Korg opsix mkII 37-Key Altered FM Synthesizer

The Korg opsix mkII is an advanced Altered FM synthesizer designed for deep sound design, modern electronic production, and expressive performance control. It builds on Korg’s original opsix platform by significantly expanding polyphony and refining workflow efficiency while retaining its signature “FM-made-intuitive” architecture. The result is a powerful digital synthesizer capable of everything from classic FM tones to hybrid subtractive, additive, and wave-shaping sound design.

At its core, the opsix mkII uses a unique 6-operator FM synthesis engine that goes beyond traditional FM synthesis. Each operator can function in multiple modes—including FM, ring modulation, filtering, wave folding, and effect generation—allowing users to move seamlessly between classic FM sounds and entirely new synthesis paradigms. This flexibility makes it suitable for both traditional electronic timbres and highly experimental sound design workflows.

The instrument delivers up to 64-voice polyphony, enabling complex layered patches, long evolving pads, and dense sequencing without voice dropouts. A wide selection of oscillator waveforms, filter types, and modulation sources further expands sonic possibilities, making it capable of both precise tonal shaping and aggressive digital textures.

A key feature of the opsix mkII is its highly visual and interactive programming approach. The front panel provides direct access to operator levels, ratios, and modulation routing, allowing users to sculpt FM structures in real time without deep menu navigation. This significantly reduces the complexity typically associated with FM synthesis, making it accessible to both beginners and advanced sound designers.

The onboard motion sequencing system enables parameter automation across multiple lanes, allowing sounds to evolve dynamically over time. Combined with a powerful step sequencer and arpeggiator, the opsix mkII becomes a generative sound engine capable of producing continuously shifting textures and rhythmic modulation patterns.

The effects section includes three independent FX blocks with a wide range of processing types such as chorus, phaser, delay, distortion, reverb, and mastering-style effects. These can be layered and modulated to further extend the sonic depth of each program.

Designed for performance flexibility, the opsix mkII includes real-time control knobs, pitch and modulation wheels, and a clear workflow-oriented interface. It integrates easily into both studio and live environments via USB MIDI and standard MIDI connections, making it suitable for DAW-based production or standalone hardware setups.

Key Features

• 6-operator Altered FM synthesis engine with expanded synthesis modes
• 64-voice polyphony for complex layered sound design
• Multiple operator modes: FM, ring modulation, filter, wave folding, and effects
• 40 FM algorithms plus user-definable algorithm structure
• 23 oscillator waveforms including additive and noise sources
• 11 filter types including MS-20 and Polysix-style models
• 3 LFOs and 3 envelope generators for deep modulation control
• Motion Sequencing system with up to 6 modulation lanes
• Step sequencer with up to 16 steps and multi-note programming
• 3-part effects engine with 30 high-quality effect types

Sound Engine & FM Architecture

The opsix mkII redefines FM synthesis by allowing each operator to function beyond traditional frequency modulation roles. Operators can act as filters, wave folders, or effect processors, enabling hybrid synthesis structures that blend FM, subtractive, and additive techniques within a single patch.

This “Altered FM” approach allows users to build complex harmonic structures without requiring deep mathematical programming knowledge, making FM synthesis more intuitive while significantly expanding creative potential.

Motion Sequencing & Modulation

The motion sequencing system allows real-time recording and automation of up to six parameters simultaneously. These can be looped and edited per step, enabling evolving textures, rhythmic modulation patterns, and dynamic sound movement that evolves over time without external sequencing tools.

Combined with multiple LFOs, envelope generators, and virtual patch routing, the opsix mkII supports extremely deep modulation structures capable of generating complex, evolving soundscapes.

Effects & Sound Processing

The integrated effects engine includes three independent effect blocks with 30 effect types ranging from standard modulation and delay to distortion, compression, and reverb processing. These effects can be combined and modulated within the synthesis structure for fully integrated sound design.

Performance & Workflow

The opsix mkII is designed for hands-on sound shaping, with dedicated controls for operator levels, ratios, and modulation routing. This eliminates the need for deep menu diving and allows immediate interaction with FM synthesis structures in real time.

Its compact keyboard format and performance controls make it suitable for studio production, live electronic performance, and modular hybrid setups where expressive control and deep synthesis are required.

Ideal For

• Sound designers working with FM and hybrid synthesis
• Electronic music producers seeking complex digital textures
• Live performers needing motion-based evolving soundscapes
• Experimental musicians exploring algorithmic synthesis
• Studio users integrating deep modulation workflows into DAWs

The Korg opsix mkII delivers a modern reimagining of FM synthesis, combining deep modulation capabilities, expanded polyphony, and an intuitive control interface to create one of the most flexible digital synthesizers in its class.