Analogue Synthesizers
Reviews : Keyboard
Korg's analogue tribe has two new members, both with little more than pocket‑money prices. Resistance may be futile...
In 2010, Korg caught the world of music technology on the hop with the pocket-sized Monotron. Superficially, it was toy-like, even smaller than a Stylophone, but inside that plastic shell was a heart of analogue, achieved using surface-mount technology and Korg's archive of classic synth designs. It was followed by the Monotribe, whose drums, sequencing and more professional appearance fanned the flames of hope for a continuing upward trend. However, it seems Korg aren't finished with the earlier format yet, as evidenced by the two Monotron models on review today. Timed to ship near to Christmas, might they be the ideal musicians' stocking fillers?
The Monotron Delay and Duo have the same dimensions
(approximately 12cm x 7cm) and the same layout as the original model,
but with an added splash of colour. Each brings something new to the
table, but neither deviates from the brief of being cheap and cheerful.
As before, they are played by a ribbon just 8cm long and have built-in
speakers, a rear-mounted volume control and an auxiliary input for
processing external signals via their much-praised MS10/MS20 low-pass
filter.
Monotrons are highly portable, thanks to two AAA
batteries with a respectable life of around eight hours. It's when you
connect them to your regular sound system (using the stereo headphone
mini-jack) that the depth, quality and appeal of these diminutive
analogues becomes obvious.
Monotron Delay
The Monotron Delay's back panel features a mini-jack headphone output and auxiliary input, a volume control and a screw that adjusts the 'duty ratio' of the LFO's waveform.
I turned first to the Monotron Delay, which outshines its siblings on two fronts, one of them literal: it's labelled in UV-reflective paint. Under black light, the glowing orange text, in particular, should mesmerise geeks, spelunkers and party animals the world over. Its second (and admittedly more practical) new feature is a built-in delay effect that works wonders on the single VCO synthesizer. Korg have long understood the value of onboard effects, especially to the performing musician, and the reasoning is as sound now as it was when I bought my DW8000 keyboard so many years ago.
The Delay's synth is so basic its sawtooth oscillator
has no accessible controls at all — other than the ribbon that smoothly
sweeps its pitch over about six octaves. You should therefore consider
the keyboard markings to be of decorative value only. The Delay's five
knobs set the rate and intensity of the LFO, the time and feedback of
the delay, and the filter cutoff. This is the same low-pass filter found
in all Monotrons, the only difference being that there's no space on
the panel for a resonance knob. The on/off switch also serves as an LFO
waveform selector with two choices: triangle and square. That's it as
far as performance control goes, but there is one final item tucked away
in a recess at the rear. This is a small screw that changes the 'duty
ratio' of the LFO waveform, replicating the old Korg MS trick of varying
the LFO shape continuously. When triangle is selected, a twist of
a screwdriver changes the shape from sawtooth through triangle to
inverse sawtooth, while for the square wave, pulse width is varied. The
LFO provides pitch modulation that extends into the audio range, and as
its rate knob is of clear plastic, you get a visual representation of
the frequency via a green LED on the circuit board below.
At the rear of the Monotron Duo, we find the same headphone and auxiliary input ports as the Delay, but also a red button that is used to cycle through different scales for the ribbon controller.Pitch modulation can be eerie and warbly all by itself, but when engulfed in delay it becomes far more potent. There's no information given about the maximum delay time, but in my recordings it clocked in at just over one second. The delay is clearly digital in nature, something you spot as soon as the feedback reaches maximum and the audio degenerates into a distorted — yet not unpleasant — digital crunchiness. If you adjust delay time during playback the delay mimics analogue behaviour by also changing the pitch, just as a tape-based delay would. This is really rather wonderful from a box so innocent-looking! Turn anti-clockwise towards the shortest delay times and you're into the realm of metallic, reverberant drones tuned by fine adjustments of the time knob.
Happily, you can plug another Monotrons or external
source into the auxiliary input for processing by the delay and then the
filter. In this respect, the owner's manual is incorrect, showing the
filter before the delay in the signal chain when, in fact, it comes
after. The delay output is very noisy, so the routing chosen makes far
better sense anyway. As you close the low-pass filter, it smoothly
removes the excess noise, along with the synth output and any repeating
feedback tones. The feedback control also incorporates delay mix, so
turning the knob clockwise leads to a rush of overdriven delays that, at
the maximum setting, even surpass the source signal. In fact, turned
anywhere after its two o'clock position, feedback rewards you with
dirty, crazy stuff that degenerates rapidly into utter filth. In the few
weeks I've been playing with the Delay it's been my nerdish delight to
reproduce one classic sci-fi sound effect after another.
