4OSC Synth

The 4OSC Synth is a four-oscillator subtractive synthesizer provided by the Tracktion Engine. It offers a full synthesis signal path with oscillators, filters, envelopes, LFOs, effects, and an internal modulation matrix.

Overview

The 4OSC interface is organized into six tabs:

Tab	Content
OSC	Four oscillators with wave shape, tuning, level, pulse width, detune, spread, pan, and unison voices
Filter	Multimode filter with cutoff, resonance, key tracking, velocity, and a dedicated filter envelope
Amp	Amplitude envelope (ADSR) with velocity sensitivity and analog mode
Mod Env	Two modulation envelopes with ADSR controls and mod destination assignments
LFO	Two LFOs with wave shape, rate, depth, tempo sync, and mod destination assignments
FX	Built-in distortion, reverb, delay, and chorus effects

OSC Tab

Each of the four oscillators has:

Parameter	Description
Wave Shape	Sine, triangle, square, sawtooth, pulse, noise
Tune	Coarse tuning in semitones
Fine	Fine tuning in cents
Level	Oscillator volume in dB
Pulse Width	Pulse width for pulse/square waves
Detune	Unison detune amount
Spread	Stereo spread of unison voices
Pan	Stereo position
Voices	Number of unison voices

Below the oscillators are global controls:

Parameter	Description
Mode	Mono, Legato, or Poly voice mode
Voices	Maximum polyphony (poly mode)
Legato	Legato glide time
Master Level	Master output level in dB

Filter Tab

A multimode filter with its own envelope:

• Type — Low-pass, high-pass, band-pass, notch
• Slope — 12 dB or 24 dB per octave
• Freq — Cutoff frequency
• Resonance — Filter resonance
• Key Track — How much the cutoff follows the note pitch
• Velocity — How much velocity affects the cutoff
• Amount — Filter envelope depth

The filter envelope has independent Attack, Decay, Sustain, and Release controls.

Amp Tab

The amplitude envelope shapes the volume of each note:

• Attack, Decay, Sustain, Release — Standard ADSR
• Velocity — How much velocity affects the volume
• Analog — Adds subtle per-voice variation for an analog feel

Mod Env Tab

Two modulation envelopes (Env 1 and Env 2) that can be routed to any synth parameter via the internal mod matrix. Each has Attack, Decay, Sustain, and Release controls.

Assigning Mod Envelope Destinations

Below the envelope controls, use the + Env 1 and + Env 2 buttons to assign a modulation destination:

1. Click + Env 1 (or + Env 2)
2. Select the destination parameter from the dropdown
3. Click Add
4. Drag the depth slider to set the modulation amount (-100% to +100%)
5. Click X to remove an assignment

LFO Tab

Two LFOs with independent controls:

Parameter	Description
Wave	Sine, triangle, square, sawtooth, sample & hold, noise
Rate	LFO speed
Depth	LFO intensity
Sync	Lock rate to project tempo

Assigning LFO Destinations

Below the LFO controls, use the + LFO 1 and + LFO 2 buttons to assign modulation destinations. The workflow is the same as for mod envelopes:

1. Click + LFO 1 (or + LFO 2)
2. Select the destination parameter from the dropdown
3. Click Add
4. Drag the depth slider to set the modulation amount (-100% to +100%)
5. Click X to remove an assignment

Each assignment appears as a row showing the source and destination (e.g. "LFO 1 > Filter Freq") with a depth slider.

FX Tab

Built-in effects that can be toggled on or off independently:

Effect	Parameters
Distortion	Amount
Reverb	Size, Damping, Width, Mix
Delay	Feedback, Crossfeed, Mix
Chorus	Speed, Depth, Width, Mix

Internal Modulation vs Track Modulators

The 4OSC's internal mod matrix (LFO and Mod Env assignments) operates inside the synth's audio processing. This is separate from MAGDA's track-level modulators, which are external LFOs and curves that can target any device parameter on the track.

Both systems can be used simultaneously — for example, you might use the 4OSC's internal LFO 1 for filter wobble while using a track-level LFO for panning.

AI Sound Design (/design)

The AI Assistant panel includes a /design slash command that generates a 4OSC preset from a natural-language description. Focus a 4OSC device, type /design <description> in the chat, and the assistant fills in the wave shapes, filter type, voice mode, FX gates, ADSR envelopes, and parameter values directly on the device.

The result is a starting point — the AI is consistent within musical genres but won't replace tweaking by ear. Once you're happy, click the device header's save button. The dialog auto-fills the preset name and category the AI chose, so saving is just two clicks.

Quick usage

Run /design --help in the AI chat for an in-app cheat sheet with example prompts.

Design Recipes

These prompts are tuned for the AI agent's vocabulary. They produce reliable results — adjust the wording slightly to nudge the sound in different directions.

Bass

Prompt	Result
/design deep sub bass	Pure sine sub with snappy envelope, mono voicing
/design fat reese bass with movement	Detuned saws + slow filter / LFO movement
/design acid bass with resonant filter	Square + saw with resonant low-pass, mono with envelope mod
/design 808-style bass with sub and click	Sine sub plus short attack click, decay envelope
/design dub-style bass with delay	Filtered saw, mono voicing, delay FX gate on

Lead

Prompt	Result
/design fat detuned saw lead with octave layer	Two detuned saws + octave-up square, legato voicing
/design trance supersaw lead	Multiple detuned saws, wide stereo, polyphonic
/design bright square lead with chorus	Square wave with PWM, chorus FX engaged
/design legato mono synth lead with portamento	Mono legato voicing with legato parameter set
/design screaming acid lead	Saw + square, high resonance, distortion gate on

Pad

Prompt	Result
/design warm analog pad	Detuned saws, slow attack/release, gentle filter envelope
/design evolving ambient pad with slow filter	Long ADSR, LFO on filter cutoff, reverb gate on
/design string ensemble pad	Multiple saws with detune, slow attack, polyphonic
/design dark cinematic drone	Long release, low filter, reverb gate on
/design lush chord pad	Polyphonic, chorus gate on, medium attack

Pluck

Prompt	Result
/design snappy saw pluck	Saw with zero attack, short decay, low sustain
/design muted soft pluck for arpeggios	Triangle/sine with rolled-off filter, short envelope
/design FM-style bell pluck	Sine + sine with detune, short envelope

Keys / Other

Prompt	Result
/design electric piano with chorus	Sine fundamentals, chorus gate on, medium decay
/design rising white noise sweep	Noise oscillator, filter envelope sweeping up
/design impact hit with reverb tail	Short snap with reverb gate engaged

Tips

• Focus the device first. /design writes to whichever 4OSC device is selected. Without a focused device the chat shows the preset only.
• Use a single sentence. "Aggressive distorted reese bass with movement" works better than a multi-sentence brief.
• Mention specific FX. Saying "with reverb" / "with delay" / "with chorus" / "with distortion" engages the matching FX gate. Without these words the FX blocks stay bypassed even if their values are set.
• Mention voicing. "Mono lead", "legato bass", "polyphonic pad" — the AI honours these.
• Mention root. Octaves, fifths, and thirds work; the AI keeps at least one oscillator at the root unless you ask for a chord stack.
• Iterate. If a result is too dark, run /design <same prompt> brighter. The AI re-rolls from scratch each time, but the prompt vocabulary is consistent enough that small wording changes nudge the sound in predictable directions.
• Save with category. The save dialog has a Category field; the AI fills it (e.g. Bass / Deep Sub) so your bank stays organised.