Korg Prologue 8/16 Voice Analog Poly Synth


Here’s a block diagram of the VPM (Variable Phase Modulation) oscillator, one way the Prologue Multi Engine can be run. This of course is run in software – meaning it’s digital.

There is an awful lot here (i am trying to get my mind around it), but it looks to me that this is capable of a wide variety of sound generation. Like for instance notice the drive at the end. The little circles with the X’s in them are valves, where you can adjust levels and amounts. The manual says in addition, “Sixteen oscillator types are available for this VPM oscillator.” Not sure what this really means but that sounds nice. Not sure how difficult this will be to program, if it’s some sort of gnarly thing where you change one parameter a little, and something strange and unexpected happens, or if it’s one of those things where you have an idea, and you can go in and dial just what you thought of.

So beyond the multiple separate User programs there will be a variety of settings for the VPM on the Multi Engine. Should be a very interesting beast.


The manual says above the VPM diagram above, “This engine is a VPM (Variable Phase Modulation) oscillator that was developed especially for this instrument.”

Perhaps that’s just hype. I think VPM is like FM but different.


I owned both Novation Peak and Prophet 12 both were good but not special or aweome so i sold them. I still have the DSI Poly Evolver Keyboard PE Edition and AK ----now these two synths are both awesome and special. DSI Poly Evolver is Dave Smiths finest hour :slight_smile: never to be repeated


I also love the Monologue but a big bonus for it is cost to performance ratio vs other options in the market.

The Prologue, however, on paper at least, I am not convinced.


One question i’m wondering about the Multi Engine, is if all of them have to be doing the same thing or if they can be each set differently and you have up to sixteen different algorithms running simultaneously?


The 16 osc types could be referring to 16 different algorithms?

Yeah, I see quite a bit to love here - feedback, various waveforms for the carrier, proper FM ratios and modulation indexes for making nicely behaving FM, modulator has its own Atk and Dcy… I mean, it doesn’t look like a full-fledged FM implementation but still way more than just switching ”presets”…

My GAS stays… If only Korg would tell us whether or not a desktop version is coming! If not, I’ll have to choose between ”too big” or ”forget about proper layering” :nyan:


Big upset to the Prologue coming on Jan 25 :slight_smile:


I am betting a desktop is likely, they did an 8 and 16 after all, and this looks pretty modular so a desktop shouldn’t be too hard.

It is certainly different from the old Yamaha DX7 kind of FM with the multiple (up to six) oscillators feeding into each other and with a choice of topologies for those oscillators. Plus this VPM has different waves and the Yamaha had only sine waves. And use of the relative phase of the waves didn’t come into play with the DX7 kind of FM. (I think that is what the arrow with ‘phase’ above it means.)

(I still have a Yamaha TX81Z, old but still fun. A hair puller to work with!)


Care to spill the beans?


yeah! I am starting to feel like Korg is deliberately limiting users’ options in this synth, for better or worse. This will be a synth that is fast to work with… Perhaps not too dissimilar to using a DT? (when talking about the philosophy behind the DT as compared to other elektrons, not necessarily the tech itself)


A software developers kit would sure be nice for the Digitakt!


Ahh yes, that would make me buy a DT :diddly:


Noticed something interesting as a front panel difference between the Prologue 8 and the Prologue 16. Besides the addition of the Low Frequency Compressor on the 16 (OFF/ON switch, GAIN knob and VU meter), there is also a complete TIMBRE section on the 16, controls only available in menus on the 8.

Korg Prologue 16 Timbre Section


Excellent reporting, thank you.


Audiofanzine has posted something about it already:

i don’t understand french but I know audiofanzine’s relatively decent reputation, so will certainly be Google translating this.

EDIT: Read up until the point they state ”most internal parameters run at 1024 step resolution”… dayum. the article does seem to verify alot of positives on the beast.

EDIT2: MIDI CC resolution still the old 127-step affair… Some hires NRPN woulda been nice.

EDIT3: One of the audio clips in the article (prologue 1 audio 10 - hybrid) sounds very much like my beloved CZ-5000! Really digging the hybrid sounds of the Prologue. Actually the article states VPM ”Casio CZ” ??

Off topic

Google translate – useful but funny. I translated an article Auf Deutsch once on competitive swimming. In one section after getting it elsewhere correct several times, it translated “the breast-stroke” as “breast feeding”!


As I’m beginning to embrace DX-style sound design on the volca fm, one of the biggest revelations for me is the power of complex envelopes.

I can see that the polylogue envelope section is more weighted toward subtractive music synthesis, but still there may be opportunities to be had that make the lack of LFOs less distressing than first impression.

I used to do analog FM with a Serge Modular. And in a basic way, I can do things like that on the monologue. If I ever went back to the modular world, the envelope section would be given a lot more thought. It’s just as important as having enough mixers, scalers, and VCAs.


Yes, as far as musos are concerned, VPM has been Korg’s way of implementing FM synthesis without violating Yamaha’s patent, at least until Korg released the Volca FM, which playfully emulates the color scheme of the DX7 as well as the sound engine. I read somewhere that VPM is the equivalent of 4-op FM, except the MOD-7 engine in Kronos has a more powerful “6-op” VPM.

Maybe they chose to call the VPM section of the Multi-Engine “VPM” because it’s got a VPM structure rather than Yamaha’s FM.


VPM is just phase modulation and is far from new for Korg or any other company.
Korg have been using it on all their digital synths going back to the Oasys development. Had it on my Z1 back in the day.
I think nearly every Korg digital synth made since has the VPM algorithm onboard.
Sounds very similiar to fm, and is actually what the DX7 uses, rather than true FM


Nope just a few more days to go . No one will be disappointed. It will be something as good if not better than Prologue its a synth, and will be priced between USD$1399 -$1999 somewhere in that range.