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Alesis Micron

Modelled Analogue Synthesizer By Paul Nagle
Published January 2005

Alesis MicronPhoto: Mike Cameron

Less really is more — the 'smaller' name suggests a cut-down follow-up to 2003's Ion synth, but in fact the Micron includes most of the spec of its predecessor, and has added effects and a built-in sequencer too.

At the end of my 2003 review of Alesis's Ion, I said that if a rack version of this synth were to appear, I would find it hard to resist. However when Alesis forged ahead in their chosen direction, it was to re-cast the Ion not as a rack unit, but as a second, even smaller keyboard: the Micron.

In the trimming process, most of the Ion's expensive, high-resolution knobs have been lost, and its graphical screen has been replaced by a workmanlike two-line job. But that isn't the whole story. The Micron features a dedicated effects chip offering reverb and delay, plus a highly versatile multitimbral mode, a built-in sequencer and a rhythm programmer. These gains add up to an instrument with a unique personality. It would be wrong to dismiss the Micron as merely a budget Ion.

Size Surprise

On unpacking the Micron, you are immediately struck by its size. Shaped rather like a packet of chewing gum, this thing is really small. In fact, if you are habitually saved from gear-buying frenzy due to lack of space, I'll just innocently mention that its dimensions are approximately 58 x 20 x 7cm.

The Micron possesses the full synthesis power of the Ion (and is compatible with Ion patches), so I suggest now is a perfect time for a refresher courtesy of that Ion review (see SOS September 2003). Alternatively, check out the 'Micron Sound Engine' box later). If you're now suitably awed, we'll take the obligatory tour around the Micron's flat red/silver exterior. I'm pleased to report that the Ion's twin audio inputs have survived intact, although the audio outputs have (understandably) been reduced to a single stereo pair. Alongside the three MIDI ports are inputs for a sustain pedal and an assignable expression pedal. A headphone socket and the connector for the inevitable external power supply complete the tidy rear panel.

The Micron's three-octave keyboard feels light and springy, offering velocity and release velocity action, but sadly no aftertouch. Performance controls are limited to three assignable 360-degree knobs (labelled x, y, and z), a horizontal pitch-bender (complete with glowing backlighting) and two horizontal assignable sliders, labelled m1 and m2. The sideways action of the wheel and sliders takes a little getting used to, but I did warm to them, and they feel durable enough to withstand plenty of wiggling.

The opaque plastic Control knob is the Micron's focal point. Around it is a ring of tiny buttons that represent the five available modes. These are Programs, Setups, Config, Rhythms and Patterns. When selected, the buttons light up green, the colour changing to red when you enter Edit mode. Since the Config button is only used to edit various global settings, it is always red when selected.

You push the Control knob to enter Edit mode, initiate actions or to navigate to editable fields. Turning the knob can, according to mode, select patches, scroll through edit pages or perform value updates. In use — and you're going to use this knob constantly — it has a slight 'give' and its notched operation is ideal for fine value adjustments. My only misgiving was that in certain edit screens, it took way too long to increment values to their extremes. For example, adjusting a modulation matrix amount from 0 percent right up to 100 percent took more than 40 full spins, by which time I'd almost forgotten why I was doing it! You'll be glad to hear Alesis have promised to investigate a means of speeding things up for a future OS revision...

Generally, operation is made bearable thanks to a succession of shortcuts — and in probably the most useful of these, the keyboard itself is drafted in. Printed above the white keys are a series of red text labels, 12 of which serve to select program categories with a further 10 designed to drop you neatly into specific edit pages. It works like this: hold the Programs button plus one of the upper keys — let's say the top 'G' on the keyboard — and right away you're editing the envelope section. Choose the top 'A' instead to edit the LFOs, and so on. Repeatedly pressing the same note jumps quickly through the separate envelopes, LFOs, and so on.

Program selection using the shortcut technique is equally nifty. To select a program in (for example) the brass category, hold the Programs button and the lowest 'B' on the keyboard. Precise selection of all things brassy is then achieved by turning the Control knob. The keyboard is also employed in a number of other ways, for example when naming patches.

