Korg prologue – THE 8-/16-voice pro’s synth?

This took a while. 2 years, to be exact. After release of the 4-voice polyphonic minilogue (that stepping stone to a pro’s synth) we would have expected its bigger brother to arrive soon. But Korg set up another test balloon at first: its monologue. A much-respected monophonic analog synth, available in various colors.

The success of both instruments might have asured Korg of being on the right path. And so the super-synth has now finally arrived: the prologue. A professional Japanese polyphonic synthesizer with 4 octaves / 8 analog voices (prologue-8) or, alternatively, 5 octaves / 16 analog voices (prologue-16). Great sounds.


Well … whether a 8-/16-voice analog synthesizer built in 2018 is destined to write synth history or not – who knows. In any case, the prologue has come to occupy a niche in our studio setup. To make it more precise: the instrument’s polyphony is not its unique selling point, but rather its voice architecture. Its quality of sounds.


Trademark: Made In JAPAN

For a long time, “Made In JAPAN” was synonym for highest quality when it came to electronic gear. However, a number of scandals with several Japanese industrial companies have seriously shaken that image in recent years. According to the Made-in-Country Index, Japan ranked 8th in 2017, but was – alongside Canada – the nation most rapidly catching up again.

[See: Article on the most popular indications of origin, from: welt.de/wirtschaft]

Korg and its prologue are high quality. “Made in JAPAN” is – with good reason – an trademark to be emphasized. Solid chassis, extremely solid, high-quality pots, switches and buttons, attractive wooden side panels, internal power supply: Prologue hardware speaks for itself. Big thumbs-up!


Pitchbend / ModWheel might be slightly oddly placed (above the keyboard! Some people like it, some don’t), but they are a significant improvement over minilogue / monologue. Remember that noisy slider with its center spring? Click – click! That annoying mechanical noise (!) each time you moved the slider? What a blessing to have “real” wheels on the prologue. And they are programmable, too …!

The high quality keyboard – tastefully weighted and thus a pleasure to play – is another real improvement over monologue/minilogue. Ok, ok … a Fatar TP8 / S keyboard would have been even better, but let’s not complain: The prologue keyboard feels great.

All in all, Korg prologue hardware fulfills all criteria of a reputable professional synthesizer. “Made in JAPAN” is still a guarantee for high endurance, functionality and uncompromising quality.


But we can’t avoid asking a few small questions:

Why are imprinted potentiometer scalings missing? These “optical rasterizations” (usually 10 levels with fine subdivisions, like on a measuring tape) are a given with most synthesizers / audio devices / technical instruments. Such printed scalings might have given the prologue an even more professional look and would have made sound-programming a tiny bit more effective.

Fingerprints and dust particles show up all too well on the fine metal surfcae, letting the prologue look old before its time. A dust cover is highly recommended! Cleaning the prologue with a microfibre cloth is certainly possible, but requires a lot of energy, since fingerprints are really stubborn and hard to remove from the surface. So visual maintaining of the instrument requires a bit more work than necessary.


Finally, access to the rear side connections is a bit difficult. Although all in/outputs are labeled on the chassis’ upper edge – which is without a doubt very helpful – you simply can’t see the jacks when bending over the prologue. This has to do with the futuristic look of the chassis, stylishly curved inwards.

Sure, lifting the prologue does solve all (visual) problems, but it does not quite make sense to have to raise the synthesizer each time you wanna establish a connection from the prologue to, let’s say, a monotribe or volca beats (sync in <> out).


Let’s be honest: A these problems are no problems. Lack of imprinted scalings, laborious cleaning procedures, slightly difficult rear-side access … who cares! Those are just peanuts compared to the big plusses of the instrument’s high-quality hardware.

After all, considering other companies’ Toys’R’Us-synth-manufacturing-policies, Korg’s effort to build high-quality (pro’s) instruments can’t be rated high enough.

Welcome to the big show

“The prologue is a keyboardist-oriented analog synthesizer featuring the best of
Korg’s expertise.” (prologue user manual, page 3)

The prologue is indeed a professional synthesizer in many ways, not only in terms of hardware, but also in terms of sound architecture and … SOUND!


