressor 1–2 dB → light clipper → limiter. Target −9/−7 LUFS integrated (modern acid up to −6), true peak −1 dBTP (−0.3 for club), crest factor 8–10 dB. Check that the resonance peaks don't make the limiter work audibly.

Common mistakes

Uncontrolled resonance (whistles at 2–3 kHz at high volume); distortion that fills the whole spectrum; sub and 303 in the same octave without separation; no automation; unfiltered delay that muddies things.

Reference tracks for mixing

• Phuture — Acid Tracks (1987)
• Hardfloor — Acperience 1 (1992)
• Josh Wink — Higher State of Consciousness (1995)

Reference listening

• Charanjit Singh — Synthesizing: Ten Ragas to a Disco Beat (1982, album)
• Sleezy D — I've Lost Control (1986)
• Phuture — Acid Tracks (1987)
• Baby Ford — Oochy Koochy (1988)
• Stakker — Humanoid (1988)
• D Mob — We Call It Acieeed (1988)
• Hardfloor — Acperience 1 (1992)
• Josh Wink — Higher State of Consciousness (1995)