With just three assignable knobs on offer, they are going to be used extensively too. Fortunately, the assignment process is really simple: when in the Edit screen of a parameter you wish to assign, push down the Control knob whilst simultaneously turning the x, y or z knobs. That's it! You'll notice that not all parameters can be assigned; in particular, effects settings, such as phaser speed or delay feedback, are excluded. Once assigned, parameter values are transmitted as MIDI NRPNs (Non-Registered Parameter Numbers — see the Ion review for a full explanation) and when you touch any of the knobs (although not the sliders), a program edit is recognised and the Store button lights up. Edits remain even after selecting another program, until you begin a new edit.

The user interface is rounded off with seven additional buttons to the left of the display. Of these, Octave (select, with plus and minus buttons) Tap (tempo) and Store are easily understood. Latch does exactly what you'd expect, too — it simulates the holding of notes and is ideal for drones or for the permanent looping of arpeggios and bleepy patterns.

At this point, I must ask Ion owners not to be jealous, because as I move to describe the final two buttons — Phrase and Accomp — the moment has arrived to explore the Micron's secret identity.

Micro Groover

Even with the subtle clues on the panel, you'd hardly expect to find a groovebox without a plethora of dedicated knobs, buttons and flashing lights, would you? Nevertheless, a scroll through some of the factory Setups (the Alesis term for multitimbral arrangements) suggests this is exactly the territory that the Micron occupies. You see, as well as an arpeggiator, the Micron features a built-in sequencer and rhythm programmer.

As an introduction to pattern creation, the aforementioned Phrase button offers a fast and intuitive means to record musical phrases on the keyboard. Simply hold it down and as soon as you start playing, your notes — including chords — are captured (up to a limit of four bars). If you use the m1 and m2 sliders or the pitch wheel, these movements too are recorded (although curiously, not those of the x, y or z knobs). To finish recording, you simply hit the button again. Now whenever you hit the button, your phrase loops can be transposed via the keyboard.

Alesis MicronPhoto: Mike Cameron

Should you wish to explore this feature further (and I'd be disappointed if you didn't), hitting the Patterns button lists all stored patterns including your newly created phrase (helpfully allocated the name '* Phrase'). At this point, a push of the Control knob allows you to select and then edit any of the several hundred factory patterns, alter their length, tweak individual notes, and so on. Each pattern contains a pointer to an associated patch so that when you create new patterns, these can be paired with the most appropriate sounds.

Pattern lengths range from a quarter of a bar to four bars and are optimised for 4/4 signatures. The pattern grid may be non-destructively changed from unquantised to quantised intervals ranging from eight steps per bar to 32 steps per bar with some quirky, shuffle-type intervals along the way. Although the selection of intervals isn't extensive, there is enough flexibility for most purposes. You can switch freely between arpeggiator and sequencer modes too, with the added bonus that any continuous controllers recorded are still transmitted in the new mode. Sadly there's no way to send only the controllers (without accompanying notes) but otherwise, the sequencer is hard to fault. Even with the two-line display, editing individual steps, deleting data and even dragging and dropping notes (or whole chords) is possible.

Rhythms are an alternative way to create (non-transposable) looping patterns consisting of up to 10 drums, referred to as A-J. Drums are selected using the rhythm button in conjunction with the keyboard. Each voice has its own level and pan setting, and there are handy shortcuts, including options to send the rhythm to an existing multitimbral setup or to start a new setup. A neat touch is that the looping rhythm can be auditioned at any time by playing any of the lower notes on the keyboard; the individual drums can be played or recorded into the rhythm using the upper keys. As each percussion voice is selectable from any category — not just drums — you can build up some pretty off-the-wall kits if you wish.

The rhythm grid and lengths are set in the same way as the sequencer, and you soon become familiar with the process of either playing along with the metronome in real-time, or entering notes grid-style via the display. The metronome is a stored pattern, so you can modify this too if you like. Sequences, rhythms and arpeggios are transmitted over MIDI, although you need to set the Micron to Local Off mode first.