The prologue features:

  • 8 / 16 analog voices
  • Each voice includes a MULTI ENGINE providing a noise generator, a VPM oscillator, and the possibility to load user programmed oscillators (via SKD)
  • Duo-timbrality with split / layer / crossfade function
  • Various voice modes: polyphonic / monophonic / unison / chord
  • Two digital effect sections with analog (hardware) access
  • Analog compressor (prologue-16 only) for extra bass boost
  • Arpeggiator with various play modes
  • 500 immediately available sounds
  • Comprehensive connections

Let’s start with the last. The connections are clearly divided in two zones. Power supply and control sockets on one side, audio connections – in a respectful distance to the power supply – on the other side.

Excellent: Sync In / Out for quick synchronization of prologue and other gear (Korg instruments, but bascially all trigger-modules, such as analog drum computers, step sequencers, LFOs, etc.). The expression pedal is programmable! And there are two MIDI busses (USB and MIDI IN/OUT, sadly no THRU).

Internal memory commands 500 sounds. That’s definitely more than enough. 250 factory presets and 250 (blank) INIT sounds. The factory presets are brilliant. However, those high-quality presets won’t surprise you after you’ve looked at the list of sound programmers  (User Manual). The 250 factory sounds are from Francis Preve, Henning Verlage, Ian Bradshaw, James Sajeva & Nick Kwas, John Bowen, Kazuto Okawa, Luke Edwards, Tim Mantle and … well … KORG Inc. themselves.

The arpeggiator is very useful, the options speak for themselves. “Manual” mode breaks down the exact order of their input. “Poly Random” creates random patterns with two (!) independent notes. It goes without saying that velocity can be immediately implemented into the Arpeggio line. If you emphasize a single note (more or less), it also appears louder (or softer) in the arpeggio pattern.

Next, the different voice modes, whereby the VOICE DEPTH MODE controller plays a decisive role. This adjusts the way you hear the sub-oscillators and how many there are (monophonic mode), how strong the spread of individual voices is (Unison Mode), and which chords are played (Chord Mode).

Spreading the voices in the stereo panorama is also possible (VOICE SPREAD), which in turn is reminiscent of the magnificent soundscapes of the recently presented Oberheim OB-8. A musically wonderful feature..

And now to the actual core of the prologue – its voice architecture. Let’s start with the oscillators. While the oscillator’s classic part (VCO 1 / VCO 2) does not need much explanation (here, OSC Sync uses ring modulation, cross-modulation, all that the heart desires), the MULTI ENGINE – developed specially for the prologue – is the spectacular essence of this instrument.

Depending on your musical needs, the MULTI ENGINE – nomen est omen – delivers one of 3 sound sources. Noise is still the simplest application. Nothing to be set there. Noise is just noise. Activation, and off you go.

VPM Oscillator: Variable Phase Modulation. This engine is – we quote Korg – built with a carrier and a modulator. Granted, the meaning of this still eludes us. The circuit diagram is something for student technicians! And the description of each oscillator type reads like the directions for a missile system.


The following 16 (VPM) oscillator types are available:

  • Sin1: Modulated sine wave carrier basic type.
  • Sin2: Sine wave carrier and a modulator with self-feedback
  • Sin3: Sine wave carrier with modulator 3 harmonics higher
  • Sin4: Sine wave carrier with modulator 5 harmonics higher
  • Saw1: Modulated sawtooth carrier basic type
  • Saw2: Sine carrier based pseudo-sawtooth type
  • Squ1: Modulated square wave carrier basic type
  • Squ2: Sine carrier based pseudo-square wave type
  • Fat1: Second subharmonic modulator with self-feedback and driven carrier output
  • Fat2: Half subharmonic modulator with self-feedback and driven carrier output
  • Air1: Noise modulated sine wave carrier
  • Air2: Sine wave carrier modulated by both noise and a sine wave
  • Decay1: Type with decaying modulation amount
  • Decay2: Type with strong decaying modulation amount
  • Creep, Throat: Experimental type with complex and evolving modulations

One thing is certain: Some waveforms sound quite ordinary (sinus, etc.), but others are enormously experimental.

Finally, USER (USR) is a completely self-contained oscillator engine that can be loaded into the prologue. Here too, up to 16 (own) oscillator programs – user oscillators – can be accessed. Although the factory version, however, has only a standard user oscillator.

