Astrix-Style Square Bass in Serum (Psytrance)
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The Astrix "Universo" bass is a blocky, aggressive square sound, and it is simpler to build than it seems. The character comes from the waveform choice and a hand-drawn LFO on the filter, not from stacking effects inside the synth.
Start minimal, split the sub from the harmonics so it plays clean under the kick, and shape the movement by hand.
Key takeaways
- Square and pulse waves give the aggressive, blocky character. Simple waveform plus filter movement beats complexity.
- Split the wavetable: one oscillator plays only the fundamental (sub), the other plays only the harmonics. Now you tune each separately.
- Mute the sub on the second 16th with an LFO so it never clashes with the kick transient.
- Punch comes from manually drawing the LFO curve on the filter cutoff. Blockier shapes hit harder, smoother curves soften.
- Randomise the wavetable phases to spread the high end across the cycle for a metallic, less clicky tone.
Psytrance production FAQ
How do I start a square bass in Serum?
Keep it minimal. A square or saw oscillator, resonance at zero, phase randomisation off so it starts predictably, and velocity mapped to level. Begin on a lower note for good sub content and leave the upper harmonics to the filter and processing later.
How do I stop the sub clashing with the kick?
Split the oscillators. Copy oscillator A to B, set B to play only the first harmonic (the sub) and A to play only the harmonics with the fundamental removed. Then use an LFO to mute the sub on the second 16th note so the kick transient stays clean. Now you control sub and harmonics independently.
How do I get the blocky, punchy movement?
Use one LFO in envelope mode at around 1/16 or 1/8 triplet on the filter cutoff, and draw the curve by hand. Blockier shapes give a harder sound, smoother curves give a softer one. The punch is in the LFO drawing, not effects inside the synth.
Why use square waves for psytrance bass?
Square and pulse waves sit in a sweet spot: richer than a plain saw, simpler than FM, and their harmonics cut through the mix without sounding thin. Combined with filter movement and the sub/harmonic split, that is what gives the aggressive Astrix character.