PX1

Two independent 6 operator FM engines with that classic 80s digital sound.

Macros – the big tone shapers

These five knobs affect both engines at the same time:

• Brightness – turns the overall sound brighter or darker by adjusting how loud the operators are.
• Touch – controls how strongly the keyboard velocity affects the sound. Higher values = more expressive playing.
• Attack – makes the notes start faster or slower.
• Decay – how quickly the sound changes after the attack, while you hold the key.
• Spread – moves the two engines apart in the stereo field. Great for wide, lush sounds. Use it after copying one engine to the other and making small changes.

Engine Chooser

The switch selects which engine you're editing. All parameters (operators, algorithm, LFO, etc.) belong to the selected engine.

Copy / Paste – quick engine duplication

Copy stores everything from the current engine into memory.
Paste loads that memory into whichever engine the Engine Chooser is currently set to.

A typical stereo trick: set up Engine 1 → Copy → switch to Engine 2 → Paste → change just a few things (for example detune or fine pitch) → turn up Spread.

You can also layer patches: load a patch from the patch browser (goes to Engine 1) → Copy → load another patch (also to Engine 1) → switch to Engine 2 → Paste. Now Engine 1 and Engine 2 have different patches.

Random – explore classic FM sounds

Fills the current engine with a random sound from the classic FM sound palette. Great for discovering new ideas or breaking out of a creative block. Press it multiple times to keep exploring until you find a sound you like.

Engine 2 On/Off

Simple switch that turns the second voice on or off.

Reverb

Built-in reverb with four controls:

• On/Off – turns reverb on or off.
• Size – how big the space feels.
• Damp – how much the high frequencies are softened.
• Amount – how wet or dry the sound is.

Global controls

• Volume – overall loudness of the synth.
• Bend Range – how far the pitch bend wheel moves the sound.
• Transpose – shifts the whole instrument up or down in pitch.
• Mono / Legato – makes the synth play one note at a time, with or without smooth gliding between notes.
• Portamento – controls how slowly the pitch glides in mono mode.

Operators – the heart of the sound

Each engine has six operators. Think of them as six sound sources that can either produce tone or shape other operators.

This is FM Synthesis (Frequency Modulation). A modulator changes the frequency of the operator it's connected to using its own frequency – think of it as an extremely fast vibrato that creates new harmonics instead of a wobble. Carriers are the operators you actually hear. When the frequency ratio between a modulator and its carrier is an integer (1:1, 2:1, 3:1…) the result is harmonic and musical; non-integer ratios produce inharmonic, bell-like or metallic tones. The algorithm decides which operators are carriers and which are modulators.

• Freq Mode + Coarse + Fine – set the pitch of the operator (ratio or fixed frequency).
• Detune – slightly sharp or flat the operator for movement and thickness.
• Output Level – how loud this operator contributes to the final sound.
• Key Vel Sens – how much velocity affects this operator's level.
• LFO AMS – how much the LFO can wobble the volume of this operator.
• Pan – left/right placement of this operator (PX1 extension).
• EG (envelope) – the four rates and levels that shape how the operator's volume changes over time.
• KRS / KLS – keyboard scaling that makes the sound brighter or softer depending on which key you play.

Envelopes – R1–R4 and L1–L4

Each operator has an envelope with four segments. When you press a key, the envelope moves through these stages:

• R1, L1 – Attack: how fast the sound reaches its first peak.
• R2, L2 – First decay: slides down to the second level.
• R3, L3 – Sustain: stays at this level while you hold the key.
• R4, L4 – Release: how fast the sound fades away after you release the key.

The four Rates (R1–R4) control how fast each transition happens. The four Levels (L1–L4) control the volume at each stage. For example, raising L3 makes the sustain level higher; increasing R4 makes the release slower.

OP Key Sync

When enabled, all operator sine waves restart from zero every time you press a key – giving a consistent attack. When disabled, operators start at random positions in their cycle, which adds subtle variation to each note. This is especially useful with two engines: turn sync off on one engine and you get a natural stereo widening effect because the two engines never start in phase.

Algorithm

Chooses how the six operators are connected to each other. Different algorithms give very different tones – from bright bells to warm pads.

LFO – movement and modulation

• Waveform – shape of the movement (triangle, saw, square, random).
• Speed – how fast it moves.
• Delay – how long it waits before starting after you press a key.
• PMD – how much it wobbles the pitch.
• AMD – how much it wobbles the volume.
• Sync – restarts the LFO every time you press a key.
• Poly – gives each note its own independent LFO.

All the original parameter names and behaviours are kept so experienced users feel at home, while the plain-language descriptions above make it easy for anyone to understand what each knob does.