The implementation of “user” oscillators (as well as “user” effects) should be done with the Software Development Kit (SDK), which Korg offers for download on its website. Working with SDK requires a firmware upgrade which is scheduled to come out in July 2018.

The further sound path of the prologue – mixer, filter, amplifier – can be more or less skipped. There is nothing new here.

However, we would have preferred a small adjustment (we’re just dreaming, of course). The arrangement of the envelopes should be – in our opinion – reversed. The top ADSR for the filter, the lower for the AMP. Here it’s the other way around.


The LFO can operate in 3 speed areas (FAST / SLOW / BPM). Simultaneously pressing SHIFT and turning the INT(ensity) knob will invert the selected waveform. This is just one of many examples of how many useful little details the prologue has been provided with. Details also discussed in the excellently user manual.

Finally, the effect section is another special tool to give a finishing touch to the sound as a whole. Thanks to the (analog) operation, adjusting the effects is a question of seconds.


The compressor – only to be found in the big prologue 16, by the way – is not only a nice addition, but an important tool to optimize the sound. This is because the prologue basically sounds in the base range soewhat thin, the emphasize in the middle. At this point, the compressor compensates for what the sound generator has misses. Prologue 8 users will probably have to do this work-step externally to improve the low audio frequencies.

Sound: prologue in action

Granted, thaat’s one boring headline. But the content is the essence, as we say. And here we come to the core of the report, to some very important, fundamental considerations concerning the Korg prologue.


The thing is: 8 analog voices sounds like a pretty decent setup. And 16 analog voices “sounds” even better.

Now, voice and sound are two different things. Only a fool would sell his aged Roland Juno-60 to make place for the prologue 16. Yes, he got rid of awkward MIDI implementations with this sale. But je has lost Juno’s warm, earthy sound as well. Any attempt to replace a polyphonic analog synthesizer from before 1985 with the prologue is doomed to fail.


Warm pads and organic (living) sounds are not the great strengths of a prologue. Its sound character is modern. Diverse and yet rather cool. But if your primary goal is multi-voiced carpeting, then there are more suitable (analog as well as virtual-analog) candidates.

What truly distinguishes the prologue is its enormous sound design potential. And, as a kind of sweetening, considerable polyphonic architecture.

Maybe you’re tired of those eternally same Jupiter 8 string imitations. And of the eternally same Moog basses. CEM 3340 in the 100th version? No, thanks. Something, a little revolutionary? Ye, please.


Sound design is – in our opinion – the core of the prologue. Its most important building blocks are:

  • The MULTI ENGINE: VPM Oscillator / USR Oscillator
  • OSC sync, cross / ring modulation as well as own pitch envelope for VCO 1
  • The rough filter resonance: For the somewhat “different” – not necessarily “beautiful” – filter sweeps
  • (Almost) infinitely long Portamento times (terrific)
  • The PLAY MODES, including stereo sound impressions, detuning options, DUAL / SPLIT and much more
  • The successful EFFECT department
  • Programmable Expression Pedal / ModWheel

These features are the key to a different sound, one that goes – at least to some extend – beyond the typical analog clichés.


Some modest questions

First: The LFO. The challenge lies with the sound-design-task “modulation in the audio area”. LFO frequency up to 2 kHZ sounds good in theory. But the prologue Low Frequency Oscillator fails as soon as it goes into the audio modulazion range. (As with so many modern synthesizers, by the way). Audio file “HighFrequ LFO” illustrates how “digital” the LFO sounds in the audio mod range (adding unexpected digital elements).

Second: The LFO again. It would have been great if prologue had featured at least 3 or 4 of those modules. And speaking of sound-design, that would have made sense …

Third: Dynamics. Like almost all modern (polyphonic) analogue synthesizers, the prologue has no significant dynamic range. Clipping is an inherent aspect of the prologue output signal. Modern analog synthesizers operate in a permanent “mid-dynamic range” (irregardless of the number of voices), whereas vintage analog polysnths yield an increase in volume with an increase in the number of voices.


All in all

The Korg prologue is – notwithstanding small points of criticisms – a professional synthesizer for sound tinkerers and sound enthusiasts, especially for those who recognize the enormous advantage of the instrument’s technical subtleties (MULTI ENGINE, etc.) in combination with its extensive polyphony. All in all: Its musical flexibility. Soundwise, prologue delivers both classic (vintage) analog sounds, and new, unheard modern analog sounds.

