A few years ago I joined a local band as keyboard player, and it was there I was introduced to the microKorg. Despite the rather amateurish looking premise of categorizing sounds with a 'genre selection knob' and the baby-sized keys, I found myself constantly inspired while jamming with it, and the sounds it could make when connected to a PA rig were massive in contrast to the microKorg's tiny size.

A couple of months ago I decided I must own one, and ended up with the newer microKorg XL because it was on offer for very little more. In comparison to the classic model, the XL has 8 voices - double the polyphony, a 16-band vocoder (the original was an 8 band - and surprisingly intelligible for it), and a seemingly identical but expanded synth engine. After ordering, however, I found out that despite the similarities in features, the XL's engine is based off of Korg's Radias 'Multi Modelling Technology' (whatever that is), while the original is not.



Thankfully, the sound of the XL is as much a joy to behold as it's forerunner. The overall sound is perhaps a touch cleaner with less 'perfect flaws', but it is also more versatile, and can get just as downright nasty as the worst of them if you ask it to. On offer are several types of waveform - your usual sine, triangle, square and sawtooth, filtered noise, as well as a formant wave for voice-like sounds, 64 sampled and additive/digital waves (including a not too shabby piano, and various samples from other Korg boards) and finally an audio input to turn the XL into an effects processor.

On oscillator 1 of 2, various waveform-bending parameters can be chosen between. For example, variable phase unison for making one voice sound like 5 detuned copies of it's-self or producing waveform variations, cross and variable-phase modulation, and my favourite, 'waveform', which allows you to directly alter the waveform geometry in a certain way for each wave type... Predictably, the square wave becomes a variable pulse for that classic thick/thin pulse-width modulation (PWM) sound. The saw shears it's vertical face into two as you increase the parameter, and one slides over the other, creating a subtler version of PWM and chorus effects. The triangle wave's peak splits into two and doubles up as you increase the parameter, which again produces a mellow phasing, and can make the triangle brighter and more interesting. Finally, the sine wave seems to have some kind of FM (frequency modulation) effect - on an oscilloscope the waveform curls up producing a brighter wave whilst still keeping it's essentially pure quality. The second oscillator forgoes the waveform tricks and offers only the four basic shapes, but adds the option to engage ring-modulation, oscillator sync (where the waveform is reset to the start every time oscillator 1 completes a cycle to create 'tearing' and 'synth guitar' type sounds), or a combination of both which is quite devastating in some situations. Clearly, before you even hit the filter, many waveshapes and tone modulations are possible in the oscillator section. Waveform modulation is not possible on the formant wave, but this has it's own parameters to tweak and modulate.

Now let's examine the filters. That's right, there are two! One is smoothly variable between 4-pole lowpass, 2-pole lowpass, highpass, bandpass and bypass modes, all with sweet, non-digital sounding resonance, while the second filter is limited to pure filter types but can be routed with the first in serial, parallel, or with each oscillator having it's own exclusive filter. Needless to say, things can get pretty sexy... What happens if you modulate one oscillator with another, and then start filtering one (but not the other)? Then start morphing the filter shape and you really feel like you're doing science as opposed to going through the usual 'osc, filter, amp, fx' motions. As a nerdy side note, it isn't documented, but the first filter can also produce a notch and a peaking (resonance only) response, if you dial in the right points in the continuum.

None of this would mean a lick if the sound quality was unpleasant, but I'm pleased to say the first word that comes to mind is 'sweet'. This is no moog ladder filter, for sure, but it has such a musical sound, with resonance which can go into self-oscillation without sounding digital. Even without resonance, the filter sounds interesting (which is one of my acid tests for testing filter sounds), and running external signals through it is a worthwhile exercise and produces better results than most software filters. Since sound is subjective, there's not a whole lot more I can say, but this kind of modelled filter would give a lot of analog filters a run for their money in my opinion.

Of course, both filters can be swept independently, by just about anything. In fact, any parameter is yours to sculpt any way you wish, employing keytracking, the modwheel, knobs on the control surface, midi, etc... There are two LFOs and three envelopes, and in addition to the preset modulation slots which are set up for the most common synthesizer programming duties, there are 6 additional 'virtual patch' slots allowing you to set up complex modulation routings and expressive sounds. It's a shame there's no aftertouch, or maybe a couple of extra knobs, because there are so many possibilities!

