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Waldorf Microwave 2.0

Wavetable Synthesizer By Paul Nagle
Published August 1995

Paul Nagle takes home a version 2.0 Microwave and discovers why this extraordinary instrument continues to enjoy such a long and illustrious life.

The Waldorf Microwave is a bit of a maverick in the world of hi‑tech instruments. This unassuming 2U rack synth is only 8‑note polyphonic, has no built‑in effects, and creates its sounds from a series of sampled waveforms processed through a traditional analogue filter. It doesn't offer realistic pianos, drums or saxophones, nor does it attempt to. The fact this instrument is still in production in its sixth year suggests that there must be something appealing hidden behind that shiny red knob; for a synth to be significantly enhanced after so long is almost unprecedented.

The ongoing Microwave upgrade policy has now reached version 2.0, which doubles the number of wavetables (the building blocks employed by the Microwave's unique synthesis method), as well as adding several important tweaks to the operating system. Furthermore, existing owners can upgrade for a mere £82.25 (inc VAT) — how many other synths you bought six years ago can boast so much? Perhaps it is this ongoing committment that inspires such near fanatical devotion amongst Microwave owners?

Since this is intended to be more of a revisit than a review, I suggest you rummage through your old Sound On Sounds until you find December 1989. For those of you with a filing sytem like mine, let's take a quick Microwave refresher course before moving on to some of the features new in version 2.0.

Microwave Warm‑Up

Basically, the Microwave features 16 digital oscillators (two per voice) plus a noise source, all processed via conventional filter, envelope, and pan modules. The synth can be used in single or multi mode, the latter allowing up to eight individually addressable voices to be assigned and routed through the two stereo or four mono individual outputs. The front panel is sparse, having a small LCD, card slot, power switch and only seven buttons with which to wade through its many edit pages. There is no headphone socket and no dedicated volume control — presumaby because most rack gear is turned up fully and left that way? Edits are performed using the distinctive red alpha dial, which is a little lightweight for my tastes (lacking the positive action of the Emu continous data knobs, for example), but you do grow used to it. A dazzlingly bright red LED indicates the level in the 4x4 matrix of parameter pages, through which you navigate using five of the buttons.

Since the display is just 2x16 characters, it can mean lots of pages and lots of button‑pressing even to change something as simple as the volume envelope — since each parameter is on a separate page! Realising this, Waldorf have provided quick edit pages which, combined with the generous eight edit buffers, goes a long way to making this synth usable, even without a computer‑based editor. Actually, you soon get to know your way around, and after a couple of days you hardly need to refer to the manuals at all. Speaking of the manuals, they cover performance, programming, and the various system upgrades and are worth a good read. Quirky humour is present and welcome and some of the programming suggestions make me wonder why on earth the supplied factory sounds are, with only a few exceptions, so naff?

Notable features of the Microwave are its wonderful, big 4‑pole filter, which is capable of self‑oscillation. Both cutoff frequency and resonance are accessible by any of the modulators or external control. In these times, when so many synths have a glorified tone control pretending to be a filter, the power of a real filter cannot be underestimated when it comes to sound creation. Welcome too are the portamento and glissando modes, which allow both smooth and stepped transition from note to note — ideal for those old monosynth emulations. But the real heart of the Microwave is in its unique sound generation system — wavetables — which are derived from raw sample data stored in ROM.


Since wavetables are what separates the Microwave from just about everything else on the market, it is important to appreciate how they work. Version 2.0 of the Microwave operating system provides a total of 64 basic wavetables plus 12 internal user wavetables (and 12 more on a card), each 'containing' 64 waves. This seemingly vast number of sound sources is better understood when we realise that not all the waveforms live in ROM — many are dynamically created (or 'interpolated') by the processor from waves in the current table. This technique both saves memory and gives the Microwave its unique 'dirty' sound. Compare this to the Korg Wavestation, which simply fades cleanly from one ROM sample to the next. Only one wavetable can be active at a time on the Microwave, but each oscillator can reference different areas of the table and progress through it independently. Of the 64 waveforms in a table, the last three are always sampled triangle, square, and sawtooth waves and may be used to create more traditional synthesizer sounds if no modulator is applied.

