Hands-on with the Korg Prologue

Oscillators

The Prologue keeps the two analogue oscillators of the Minilogue. These are multi-shape, with square, triangle and saw modes, and each features octave, fine-tune and shape controls, the latter of which modifies the pure waveshapes to add asymmetry and extra harmonics. Once again there are switches for oscillator sync and ring mod.

The big difference here is the addition of a third, digital oscillator, which Korg call a Multi-Engine. This can function as multiple types of sound generator – it can be a noise source with four varieties of atonal noise, and is capable of FM/VPM synthesis, with 16 digital oscillator types offering a range of classic metallic and complex tones. Most interestingly though, it can also be loaded with user-created waveforms. User mode comes pre-loaded with one morphing wavetable oscillator, and features another 16 empty slots ready to be loaded with user creations.

Design and loading of these user oscillators will be handled by an official application. We’ve not seen this ourselves yet, so can’t comment on how it works in action. The possibility of crafting our own oscillators to blend with the Prologue’s analogue innards has us seriously excited though…

Voice modes

There are four voice modes available for the Prologue: poly, mono, unison and chord. A Voice Mode Depth control edits the behaviour of each. In Poly mode, the depth control can put the engine into Duo mode, splitting the synth into two unison voices. In Mono, the control dials in a sub oscillator. For the Unison setting, the depth control dials in detune between the stacked voices. In Chord mode, it’s used to select from a list of preset chord shapes, with the name of each displayed via the oscilloscope screen.

Eagle-eyed synthesists may notice that a couple of voice modes from the Minilogue are missing here. Not making the cut are that synth’s Delay mode, which triggers the synth voices one after another, and sidechain mode, where each new note causes the volume of the previous one to ‘duck’.

Oscilloscope screen

The oscilloscope screen from the Minilogue returns here. When you play a note, this provides an animated visual representation of the waveshape. We imagine this will prove particularly handy when coupled with the new multi-engine oscillator, allowing users to get a good look at what’s going on with the current loaded sound. Once again, this screen doubles up as a patch-browser and settings window. Unfortunately, at least on the build we got our hands on, there’s no hidden mini game included to match the pong-like animation on the Minilogue or the Monologue’s mini platformer. It’s hardly a deal breaker, but we did think it was a nice touch…

Bi-timbral engine

Unlike its smaller sibling, the Prologue is bi-timbral, meaning it can produce two different synth tones at once using its multiple voices. It’s capable of arranging these sounds via splits or layers. There’s a crossfade ability too, allow users to blend between the two sounds.

Filters

The Prologue features a different filter design to the Minilogue. That synth’s multi-mode filter is switched out here for a low-pass with a fixed -12dB slope. Again, there are resonance and envelope depth controls, along with keytrack and filter overdrive switches.

From a sound design perspective, this fixed-mode filter is going to be less flexible than the Minilogue’s multi-function version. However, the Minilogue’s filter can be a little ‘vanilla’ at times, and to our ears the Prologue’s VCF sounds more characterful, particularly coupled with the drive switch.

Digital effects

The DSP-powered effects section uses 32-bit floating-point processing and features two sections: delay/ reverb and modulation effects. Each comes stocked with multiple effects types, the former with standard room and hall reverbs along with longer, shimmering effects, tape-style delay and classic digital verbs. Modulation, meanwhile has plenty of phase, flange and chorus sounds to help bring patches to life.

As with the oscillators section, users will be able to import their own effect programs into the Prologue using Korg’s librarian application. Again, we’ve not seen this in action, so have no idea how easy or flexible this is, but it’s certainly intriguing.

What’s missing?

While the Prologue builds on the template of the Minilogue, there are a few features from that synth that don’t make the cut here. Along with dropping a couple of voice modes and changing the filter, as mentioned above, the Prologue ditches the built-in sequencer of its smaller sibling. Curiously, there’s no audio input here either, which is included on both the Minilogue and Monologue. From our first taste, we’ve been impressed by the sound of the Prologue’s filter and DSP effects, so it’s a bit of a shame not to be able to run external source through these.

...but how does it sound?

Our first impression of the Prologue is that it sounds absolutely fantastic. From what we’ve heard, it can do thick analogue poly sounds very well, with the extra voices, new drive-able filter and modulation effects really adding to the thick, pulsating sound. The inclusion of a digital sound source is a great feature though. Even on its own, the Multi-Engine oscillator is great for those classic ’80s-style glistening bells and sharp-edged synths. As with the similarly hybrid Roland JD-XA, however, it’s the sounds that blend these analogue and digital sources that really stand out.

All that said, our experience with the Prologue is so far mostly limited to the preset sounds created by Korg, and the real test will come when we get to dive in and design some sounds of our own. On initial inspection it seems like the ability to user-upload oscillators and effects is going to be the Prologue’s most exciting USP, so it will be interesting to see how easy and effective this process is.

Two years on, we remain firmly impressed with the Minilogue, so having a bigger, more powerful sibling on the way is definitely welcome. For now count us as tentatively impressed...