In addition to all of this, each patch has it's own distortion/waveshaping settings, a two band sweepable EQ, and two effects processors, which I will cover later. The distortion section has several algorithms to select from and an amount, not to mention an option to patch the distortion before or after the filter, which is very useful for changing the sound of the filter, and/or the patch in general. Drive and distortion, clipping and bit crushing are all available, but also included are less straightforward types. One causes the waveform to wrap vertically on it's-self, allowing you to create exotic morphing and PWM-type effects by carefully varying the input level, and one causes something similar, but with the waveform being mirrored back into it's-self beyond the clipping area (like a triangle wave). These effects are quite complex and I recommend either designing the sound around the distortion and using an oscilloscope to see what you're doing, or using them as subtle flavoring, as they can quickly scramble a waveform into blasts of noise if you're not careful. If none of these effects suit, how about a sub-oscillator? You can choose to have any of the basic waveshapes sound one octave below the base note, raising the oscillator count to three!

It's this attention to detail and options that makes the XL so engaging to program. I'm not going to go into detail about the effects, but the rich options continue in this end of the signal flow. Various types of delay, distortion, EQ, tape simulation, chorus, phasing, ring modulation etc are available, all with the same fine degree of control over the sound. Most of the FX have their own built-in LFO settings, and some, such as the filter and ringmod, also can track the keyboard, allowing you to add a third programmable filter to the proceedings. How much complexity do you want?! The only glaring omission here, and it's a real clanger, is that there's no reverb. None whatsoever. You can blag it with the extensive delay options, but it's not the same.

Rounding things out, patches can employ unison, which is actual unison which eats into the polyphony unlike the simulated oscillator unison mentioned before, and it sounds considerably different (layering both types of unison together is interesting to say the least). Microtuning is thankfully supported with various preset scales and a user scale option, random pitch drift can be introduced for analog emulations, and portamento is correct and present. Detail to these aspects of pitch can really separate the amateur sounds from the pros and bring a patch to life. Patches can be layered - again halving the polyphony, but given that this technique could give you a sound made of 4 to 6 oscillators (or more with oscillator unison), seven-note chords would simply be too huge a sound to be really useful in most situations.

The sound quality is very tasty. Slight parameter stepping can be heard in some extreme situations when using the pitch or mod wheel to control some functions, but the LFO's, knobs and envelopes are almost always flawlessly smooth. Sweeping the pitch across the full frequency spectrum yields a musical tone with no aliasing and distortion, and the PWM is simply lush, and sweeps right into silence and back to a full, hollow square. The only downside to this whole package is the user interface when programming sounds. For performance, things are fine, and the keyboard has been remodelled to aid solo-ing. I find my fingers bouncing off of the keys and myself forgetting that they're toy-sized, and the tactile connection between the keys and the sound of the synth is addictive. The presets are well made and letting various people play the XL and flick through the presets affirms my thoughts that this is a perma-smile instrument. However, sound editing is slightly less natural than performing...

There are four knobs provided for editing, plus a couple of other controls which help out here and there. Three of these can be patched to anything as part of a sound in performance mode, giving arbitrary control over any three synth or FX parameters. In addition to these, basic envelope, filter and vocoder editing works quite well with the four knobs (with the first knob selecting the edit mode), but making sounds from scratch is a slower process involving two or more layers of menus and pages which some may not get on well with. Despite overshooting a certain position on the knob and missing the desired page sometimes, the four knobs and menus are set up as intuitively as they could be, and the orange 8 by 2 character LCD is a competent guide for sonic adventurers wishing to plumb the depths of the XL. With the manual as a handy and well written reference, every parameter can be at your fingertips within a few seconds.

A PC editor is available via USB, but despite having programmed around 30 of my own sounds so far, I haven't felt the need to use it. Personally, I enjoy the sound and tinkering with the XL so much that I will just sit there (where 'there' often means 'in bed') and chip away at the sound. After a while my fingers memorized the layout of the menus and started turning the knobs while I kept my attention on getting the sound I wanted and conducting sonic experiments. In some advanced situations, such as when editing a layered patch, the menu-hopping gets in the way somewhat, and things can start to feel a bit like keyhole surgery... However, some (such as myself) would argue that a slower pace of editing allows you to take in the sound and the potential changes you can make, and sort of 'enjoy the journey' so to speak. To me, this is a pleasant change from the softsynth interface where any parameter can be clicked on in a matter of split seconds and the sound creation process can be over quickly if you know what you want and how to get it. In addition to wishing they had added a couple more knobs and reverb effects, there are only 128 patch locations, and storing your own means writing over the factory presets, which are mostly very high quality, if a tad conservative for my tastes. This seems a bit stingy in this day and age, but of course, it can be remedied partially with midi-dumps to a computer.

Given the detail in which I've described the sonic functionality of this instrument (and to me it feels worthy of being called just that), you'd think I'd covered everything, but I haven't. Clearly, by cutting various corners, Korg have provided something of a synth behemoth inside an unsuspecting case, and for a price that reflects the case more than the tardis-like sound generating guts.

-Alexandra Cornhill