Acid bassline (303)
An acid bassline is a busy sixteenth-note synth line played the way the Roland TB-303 plays: some notes accented, some sliding into the next, all through a resonant filter that squelches. It is the sound of acid house and acid techno, at about 120–135 BPM.
Also called acid bassline, acid line, TB-303 bassline, 303 acid.
Play it
- Bar 1Am
- Bar 2F
- Bar 3C
- Bar 4G
Faded lanes are a guide: they are there so the pattern has something to sit against. The loop runs over four chords, Am, F, C, G, one bar each. Tap any box to change it.
Try this
Try this · change one box
Tap the octave note on step 3 to take it out. The first slide goes, and the line sits on the root for longer before it moves.
Learn this pattern step by step
The course builds up to it from Unit 1, which is free with a Google sign-in. It plays in your browser, like this page.
Pick up where you left off
Carry on with Unit 1, then Acid bassline comes in Unit 8: Sound.
Hear it without the grid
A short recording of the loop above at 128 BPM, made with Swung’s own sounds.
How it works
Three things make it acid. Accents: the loud notes open the filter wider, so they bark. Slides: some notes glide into the next instead of jumping. Resonance: the filter rings at its edge, and that ring is the squelch.
Here the line moves between the root, the octave above and the fifth, sliding up to the octave on steps 3 and 11 and back down on the next step. The notes are simple; what you hear is the filter moving.
The pattern in words
- Root: steps 1, 6 and 9; quiet on 2, 4, 8, 12, 13 and 15 of 16.
- Octave: steps 3, 11 and 16 of 16.
- Fifth: step 14; quiet on 7 of 16.
| Part | Steps, 1 to 16 | Plays on |
|---|---|---|
| Root | xo·o·x·ox··oo·o· | steps 1, 6 and 9; quiet on 2, 4, 8, 12, 13 and 15 of 16 |
| Octave | ··x·······x····x | steps 3, 11 and 16 of 16 |
| Fifth | ······o······x·· | step 14; quiet on 7 of 16 |
x a hit, o a quiet hit, 2 or 3 a quick roll inside one step, – a note held on, · nothing.
Variations
No slides
The same notes, jumping instead of gliding.
No accents
Every note at the same level, so the filter never barks.
Down an octave
The same line an octave lower: darker, more of a bass.
Where it’s used
Also common in Acid house, Acid techno and Trance.