Memory & Categories

The supplied manual describes over 500 Preset programs and 32 multitimbral Setups. This was clearly inaccurate from a quick trawl through the synth, so I had another look at the Alesis web site and found an updated manual that also addresses several other important omissions. In fact, the Micron offers dynamic memory allocation rather than a fixed set of program numbers. Each time you save a program or a rhythm, the display tells you how much space remains. In the case of the factory set, there are approximately 600 programs provided, with space for around 400 more. Similarly there are about 150 Setups, over 240 Patterns and 300 Rhythms included, although the space available for more of these is quoted as a percentage. If this seems a little confusing, actually it isn't so bad in reality. Put simply, you can store about 1000 Programs, and probably more Setups, Patterns and Rhythms than you'll ever keep track of.

The category system implemented for programs makes a lot of sense in terms of quick retrieval, especially if the sounds you create fall into the preset slots of 'bass', 'lead', 'pad', 'sfx', and so on. The 'All' category gathers together every program in alphabetical order and a special 'recent' category keeps track of patches you played recently, very much like your computer remembers recent documents. Most usefully, 'faves' is an ideal means to gather patches together for a live performance, or simply for quick access.

However, the way categories are implemented means you do not have conventional patch locations to refer to. So if you wish to call up specific patches in Cubase, Logic and the like, this could be an issue. There are underlying bank and program numbers, but these remain unknown until you manually press and hold the relevant Programs, Setups, Patterns or Rhythms button, at which point the display yields the relevant information. You could record the action of program selection into the sequencer, but in order to select sounds from a list, you'd need all this information in advance.Round the back, the Micron loses one of the Ion's sets of audio outputs, but there are still two inputs, the full set of three MIDI connectors, and provision for connecting expression and sustain pedals. Not bad at all.Round the back, the Micron loses one of the Ion's sets of audio outputs, but there are still two inputs, the full set of three MIDI connectors, and provision for connecting expression and sustain pedals. Not bad at all.Photo: Mike Cameron

The Micron Sound Engine

  • Eight-voice polyphony.
  • Three oscillators per voice, with continuously variable wave shapes, sync and FM.
  • Two multi-mode filters per voice, with 20 filter types and extensive filter routing.
  • Three envelopes, two LFOs, and sample and hold.
  • 12-way modulation matrix, with 114 sources and 78 destinations.
  • One insert drive effect per voice.
  • Two master effects processors, including chorus, flanger, phaser, vocoder and now including reverb and delay.
  • Fully compatible with Ion programs.

Sounds & Multitimbrality

It shouldn't be too surprising to discover that the factory programs are a varied collection encompassing all that was impressive about the Ion, especially in terms of analogue-type sounds. In fact my only complaint is not with the sounds themselves, but with the seemingly random definition of the x, y and z knobs in many programs. As knobs are at a premium on the Micron, it's frustrating that these are often defined to control parameters like FM or ring-modulation amount or noise level (filter panning is another common alternative). There's nothing for it but to plough through them and reassign each knob to perform more generally useful tasks. I tended to choose filter or envelope parameters, oscillator waveforms or detune, or portamento amount, for example. Actually, almost anything works better than the choices made for you...

If the Micron's sounds delight with warm pads, thick basses and biting percussion, it's when you put them all together in multitimbral Setups that a new character begins to emerge. Perhaps inevitably, this involves a nod in the direction of dance music, but there is also a cross-section of split keyboards, layers and so on. Much of the loop-based stuff is inspiring, and it's both fun and informative to deconstruct the complex patterns, rhythms and keyboard parts.

Setups are organised in alphabetical order with each containing up to 26 parts! Yes, you read that correctly, and yes, this does mean you can quickly exhaust the Micron's eight-note polyphony — especially if you are a layering enthusiast. But plan things carefully, divide up your programs into zones over the full MIDI range and you gain tremendous flexibility — although you'll be in regular contact with those transpose keys unless you use an external keyboard.

Parts are added only as you need them, so there's no scrolling through inactive, unneeded menus. Each Part refers to a program and optionally, if sequencing is required, a pattern. You can select from the whole range of patterns available or simply pick the one already associated with the Program. Similarly, each part may have a Beat, which is merely a (non-transposable) rhythm, complete with its own key range, level and effects mix.

Parts and Beats may be latched so that they continue to play after you release the keys, and the Accomp key mentioned earlier is provided to turn off all looping patterns and rhythms for the entire setup at a stroke. As you play each part, you can activate the Latch function independently.

