Acid techno is a small number of parts locked together: a driving four-on-the-floor kick, a squelchy TB-303 style acid line looping over the top, offbeat hats and claps, and a track that changes slowly enough to feel hypnotic. Here is what each part is and how they fit.
Works in any DAW, with any 303-style synth, hardware or software. Nothing here needs a particular plugin.
The acid is one ingredient: a TB-303 style bassline with accent, slide and a resonant filter that squelches as it moves. Take that line out and you have ordinary techno. Put it back and the whole track reads as acid, because nothing else sounds quite like it.
Everything else is straight-ahead techno holding the floor steady so the 303 can wander over the top. The ingredients are consistent from track to track:
The 303 is what earns the name, but the kick and the groove are what make it move. Get the floor steady first, then let the acid line squirm over it. Most of the settings people ask about live in a small range:
| Part | Typical | What it does |
|---|---|---|
| Tempo | 130 to 150 BPM | Fast and driving, the techno end of the dance floor |
| Kick | Four on the floor | One hit on every beat, steady and hard, the anchor |
| 303 line | Short minor pattern | A few notes in a minor scale, looped until it locks |
| Accents | 3 or 4 a bar | Louder and brighter notes that give the squelch its shape |
| Slide | A couple of notes | A glide between steps for the liquid, vocal feel |
| Filter | High resonance, moved slowly | The sweeping squelch, opened over many bars |
| Distortion | After the filter | Overdrive that gives the 303 its bite |
Write a short pattern in a minor scale, accent three or four steps, slide between a couple of notes, then open a resonant filter slowly over many bars. The accent and the slide are what make it sound like acid rather than like a plain filtered bass.
An acid line is a short cell, usually three to five notes, in a minor scale, looped until the ear locks onto it. The repetition is the hook. Keep the line inside about an octave and let the accents provide the movement rather than big leaps, then an octave jump once in a while lands as an event instead of as more of the same.
An accented step is louder, and it also pushes harder into the filter, so it opens brighter and snaps back. That louder-and-brighter on the same note is the squelch, and it is the signature. Slide is a glide between two consecutive notes: it ties two steps into one longer gesture and gives the liquid, vocal quality. A few of each per bar is plenty. Accent every step and none of them stand out.
There is a full walkthrough of writing the part in the acid bassline guide, which goes deeper on where to put the accents and how far to slide.
Turn resonance up, around three quarters, so each note starts to whistle. Set the cutoff low and let the note envelope open it, then move the cutoff by hand slowly, over eight or sixteen bars, for a slow reveal rather than a constant wobble. Put distortion or overdrive after the filter, on the output, not before it, where it just muddies the low end. The overdrive on the output is a large part of the classic recorded sound.
A four-on-the-floor kick on every beat, offbeat hats between the kicks, and a clap or snare on beats 2 and 4. Keep it steady and driving so the 303 has a firm floor to move over.
One kick on every quarter note is the engine of the track. Keep it steady and punchy and do not let it change much; it is the anchor that everything else leans against, and the reason the groove feels relentless rather than busy.
Put closed hats on the offbeats, the sixteenths between the kicks, to drive the groove forward. A clap or a snare on beats 2 and 4 gives you the backbeat. An open hat on an offbeat adds lift when a section needs a push. None of this is complicated, and it is not meant to be; it is there to carry the 303, not to compete with it.
The kick and the acid line both live low, so they fight if they both hit hard on the same step and the bottom of the mix turns to mud. Leave the step where the kick lands empty in the 303 pattern, or put an unaccented note there, and put the accents on the offbeats. The two parts then interlock instead of colliding.
Change slowly. Acid techno tracks are long and repetitive on purpose, so the movement comes from gradual changes: sweeping the filter, pushing the distortion, and dropping parts in and out over many bars rather than every few.
The repetition is the point, not a problem to solve. A pattern loops long enough that the ear stops counting the notes and settles into the groove, and that hypnotic state is what the slow changes then play with. If everything moves at once there is nothing steady to hear the movement against, and the track reads as fidgety rather than deep.
Loop the kick and the 303 line on their own and leave it playing for a minute. If the two of them already lock together and pull you in, the track will work. If it bores you before the minute is up, no amount of filter sweeping or distortion will save it, and the fix is in the pattern and the accents.
The awkward part of acid is that the good lines usually arrive by accident while you are playing with a sequencer, and then you have to get them into an arrangement. Recording the audio locks in every decision at once. What you usually want is the notes, so you can change the sound later.
REHEAT is an acid instrument that writes the line for you, accent and slide included. Find a pattern you like and you have two ways to use it: drag the MIDI straight onto a track in your DAW, or play it live through your own synth with the REHEAT MIDI DRIVER. Either way the notes are yours to keep. Change the key, change the sound, edit the accents by hand.
That is the point of writing the part rather than printing the audio. An acid line is worth more as notes than as a recording, because the notes survive every later decision about the sound and the arrangement.
Free to hear in the browser, no signup. It runs as an Audio Unit, a VST3 and an AAX. Everything above still works by hand in any DAW too, which is rather the point of writing it down.
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