By specifying a negative slope for one oscillator's wave envelope and a positive one for the other, both can sweep in opposing directions creating some truly monstrous sounds.

Although wavetables may be selected by name, each wave is referenced only by a number. Interesting ranges of timbres can be found by slowly sweeping the table, but you need to devise your own method for remembering the positions of your favourites. Movement through the wavetable is achieved using a special dedicated 8‑stage envelope, which may be looped or modulated by a variety of sources. By specifying a negative slope for one oscillator's wave envelope and a positive one for the other, both can sweep in opposing directions creating some truly monstrous sounds. The timbral transitions can be either audibly stepped or smooth, with no detrimental effect on polyphony. However, this has some limitations: the processor is not omnipotent and some harmonic changes are simply too complex to calculate smoothly, as you hurtle through a table at a hundred miles an hour. Strangely, the result is often quite interesting and certainly distinctive. User wavetables may only be generated using computer‑based software — checkout Mark Of The Unicorn's Unisyn, X‑Or, Emagic's SoundDiver, Sound Quest's MIDI Quest or the Geerdes dedicated editor if you're interested in such exotic things. Sadly, it does not seem possible to name user wavetables, so you need to use your ears to check which ones are currently in use.


The Microwave is a synthesizer that dares to be different. It simply gets on with what it's good at, delighting in spikey, mean sounds which cut through a mix, while also being capable of warm pads, powerful brass, and shimmering glass and bell effects. If you're familiar with Tangerine Dream's Exit album, many of those weird PPG digital tones are typical Microwave territory.

The new wavetables really add to its armoury with some great oscillator sync waves (it has no genuine oscillator sync of its own), fuzzed and distorted sounds, and some fun mixtures containing voice samples and other oddities. The powerful filter and varied portamento are great for the more traditional lead synth roles. If this synth has a weakness at all, it is in the bass department where some of the wavetables fade noticeably. Since many of the available sound cards specialise in bass sounds, perhaps I just haven't discovered the rich seam of waves which work well in the lower octaves?

During the review period, I can honestly say that I didn't miss built‑in effects. A smattering of reverb is really all the Microwave needs — anything else is like painting over good wood! It didn't take me long to surpass the majority of the dull factory‑supplied sounds, which left me feeling pretty smug. Did I like it? You bet!

Microwave Links — Waldorf On The Net

For the Internet surfers out there, Waldorf have their own World Wide Web page accessed at: www.waldorf‑ From here you can link to the FTP site for wavetable utilities, SysEx documentation and new sounds, or take a look at back issues of the Waldorf user forum.

If you wish to subscribe to the forum, send an email to: user‑forum‑ and include the keyword "subscribe" in the text. Much of it is pretty technical stuff but it's good to see that the Waldorf programmers reply with genuine enthusiasm to questions posed there. So get your surfing kit on and take a look.

Version 2.0 Enhancements

  • 32 new internal factory wavetables.
    3 Sawtooth waves with oscillator sync.
    3 Pulse waves with oscillator sync.
    3 Sine waves with oscillator sync.
    Pulse waves whose width is modulated.
    Sawtooth waves whose width is modulated.
    Light metallic fuzz waves.
    Powerful distortion waves.
    More powerful distortion waves.
    Synced fuzz waves.
  • K + St. 1‑3
    Karplus Strong series — ideal for plucked string type sounds.
  • From 1 to 5
    Robot voice counting to 5.
  • 19 / 20
    Saying "19 20"
  • WTrip 1‑4
    Rich and varied selection of waves.
  • MaleVoic
    Metallic vocal sound.
  • LowPiano
    Like the bottom end of a piano.
  • ResoSwep
    Resonant filter sweep.
  • XmasBell
    Ring‑mod‑like harmonic series.
  • FM Piano
    Convincing DX7 piano waves.
  • FatOrgan
    Even harmonic series — the name says it all.
  • Vibes
    Hollow metallic vibes.
  • Chorus 2
    Rich phasing chorus — the best of the lot!

