Korg Monotron

With arguably one of the finest pedigrees in synthesisers - boasting classics like the MS20 and VC10, Korg are certainly no strangers to analogue technology, and with the huge success of the KAOSS pad series, their recent foray into small compact but very playable devices caused nothing short of a revolution for DJ FX devices. Being an owner of a few Korg pieces in my own studio I was extremely intrigued by the release of one of their latest portable synthesisers.

I must admit, I wasn’t hugely impressed with the Koascillator box, it had some nice sounds inside, but I didn’t see it as much more than a toy that sounded halfway decent, so whilst I was intrigued by the concept of the Monotron, I was also a bit apprehensive about how well it would be implemented - on the one hand it has an analogue oscillator and LFO, plus the filter from the aforementioned MS20 synthesiser, while on the other hand it’s not much bigger and certainly lighter than most smart phones, has just a touch strip and tiny controls for playing it, and has the toy-like built in speaker…

So, could this little box really live up to the sound of the analogue predecessors namedropped throughout its promotion?

Well, after having a quick mess about using the built in speaker alone, I was hooked! Having been a bit sceptical about this feature, it actually makes a lot of sense and makes the Monotron a fun device to use, you don’t need to have a full setup connected up to be able to have fun with it, and to me, this is one of the most important things that’s maybe been lost a bit recently in the world of plugins - the fun factor: grabbing a piece of gear and using it straight away, no messing about configuring or creating control templates, just stick some batteries in and off you go!

But whilst this indeed makes the Monotron a very fun toy to play with, it was time to plug it in to some full range speakers and try to get a bit deeper to fully appreciate the sound it can produce.

Being a very compact device the connections provided are on standard stereo mini-jacks (1/8”). The stereo configuration provides the most straightforward connection to line level DJ mixer inputs, however if you are using the device with a mixing console with mono inputs, it can be connected in this way too following some simple instructions.

Taking a look at the front face of the Monotron from left to right, there is a 3-way toggle switch for turning the device on and off and selecting a modulation destination, along with 5 control knobs for altering the sound and under this there is a 1½ octave touch strip keyboard for “playing”, on the back there is a volume control and a recessed control for altering the range of the touch strip keyboard.

The Monotron has 2 “On” modes set by the toggle switch, in “pitch” the built in LFO will modulate the VCO pitch, and in “cutoff” the LFO will modulate the VCF cutoff, providing 2 different modulation modes - it’s a shame they can’t be used simultaneously, but for a device so compact is no surprise.

Moving through the tiny controls on the Monotron the first is VCO pitch - which unsurprisingly changes the base pitch of the main audio oscillator, which has a nice fat sawtooth waveform, allowing either very low frequency subby sounds to be generated right through to ridiculously high pitched squeals reminiscent of the clangers!

The next 2 controls are for the sawtooth LFO - which as mentioned earlier, will either modulate the VCO pitch or the VCF cutoff.

The first LFO control is the “rate”, which controls the speed of the LFO cycles; usefully a light behind the control pulses to give you an additional visual reference of the speed. The second control “intensity” sets the amount that the LFO will modulate from the original value.

I think it’s fair to say that the filter is the real make or break aspect to any synth, really making the difference between a wimpy, lifeless synth and one with attitude and character. I suppose it’s the reason units like Sherman’s Filter Bank and the MoogerFooger pedals are so successful as standalone devices, and why synths like the TB303 have such a distinctive sound.

With the Monotron’s low pass filter coming directly from the MS20, would it really match up in such a small synthesiser?

The last 2 controls are for filter - the standard “cutoff” and “peak” (or resonance) are present, and act just as would be expected - with low peak settings the filter action is smooth and subtle, and when combined with the LFO can be used to create some kind of release to compensate for the missing amplifier envelope. As would be expected, like it’s granddad the MS20, with extreme peak settings will send the filter into self oscillation, which can be used with amazing results, that completely surpassed my expectations of such a small and inexpensive piece of gear.

The real gem in this little black magic box is the ability to input your own stereo audio signal and process it using the filter and even use the LFO to modulate the filter cutoff too! This is really something no synth head should overlook - having a standalone MS20 low pass filter is the stuff of dreams, and with this feature alone, Korg have really nailed it!

Whilst the built in keyboard won’t allow for any serious playing of notes (even if you change the keyboard range using the recessed control on the back), there is one little hidden feature which really takes it from being a 21st century Theremin and makes it into a tidy little single oscillator mono synth! By unscrewing the shell and looking at the PCB of the Monotron you might notice some writing next to solder connections - those kind chaps at Korg have made sure it’s possible to easily modify the Monotron to accept a CV/Gate input (CV/Gate is the old system used to control analogue devices before MIDI), not only that but they have even labelled the PCB, making the modification pretty straight forward (Full details of the mod can be found here - http://www.dinsync.info/2010/06/how-to-modify-korg-monotron.html). Coupling this with software such as Silent Way (http://www.expertsleepers.com/silentway.html) or any MIDI to CV converter will then allow the use of the Monotron in a standard MIDI setup.

What’s really missing from the Monotron is an amplifier envelope; this would really help to make it even better, as there isn’t really a way to shape the sound’s envelope, which is a bit of a downside. It is possible to use the LFO assigned to the cutoff to create a sort of tail to the sound, but naturally it behaves in a slightly different way to a traditional ADSR envelope, or even just a simple ASR envelope, so it’s not ideal. But, if you can CV/Gate mod the Monotron then this is the only real downside to the device - I would say the touch keyboard isn’t an ideal interface for serious use too, but if you mod it, this becomes moot - and to be honest for the price and size, it’s hardly a surprise that everything could be included, so I wouldn’t really say there is much room for complaint.

Whatever you do, don’t be fooled by its understated appearance, size and price - for much less than £100 for the Monotron and the CV/Gate modification, you can have yourself a punchy little monosynth that has the added benefit of a standalone MS20 low pass filter for you to use on any signal you like!