How to make an acid (303) bass in Serum 2

The acid sound is a single saw or square wave through a resonant low-pass filter, with a short envelope that snaps the filter open on each note, and notes that slide into each other. Most of what makes it acid is in the filter and in how the pattern is played.

Oscillator and voicing

  1. Set oscillator A to a saw (or a square for a hollower tone). One voice, no unison.
  2. Switch the voicing to mono and turn on legato.
  3. Set portamento to around 50 to 80 ms. With legato on, only overlapping notes slide, which is how the 303 slide works.
VISIONS OF TOMORROW71 finished Serum 2 presets for house and techno: 26 basses, leads, pads, plucks, keys, stabs and FX. Royalty-free.Requires Serum 2.

The filter does the talking

  • Route the oscillator to a 24 dB low-pass filter.
  • Set the cutoff low, so the bass is dark with the envelope off.
  • Raise the resonance high, until the filter almost whistles.
  • Drag ENV 2 onto the cutoff with a short decay (100 to 250 ms) and no sustain. Each note now opens the filter and closes it again.
  • Map the cutoff and the envelope amount to two macros. Turning them slowly while the pattern plays is the acid sound.

Velocity is a good stand-in for the 303 accent: route velocity to the envelope amount so loud notes open the filter further.

Distortion

Put distortion after the filter. A tube or soft clip style keeps the squelch; harder clipping makes it scream. Our free distorted 303 preset is built this way and is a good one to open and compare.

Programming the pattern

Write 16th notes in one octave with a few notes jumping an octave up. Leave some steps empty, and let a few notes overlap the next one so they slide. Acid lines live around 120 to 135 BPM in acid house and techno.

Five free Serum 2 presets →A house 808, a distorted 303, a French touch lead, a retro pad and a trance pluck. Open them and see how they are built.EDM Serum presets: 71 for Serum 2 →VISIONS OF TOMORROW: basses, leads, pads, plucks, keys, stabs and FX. Requires Serum 2. $29.A techno beat to play it over →Hear the pattern and download it as MIDI.Where to save your Serum 2 preset →The Serum 2 presets folder on Windows and Mac, and how to make new presets show up.

Five free Serum 2 presets

From our VISIONS OF TOMORROW pack: an 808 bass, a distorted 303 acid bass, a French house lead, a retro pad and a trance pluck. The same download has 16 house drums and three guitar loops. Royalty-free.

Your download now, then two short emails: how to use the sounds, and a 25% code for any of the full packs, valid for a week. Unsubscribe any time.

Questions

How do I get the 303 slide in Serum?

Set the voicing to mono, turn on legato and set portamento to around 50 to 80 ms. Notes that overlap will slide.

What filter for an acid bass?

A resonant 24 dB low-pass with a short envelope on the cutoff.

Saw or square for acid?

Both were on the 303. Saw is brighter and more common; square is hollower.

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