In both MONO and UNISON mode, the prologue performs as a first-rate solo synthesizer. With focus on “special” lead sounds, effects, basses, novel sound effects, exciting arpeggio performance, and much more.


In POLY and CHORD mode, the prologue either remains a luxurious solo synthesizer (with complete freedom to sound as long as necessary without individual voices being cut off), or becomes a first-rate orchestral synthesizer. Focus rests here on “special” pad sounds with the finest of tonal nuance, generous filter sweeps, novel waveforms and sync-triggered arpeggios (poly-random!) and chords.

Generally speaking, we recommend the larger of the two prologues. Not just only because of those luxurious 16 voices and that 5 octave keyboard, but also because the programmability has been solved more elegantly in certain points (extra hardware knobs for split / layer …). And then again, the prologue-16 has an integrated compressor (truely analog and thus non programmable) to optimize the overall audio range. Not a bad deal!

Music files: It’s all Korg prologue-8, with Yamaha’s SK-20 Symphonic Ensemble and the monotribe drum station here and there.

Korg prologue-8 / prologue-16

Polyphonic Analog Synthesizer
8 voices / 16 voices

prologue-8: 1,499 Euros / USD
prologue-16: 1,999 Euros / USD

Website Manufacturer:

Korg Prologue-8 photo 1 (1800 x 1000 px)
Korg Prologue-8 photo 2 (2000 x 1200 px)

Filed under 2018, Reviews

“Es genügt, einen Ton schön zu spielen” sagte der Komponist Arvo Pärt im Jahre 2005. Diese Aussage ist ebenso einfach wie ich auch exzellent: Es braucht kein Meer an Tönen, denn entscheidend ist der Klang. Dass so mancher Vintage-Synthesizer der 70er und 80er Jahre teils unerreicht hochwertige Klänge liefert, steht außer Frage. Doch tatsächlich leben wir “heute” in einer nahezu perfekten Zeit. Einerseits hat man – mehr oder weniger – noch Zugriff auf die Vintage Analogen, andererseits wird auch bei Neugeräten die wichtige Komponente des hochwertigen Klanges wieder zunehmend berücksichtigt. Doepfer, Cwejman, Synthesizers.com, MacBeth, Moog, GRP, Studio Electronics, COTK, John Bowen und andere Hersteller bauen hervorragende Synthesizer, die den “Klassikern” in nichts nachstehen. All diesen (alten wie neuen) “großartigen” Instrumenten ist Great Synthesizers gewidmet. _________________________________________________________ In 2005 composer Arvo Pärt said: “Playing one tone really well is enough”. In other words, it is sufficient to play one tone 'beautifully'. I agree with that. All musical efforts are focused on the sound itself. Although I studied classical music (piano and drums), it’s the electronic sound that inspires me. Synthesizers are the epitome of new sounds and exciting tonal spheres. Today, many companies produce high-quality - excellent! - synthesizers: Doepfer, Cwejman, MacBeth, Moog, GRP, Synthesizers.com, COTK, Studio Electronics, John Bowen and others. It's their products I'm really interested in ... apart from Vintage Synthesizers, which I have been collecting for 20 years. Subsequent to our former websites Bluesynths and Blogasys, Peter Mahr and I have now created GreatSynthesizers. We hope you like it.


  1. Hi Theo,

    The VPM oscillator is a declination of the MOD7 oscillator found in the Kronos/Oasys. Not exactly the same (waveshapers are not involved), but this is essentially a VPM oscillator, with only one carrier and one modulator, and no algorithm/patching features.

    I really like what I hear. This is not intended to be another vintage emulation, but a recreation of what 21th century analog sound should be. I found the same philosophy in the Schmidt eight voice synthesizer.

    • Theo Bloderer

      … thanks for the note! I have to study the VPM philosophy a bit, it’s kind of new to me. And you’re absolutely right – the prologue is not just another vintage emulation, but a modern analog synth with a sound of its own … Big compliments to KORG for developing something “new” …

  2. gridsleep

    Good information. Thanks. BTW, “irregardless” is a Yogi Berra-ism.

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