The descriptions are intended to give a flavour of the harmonic progression of each wavetable when heard with a single oscillator and the filter fully open. In use, individual portions of each table can yield a wide variety of timbres.

  • Volume control Amplitude of two oscillators as well as the noise source can be modulated individually. Six new parameters cover this facility.
  • LFOs: Both Low Frequency Oscillators now have sample and hold — LFO2 can also create a waveform whose rate is phase shifted from LFO1, making for some very rich and subtle vibrato effects.
  • MIDI Clock Control: MIDI Clock may now be used as a modulation source. Don't all you wavesequencing freaks get too excited though. Sadly, you can't do fancy things like trigger envelopes, synchronise LFOs, or step through wavetables at the MIDI Clock rate. What you can do is use the MIDI Clock as a kind of controller, where fast equals a high controller value. In practice, you can programme LFO filter sweeps that speed up with music tempo or even modulate the time or level of the wave envelope.
  • Four new allocation modes for monophonic playing (Multi mode):

RETRIG — new notes only activate a voice if not already active or the new note is higher than the current one.

SGL‑RETRIG — attack portion of the envelope only triggers if no current note held down, otherwise just new pitch and velocity values are used.

L‑SINGLE — attack portion of the envelope only triggers if no current note held down, otherwise only new pitch and velocity values are used if new note is lower than one currently being played.

H‑SINGLE — as above, but new pitch and velocity values are only used if the new note is higher than one currently being played.

  • New panning mode which can disable an instrument's panning parameters or invert them (Multi mode).
  • Glide & Portamento — new functions for fingered playing (ie. only invoke the glide if another key is already pressed — a handy performance thing).
  • SysEx speed select (fast/slow) to allow communication with slower devices/software.
  • Example Disk — also included is a disk containing some example user wavetables and software (for the Amiga, Atari, MS‑DOS and Unix platforms) to transmit the wavetables to the synth. More interesting still are three MIDI Files which contain SysEx dumps of banks of sounds created by Waldorf. These sounds drastically improve on the factory sounds — especially where new user wavetables are involved. All you need to load them is a MIDI sequencer capable of replaying Standard MIDI Files.

We'Re Cooking! — New Wave Sounds

Three MIDI Files containing SysEx dumps of 128 voices and multis are provided on disk. They are intended to show off the new v2.0 wavetables and do so quite well. Here's a quick run down of some of my favourites:

  • Prepared Piano marvellously playable and hardly like a piano at all.
  • ComputerWorld, Techomusic, Revolution all using new 'speech' wavetables.
  • SlowSweep rich, harmonic sweep. Lush and classy.
  • Sacred Chorus mysterious solo voice‑like patch with mod wheel controlling subtle mouth movements.
  • Alien Visitor a Theremin‑like wail right out of those early sci‑fis.
  • MW‑Receiver spooky radio‑noise, complete with robot voice.
  • Disted Bass notable in that it is the only half‑decent bass in the collection.
  • Wave Choir unusual choir that does weird electronic things when you move the mod wheel.
  • Sync Lead the Microwave's own wavetable version of a sync sound. Similar to the real thing but with that special graininess.
  • Elektra Sync an unusual pad.


  • Unique wavetable sounds.
  • Great analogue filter.
  • Programming sounds is addictive!


  • Only 8‑note polyphonic.
  • Quite expensive, but rare objects always are!
  • Factory sounds only hint at what this synth can do, so be prepared to programme your own sounds.


This synth is not for everyone and does not follow the 'everything in one box' philosophy. Instead it produces raw, powerful and rich sounds that range from subtle through to gritty and aggressive. If you've already got enough chiffy flutes and realistic trombones in your sonic arsenal and want to tackle a wild synthesizer, the Microwave could well be for you.