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Korg Opsix Altered FM Synthesiser

Product #81736 | SKU OPSIX | Korg
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  • True 6-operator FM synthesis, and more
  • Makes FM exploration easier than ever
  • Maximum polyphony: 32 voices
  • Easy-to-use 6-fader operator mixer
  • Full editing with the Data Entry rotary encoders


The Korg Opsix Altered FM Synthesiser is an altered digital FM synthesiser that features a true 6-operator sound generator with a diversity of waveforms and operator modes that goes far beyond the realm of standard FM, making it well suited for sound designers, producers, and musicians. The opsix offers the editing simplicity of analogue synthesis to control the power of the FM engine.

There are six sets of knobs and sliders on the opsix panel, each with two-coloured LEDs, which help you quickly and clearly see the relationships between operators, whose roles change with each algorithm. Make direct changes to the pitch and volume for carriers and to the brightness of the sound or strength of the harmonics for the modulators. These controls give you sonic control over the unpredictability of FM just by subtracting and adding sounds as if you were using a mixer or drawbars.

There are 5 operator modes that expand beyond the traditional FM Sinae waves and include FM, ring modulation, filter, filter FM, and wave folder, as well as a wide range of waveforms. There are also 40 preset algorithms and user algorithms, which provide a combination of different operator roles and connections.

Beyond FM, the opsix provides a wide range of analogue-style modulation controls and filters including three ADSR envelope generators, three LFOs, and 12 virtual patches for a huge range of modulation sources. The 11 filter types include the radical MS-20 low-pass / high-pass filter, to the powerful yet soft Polysix low-pass filter that gives your sound a vintage feel; as well as two- or four-pole low-pass, high-pass, band-pass and band reject filters with resonance.

The opsix includes 30 high-definition effects of which three can be used simultaneously. You'll find stand offerings such as compression, AEQ, chorus, flanger, phaser and stereo delay, as well as distinctive effects like rotary speakers, grain shifters, and shimmering reverb effects that add a new dimensions to already remarkable sounds.

The powerful 16-step polyphonic sequencer allows you to record up to six notes per step, edit the velocity, gate time, and playback timing for each note, allowing you to create long phrases, or make subtle shifts in timing to emulate strums or drum rolls. A motion sequencer lets you record up to six parameters, creating smooth motion changes in sound within a phrase or building rhythms that change dramatically with each step.

Other notable features include randomisation, which provides you with unexpected sonic discoveries at the touch of a button and a spectrum analyser and oscilloscope which provide visual feedback to the distribution of harmonics that are caused by modulation, drawing you into a deep synthesiser vortex. The opsix ships with a 12 VDC power supply and includes a free bundle of music software including Korg's Gadget 2 LE, Module, and M1 LE collection, as well as Reason Studios Reason Lite, and iZotope Ozone Elements mastering software.

Key Features:

  • True six-operator FM synthesis and more
  • FM exploration, easier than ever
  • Full editing with the Data Entry rotary encoders
  • Five operator modes that expand FM synthesis
  • 40 preset algorithms and user algorithms
  • Three EGs, three LFOs and 12 virtual patches offer an extensive range of modulation.
  • Eleven powerful filters, including MS-20 and Polysix
  • Three series of 30 types of high-definition effects
  • Visually satisfying editing with a spectrum analyser and oscilloscope
  • Powerful 16-step polyphonic sequencer
  • Adding unpredictability to sounds with the Randomise feature
  • Favourite and smooth sound transition (SST) functions
  • Compact design featuring a 37-key keyboard
Software Bundle
Apps for iPad/iPhone:
  • KORG Gadget 2 Le (music production studio DAW app)
  • KORG Module (piano/keyboard sound module app)
Software for Mac/Windows:
  • KORG Collection - M1 Le (synthesiser sound module)
  • UVI Digital Synsations (synthesiser sound module)
  • AAS Ultra Analogue Session (synthesiser sound module)
  • AAS Strum Session (acoustic guitar sound module)
  • AAS Lounge Lizard Session (electric piano sound module)
  • Reason Studios Reason Lite (DAW music production software)
  • Skoove free 3 month trial of Skoove Premium (online piano lessons)
  • KORG Gadget 2 Le for Mac (DAW music production software)
  • iZotope Ozone Elements (audio mastering plug-in software)