MIDI channels within a Setup are allocated according to the base channel defined in the Config menu. The channel number is increased automatically as new parts are created. This means if your base channel is 1 and you exceed 16 parts — as you well might — only the first 16 will be capable of sending or receiving MIDI data. Each part can be set to respond (or not) to the various performance controllers, and each has its own effects mix for FX1 (chorus, flanger, and so on). There's also an overall balance control between FX1 and FX2 (reverb, delay).


As I write this review, the Micron leads the Ion in its ability to reproduce rhythms and sequences, but I'd say that it's a safe bet these will be added in a future Ion OS update. However, the Micron still has one trump card in its hand, provided courtesy of a dedicated DSP chip, which takes it beyond the scope of the Ion. Rejoice, because the Micron has 'proper' effects.

If you recall, the Ion included chorus, a flanger, a vocoder and drive effects, but on the Micron, these are supplemented by a second processor capable of a selection of three reverbs (hall, plate and room) or three delays — one mono and two stereo algorithms. The longest delay time is 680ms, which is halved in stereo operation. Although this is not over-generous, it's still very welcome. Delays can be synchronised to the current tempo or can be set absolutely.

The quality of these effects is fine, and although you can't access their parameters in the modulation matrix or assign them for knobby control, they add a polished sheen to the Micron right out of the box. Sure, you probably have a better reverb available in your studio, but for the gigging musician they could prove invaluable.

OS Updates

On receipt of the Micron, my first task (as it often seems to be) was updating its operating system. This involved the tried-and-tested technique of playing a SysEx file to the synth, and went without a hitch.

Whilst on the Alesis web site, I took the opportunity to note the updates that have been created for the Ion since I reviewed it. Several new filters have been added and these are also present in the Micron. Of these, two extra comb filters are included, and these are an improvement on the older models, sounding far richer to my ears. Also, there is a new high-pass filter based on the Alesis model of the Moog four-pole ladder filter, which self-oscillates and sounds excellent. Because it wasn't based on an actual synthesizer, Alesis have apparently given it the initials of the engineer (Orly Pisa) who programmed the majority of the DSP sound engine — hence the references to the 'op filter'.


Summing up is easy. The Micron sounds fabulous; rich, lush, powerful, warm... everything you would hope for. Equally, it can be harsh, dirty or percussive. It is compact, solidly made and has more programming potential than anything this tiny has a right to. At the price, it's almost too good to be true.

By including effects and a surprisingly flexible sequencer/rhythm programmer, the Micron can perform backing-type duties currently beyond the scope of the Ion. Of course, what you lose compared to the Ion is obvious at a glance. The Micron's user interface has a whole range of ingenious shortcuts but these can't replace a bank of dedicated knobs, especially for lengthy programming sessions. With no software editor currently in the pipeline from Alesis, it's a comfort to know you can edit everything using the small display and available controls.

But then, perhaps you don't care about extensive editing — not everyone does. In this case, you could download a shed-load of ready-made Ion sounds from Alesis's web site, make a few tweaks and away you go.

Ultimately, it's a clear choice. At this end of the spectrum, the Novation K-Series is the most serious hardware competition. The Micron scores with its superior 'core' synthesis — ie. the quality of its analogue modelling, range of filters and modulation matrix. The Novations score in polyphony, effects, user interface and keyboard action. Actually, though, in some ways the Micron's biggest competition could come from the Ion itself. Once you test the sound quality of the Micron, coughing up the extra wonga for better access may become too tempting. For the time being, the Micron is tasty, almost as cheap as chips, and just as fattening!


  • Powerful analogue modelling at a tempting price.
  • Reverb/delay effects.
  • Built-in sequencer and rhythm programmer.


  • Keyboard lacks aftertouch.
  • User interface could be too minimal for some.
  • External power supply.


Diminutive it may be, but inside the Micron's compact frame beats the heart of an Ion whose analogue-modelling engine and eight-note polyphony have survived the transplant unscathed. Most of the Ion's high-resolution knobs have been sacrificed, but Alesis have worked hard to make the most of what's left. If you can live with the spartan user interface, you get a superb-sounding synth with built-in sequencer and rhythm programmer, all at a particularly tempting price.


£349.99 including VAT.

Numark +44 (0)1252 341400.