So Acid — Info

01 / Signal Architecture

So Acid is built as a generative performance system rather than a conventional MIDI player. The arrangement generates a continuous acid synth foundation alongside kick, hats, claps, snares and additional percussion. Each track receives its own synthesis and drum fingerprint.

The acid voice uses a main oscillator and a sub oscillator, followed by waveshaping, a low-pass filter and a VCA. The main acid oscillator is sawtooth-based, with the sub providing additional weight.

The important distinction: the acid synth is not simply changing notes on a sequencer. Its 16-step pattern is also used as a modulation performance. Filter, resonance, envelope, decay, accent and slide changes can occur for individual steps while the bass voice remains continuously present.

02 / Frequency Map

These are the approximate synthesis ranges currently defined by the generator. They are useful as a map of where each voice is designed to contribute, not as isolated EQ prescriptions.

Voice	Generator range / target	Role
KICK	44–68 Hz fundamental ~85–190 Hz initial pitch	Sub/low-end impact and the short pitch-drop transient.
ACID SYNTH	Low-frequency foundation; LPF can open to ~5 kHz	Primary tonal voice. Resonance creates the characteristic moving acid peak.
SNARE	~110–230 Hz body target upper noise/snap layers	Body plus noise-based attack. The final spectrum depends on the selected snare family.
CLAP	~750–1,700 Hz tone target	Mid/high rhythmic transient with optional layered and metallic variants.
HATS	~1.5–7.6 kHz filtering range	High-frequency rhythmic texture. Brightness, decay and micro-variation change per track and step.
PERCUSSION	~70 Hz–7 kHz depending on voice	Metal, wood, rim, noise, tom and industrial families occupy different areas.

The kick, hats and percussion are intentionally constrained so that generated variations do not create uncontrolled high-frequency or ultrasonic material.

03 / The Acid Voice

The acid engine maintains a persistent synth state. When a modulation event is present, a parameter receives a new target; otherwise its previous state is carried forward. This is what allows the bassline to feel like one evolving synthesizer performance rather than a collection of unrelated bass notes.

OSCILLATOR Sawtooth primary oscillator plus a sub oscillator. Oscillator octave, level and detune can vary.

FILTER Low-pass filter with substantial resonance and dynamic cutoff movement. Acid filter motion is the main timbral engine.

ENVELOPE Envelope modulation changes how strongly the filter opens on individual articulations.

DECAY Shorter and longer articulations change the perceived bite and sustain of the acid pattern.

ACCENT Accent changes the amplitude and timbral emphasis of selected steps.

SLIDE Generated slides can glide between adjacent notes, with stronger slide behavior on larger intervals.

DRIVE Waveshaping adds harmonic content before the filter, making aggressive filter movement more pronounced.

MODULATION Step-level events can target filter, resonance, envelope, decay, accent and slide behavior.

04 / Drum Vocabulary

The drum generator does not use one universal kick or one universal hat. A track receives a generated drum profile that determines its instrument families, tones, decay behavior and variation.

KICKS Deep · Tight · Boomy · Warehouse · Rounded · Industrial

SNARES Noise · Body · Dry · Long · Metal · Industrial

CLAPS Tight · Wide · Room · Layered · Metallic

HATS Five generated hat profiles with different brightness, decay and noise-layer behavior.

PERCUSSION Metal · Wood · Rim · Noise · Tom · Industrial

MICRO VARIATION Step and bar seeds introduce small timing, decay, brightness and layering changes.

05 / Adaptive Spectral Balance

The generator estimates spectral pressure from the arrangement rather than feeding the master analyser back into the generator. Bass pressure, kick pressure, high-frequency activity and mid activity are used to calculate small complementary EQ movements.

When the low end becomes dominant, the system can gently encourage complementary regions such as high-mid and air content. When the arrangement becomes brighter or denser, those corrections change accordingly.

This is deliberately subtle. It is intended to keep the spectrum from becoming unbalanced, not to make every track mathematically flat.

06 / EQ Architecture

There are two separate EQ concepts. The generator's automatic EQ is allowed to move with the track. The user's master EQ is separate and remains the final user-controlled tonal stage.

Band	Frequency	Purpose
LOW	60 Hz	Kick / sub foundation.
LOW-MID	250 Hz	Weight, body and low-mid buildup.
MID	1 kHz	Core tonal and percussive presence.
HIGH-MID	4 kHz	Attack, definition and rhythmic edge.
AIR	12 kHz	Top-end openness and hat texture.

The generator EQ is limited to small movements, generally within approximately ±3.5 dB. The five user bands are independent controls and are not rewritten by the generator.

07 / Arrangement Engine

Songs are assembled from evolving sections rather than a fixed intro / drop / outro template. The current vocabulary includes OPEN, GROOVE, BUILD, PEAK, BREAK, AFTER, VARIATION and EXIT.

Sections can be 4, 6, 8, 12, 16 or longer bars, with peak sections sometimes extending to 20 bars. Phrase material is evolved from a seed, so later phrases can retain the musical identity of the track while changing their behavior.

08 / Producer's View

Think of So Acid less like a sequencer that is choosing a new bass note every time and more like a performer controlling one acid synthesizer through time.

The notes establish the musical identity. The modulation events establish the performance: opening the filter, increasing resonance, changing envelope depth, shortening decay, adding accents or introducing slides. The drum profiles then provide a separate layer of timbral identity.

The result is intentionally imperfect and dynamic. Repetition is useful for establishing a groove; parameter movement is what keeps that groove alive.

INFO