Monotron Duo
For those who appreciate synthesis of a more tuneful nature, Korg offer the Monotron Duo. Made of blue rather than black plastic, the Duo is closer in design to the original Monotron, the main difference being that instead of an LFO it has a second VCO. This provides the basis for an alternate range of tones generated by VCO cross-modulation — or X-mod. Korg's Mono/Poly is mentioned as the source for this particular treat, but any correlation between the two seems tenuous at best. However, what really sets the Duo apart from the others is the selection of programmed keyboard scales marking it as the 'go to' Monotron for melody.
Both of the Duo's oscillators are square waves with
fixed pulse-widths. There's independent control over their pitch and
their range is reduced slightly compared to the other Monotrons, making
it more controllable for bass and solo duties. By careful adjustment of
the two pitch knobs, you can summon up detunes, musical intervals such
as fifths and octaves, or more abstract, unrecognisable tunings.
I noticed that the oscillators soft-sync quite easily: ie. they can lock
perfectly in pitch. This isn't always a desirable trait, as it
eliminates some of the more subtle analogue 'swimminess'. But here, with
tiny knobs to make adjustments with, it is not unwelcome, and you can
always add instability by introducing a tiny amount of cross modulation.
Once locked, the automatically tuned oscillators remain together even
on initial power-up, giving the impression that they're actually DCOs
rather than VCOs.
Although VCO2 is the nominal modulation source, it is
clearly affected by the pitch of VCO1 also. This can be seen thanks to
an internal LED and VCO2's clear-plastic pitch knob. A switch selects
whether VCO1 or both oscillators pass through the filter to the outside
world. If you select just VCO1, the second oscillator isn't heard
directly and serves as a modulation source only. The effects of
cross-modulation are anything from a slight distortion or harshness
right up into pseudo ring-modulation atonality. The X-mod intensity knob
on its backdrop of custardy yellow therefore becomes a valued
performance control when soloing.
Soloing is something I find challenging on the original
Monotron so I'm glad to see this addressed — within the limitations of
the ribbon, anyway. At the rear, in the place of the Delay's LFO
shape-shifting screw, there's a small red button that selects the
available scales. Keep pressing it and, in round-robin style, the ribbon
is quantised to chromatic, major, minor and continuous scales, with
chromatic mode the default on power-up. With the ribbon's keyboard
a fraction over one octave long, you won't be trotting out Grieg's piano
concerto to impress your mates, but as long as you're comfortable
tuning root notes by ear, this Monotron is definitely playable. Pick
a scale and the ribbon becomes a controllable means of musical input,
especially when played with a pen tip or a stylus. The scales have the
side-effect of negating the Monotron's finger-wiggling vibrato
technique. Fortunately, this is still achievable in continuous mode,
where you can sweep the pitch smoothly from note to note, creating quite
expressive Theremin-type solos.
Common to all Monotrons, the ribbon triggers a simple
on/off envelope that produces an audible click, which is especially
noticeable when the filter is partially closed. This aside, two
oscillators plus a rasping resonant VCF offer bigger solos and stabs
than any pocket synth has a right to. The oscillators' square waves are
distinctly hollow, separating the Duo tonally from both other Monotrons
and, experimenting with cross-mod amounts and tuning, I discovered
drones of a gritty, almost didgeridoo-like quality. The auxiliary input
is once again present, so that external sources can be filtered. This is
ideal for adding resonance to the Delay model, should you own both.
Conclusion
There's something very endearing about the whole Monotron range, and it's hard to imagine the newcomers won't be snapped up in large numbers. For example, within just a few minutes of switching on the Monotron Delay, I had resolved to keep it. I'm a sucker for delay effects generally but, given that this is an inexpensive, battery-powered synth with a freaky, degrading delay built in, I don't think I'll be the only one hooked. The combination of a pitch-sweeping delay and feedback that reduces every source to a rough, noise-like mulch creates a strangely unique and beautiful lo-fi instrument. The Delay is equally useful for processing the other Monotrons, and even though it's the noisiest of the bunch, I didn't personally see this as unpleasant. There's always the low-pass filter to tame the hiss a little, but for cosmic sound effects, think of it as adding atmosphere.
For more conventional performance, the Duo is intended
to slot in. You might have to record in stages if your melodies stretch
beyond an octave, but being able to quantise the ribbon to recognised
scales is the Duo's trump card. Ironically, it might still be the one
that's most overlooked, but it has its own charm, thanks to its filter
and screeching cross-modulation. Of all the Monotrons, it is the one
that improves most dramatically when you switch to full-sized speakers
and external effects.
Being analogue, these new Monotrons will probably be
modified as widely as the original — an option denied to purchasers of
far more expensive virtual analogues, I can't resist pointing out. In
just over a year, Korg have upgraded their status from 'experimentally
dipping a toe back in the analogue pool' to 'number one Japanese
analogue synth manufacturer'. This has a nice ring to it and with that
last thought, I'm going to dare to hope that the next surprise will be
even bigger! .
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