Keyboard 37 Keys (Velocity and Release-Velocity Sensitive)
Sound Generation Altered FM Sound Generator
Polyphony 32 Voices (or Maximum of 24 Voices, Depending on Settings)
Structure 6 Operators
11 Filters
3 Envelope Generators
3 LFOs,
3 Effect Engines,
Step Sequencer
Algorithm 40 Presets + User Algorithm (Unique to Each Programme)
Operators 5 Modes: FM, Ring Mod., Filter, Filter FM, and Wave Folder
Oscillators 21 Waveforms: Sinae, Sinae 12-Bit, Sinae 8-Bit, Triangle, Saw, Saw HD, Square, Square HD, Additive Saw3, Additive Sqr3, Additive Tri3, Additive 12345, Additive 1+2, Additive 1+3, Additive 1+4, Additive 1+5, Additive 1+6, Additive 1+7, Additive 1+8, Noise S/H, Noise White
Filters 11 Types: LPF 12, LPF 24, LPF MS-20, LPF POLY6, HPF 12, HPF 24, HPF MS-20, BPF 6, BPF 12, BRF 6, BRF 12
Envelope Generators 3 x ADSR
LFO 23 Waveforms: Triangle, Saw Down, Saw Up, Square, Sinae, Sample&Hold, Guitar, Exp. Triangle, Exp. Saw Down, Exp. Saw Up, Step4 Triangle, Step6 Triangle, Step4 Saw Down, Step6 Saw Down, StepRnd:Time, StepRnd: Lvl & Time, StepRnd:Level, Random:Time, Random: Lvl & Time, Triangle+, Saw Down+, Saw Up+, Square +
Virtual Patch 12 Routings
Effects 30 Types: Chorus, Unison Ensemble, Phaser, Phaser (BPM), Auto Pan, Auto Pan (BPM), Flanger, Flanger (BPM), Rotary Speaker, Auto Wah, Exciter, Enhancer, LFO Filter, 3-Band AEQ, Distortion, Guitar Amp, Decimator, Grain Shifter, Master Limiter, Compressor, Delay, Delay (BPM), Autopan Dly, Autopan Dly (BPM), Tape Echo, Tape Echo (BPM), Early Reflection, Reverb, Shimmer Reverb, Spring Reverb
Sequencer / Arpeggiator Sequencer: Step Sequencer (Up to 16 Steps, Up to 6 Notes per Step), Motion Sequencer (Up to 6 Lanes)
Arpeggiator: 7 Patterns (Manual, Up, Down, Alt1, Alt2, Random, Trigger)
Programmes 500 (250 Preset Programmes and 250 User Programmes as the Factory-Set Default)
Favourite: 64 (16 Slots × 4 Banks)
Controllers Modulation Wheel, Pitch Wheel, Ratio OP 1-6 Knobs, Level OP 1-6 Sliders, Data Entry A-F Knobs
Inputs/Outputs Headphone: 1/4" / 6.35 mm Stereo
Output (L/Mono and R): 2 x Impedance-Balanced 1/4" / 6.35 mm TRS
Damper: 1/4" / 6.35 mm (Half-Damper Not Supported)
MIDI In and Out: 2 x 5-Pin DIN
USB Type-B Port
Power Power Supply: AC Adapter (12 VDC)
Power Consumption: 5 W
Dimensions (W x D x H) 22.2 x 13.3 x 3.6" / 56.5 x 33.8 x 9.2 cm
Weight 6.9 lb / 2.9 kg

In The Box

  • Korg Opsix Altered FM Synthesizer
  • Power Adapter
  • Software Bundle


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  • Alex
    I wanted a replacement (and hopefully something extra) for my old Yamaha DX FM synth. Korg haven't disappointed. Youtube demos give an odd picture of Opsix in that it doesn't quite get some of the Yamaha FM character - I haven't seen reviews that get the Solid Bass type preset which is a classic. But when you actually get your hands on the Opsix - it definitely does do full-on 80s style FM. All of the cheesy organs, e-pianos, bells, clangs and incredibly solid basses are there and very easy to do. But then Korg have taken it so much further. FIRSTLY - there are way more algorithms, you can make your own algorithms up, more types of operators - you can even use FX as operators and modulators (which can give you very good Physical Modelling type sounds of hammered or plucked strings etc). You have to upgrade to v2.0 OS for that - which is relatively easy to do. SECONDLY - the actual programming and tweaking is far easier than on any DX synth. The operator tuning and levels are the main knobs and sliders so you can fiddle on the fly, which you just couldn't do on Yamaha DX synths. And it's incredibly easy to go from original sound to sonic mangling. It screams like a b@st@rd when you push it, or you can do quite subtle but musical changes THIRDLY - Korg have squeezed in a whole load of great extras. The FX (on all the latest Korg synths) are superb and highly modifiable with LFOs etc on so many parameters. The sequencer is a huge addition - not only for note sequences but you can also use it for modifying the sound to make quite complex evolving textures. If you demo an Opsix - press the sequencer key - all of the presets have some kind of sequence connected and they show it off well. And you can play the sequencer on a per-note basis. i.e. you play the whole sequence from start in whatever pitch you press on the keys. If only all sequencers did this! It's another way of getting simple things like arpeggios, but it's so much more. FOURTHLY - it's capable of so much more than classic FM. Lush fluid sounds, ethereal pads, even rhythmic techno type stuff. It's main character is firmly digital and that's the strength (I already use quite a lot of analogue synths so I wanted Opsix to be a very digital sound, and it is). TBH you'd struggle to get some of its harsh high sounds on analogues - they generally don't do that. The high frequencies can be huge and powerful. It does everything you ever wanted a Yamaha FM synth to do and more. Korg call it "altered FM" and it really is - takes FM into whole new territories. I originally bought it as a DX replacement but it may as well be a whole new synthesis type on top of that. Not a full keyboard - doesn't bother me though. It receives full midi controllers and who doesn't have some kind of midi controller nowadays - no aftertouch on the keys but it does respond over midi. For me it sits nicely alongside my analogues and it makes sounds none of the analogues can do. It would also be a perfectly good main synth if you're starting out. TBH Korg are doing great things lately - I bought a Wavestate then this, and they both really stand out as quite unique and characterful synths.
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  • Product: Korg Opsix Altered FM Synthesiser
  • Manufacturer: Korg
  • Model: OP-SIX
  • RM Product #: 81736

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