Acid sound design

Acid Lead in Serum 2 for Psytrance

Watch the full breakdown

Acid is one of the most useful sounds in the psytrance toolbox, and Serum 2 makes it easy once you know the routing. It is a saw through a resonant low-pass filter, with an envelope driving the cutoff so the filter squelches on every note.

In the video Psiger builds an acid lead in Serum 2 from the ground up. Here are the stages that matter.

Key takeaways
  • An acid lead is a saw through a resonant low-pass filter. Push the resonance so it rings.
  • Route an envelope to the cutoff so the filter snaps open on each note. That is the squelch.
  • Keep the filter envelope separate from the amp envelope for independent control.
  • A fast filter envelope gives a plucky acid, a slower one gives a longer sweep.
  • Glide and accents add bounce; distortion, delay and reverb add grit and space.

Saw into a resonant filter

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Saw into a resonant filter — screenshot from the video

Start with a saw wave and route it into a low-pass filter with the resonance pushed up so it rings. That resonant filter is where the acid character lives; the oscillator is just fuel.

High resonance is non-negotiable here. Without it there is no squelch.

Envelope on the cutoff

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Route an envelope to the filter cutoff so the filter snaps open at the start of each note and closes again. A fast envelope gives a tight, plucky acid; a slower one gives a longer sweep. This per-note movement is the acid squelch.

Keep this envelope separate from the amp envelope so you control the filter movement independently.

Glide, accents and effects

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Glide, accents and effects — screenshot from the video

Add glide so notes slide into each other, accent certain notes so the filter opens further on them, and finish with distortion, delay and reverb. Glide and accents give the line its bounce and movement, and the effects give it space and grit.

These finishing touches are what separate a lively acid lead from a flat one.

Common questions

Psytrance production FAQ

How do I make an acid lead in Serum 2?

Route a saw wave into a low-pass filter with high resonance, then drive the filter cutoff with an envelope so it snaps open on each note and closes again. That per-note filter movement is the acid squelch. Add glide and accents for bounce, and finish with distortion, delay and reverb for grit and space.

Should I use the amp envelope or a separate envelope for the acid filter?

A separate envelope. The amp envelope shapes volume, but the acid squelch comes from a dedicated envelope routed to the filter cutoff. Keeping them separate lets you control how fast the filter opens and closes independently of how loud the note is, which is essential for getting the plucky acid character.

What makes an acid line bounce instead of sounding flat?

Glide and accents. Glide slides notes into each other for a liquid movement, and accents open the filter further on chosen notes so the line jumps and talks. Without accents the filter opens the same amount every note and the line sounds static. Deliberate accenting is what gives an acid line its groove.