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Waldorf Electronics Microwave

Synthesiser Module

Article from Music Technology, January 1990

From the ashes of the classic PPG Wave synthesisers rises the Microwave - a synth expander that combines the unique qualities of PPG's wavetables with late '80s technology. Cooking with Simon Trask.

With its origins in PPG's classic but expensive Wave synth, the MicroWave brings wavetable synthesis to the masses. But can it roast the competition?

AS RECENT EVENTS in the eastern bloc have been demonstrating, the tide of change drowns all those who can't ride the waves. Whether you're running a country or running a company, if you don't respond to prevailing trends you'll be left behind. Sometimes that means overthrowing the very system by which you function.

In Eastern Europe we're witnessing the breakdown of a closed-system approach in favour of an open system. On a more humble level, developments in musical technology during the latter half of the decade have followed a similar path, one which has not been kind to the expensive single-manufacturer computer music system. The open-system approach made possible by, among other things, MIDI and the rise of computer-based sequencing has effectively atomised this particular closed system.

A good example of this is the now-defunct German company PPG's Wave system. By the mid-'80s the company had built up a sophisticated computer music system comprising the eight-voice Wave 2.3 synth, Waveterm B computer unit, EVU expander (2.3 in a rack) and PRK/PRK FD master keyboard. Up to eight system components could be linked together in a closed system using PPG's own digital communication bus, with the Waveterm at the heart of the system providing 16-bit sampling, additive synthesis, wavetable synthesis and (non-MIDI) multitrack sequencing.

When E&MM reviewed the Wave 2.3 and Waveterm A in May '84, the combination cost £8595 including VAT. But at that time it offered a degree of sophistication which simply wasn't available on a cheaper scale, and if you could afford the outlay it was worth buying into that sophistication. After all, compared to other computer music systems like the Fairlight and the Synclavier, the PPG Wave system was a bargain.

Unfortunately for the company, with the explosion in relatively cheap yet increasingly sophisticated digital technology in the ensuing years, it was the Wave system which came to be regarded as expensive, not to mention restricted. Who wants to be locked into one system when the MIDI modular approach offers so much more variety, flexibility and power? To make matters worse, the Wave system acquired a reputation for reliability problems - rather like a rottweiler, you had to treat it with care and even then it might bite you. Bowing to the inevitable, production of the Wave system ceased around '85-'86.

In 1986 the company produced two new units, both of which were, ironically, ahead of their time: the HDU hard-disk recording unit (the first such system to include time compression) and the Realizer (previewed E&MM April '86), a next-generation computer music system which was intended to sell for around £30,000-40,000 and combined highly sophisticated digital sound modelling (recreate a Minimoog in software) and digital effects processing with integral hard-disk recording and a multitrack sequencer which took PPG into the world of MIDI.

Unfortunately, the Realizer was a fantastic dream which never made it into production. What the company might have been better advised to do was move downmarket rather than (or perhaps as well as) indulging in their dreams. Which brings us to Waldorf Electronics and the MicroWave. The company is largely owned by Wolfgang Duren, who was responsible for the business side of PPG, while the MicroWave has been designed by Wolfgang Palm, the man who designed the PPG Wave system, HDU and Realizer. Not surprisingly, then, the MicroWave is fuelled by the same Wavetable-based approach to synthesis which helped to give the PPG Wave synth its highly distinctive and much-loved hybrid digital/analogue sound.

It certainly wasn't any deficiency in sonic quality or flexibility which led to the PPG Wave's demise. Several years later, wavetable-based synthesis has been reintroduced not only by Waldorf but also by Ensoniq on their VFX synth, where it's known as TransWave synthesis. It seems you can't keep a good sound silent!


THE MICROWAVE COMES in 2U-high 19" RACKMOUNT format with a charcoal-grey exterior whose sombre effect is quite nicely offset, it has to be said, by the bright red infinite-rotary dial on the front panel. Talk about Rudolf the Red-nosed Reindeer.

A 2 x 16-character backlit LCD window handles the display of current parameter(s) and their values, while a red Param/Value button below the window allows you to switch the display cursor between parameter and parameter value, while the aforementioned dial selects a new parameter or changes a parameter value accordingly. Reception of MIDI data on MicroWave channel(s) is indicated by a yellow pinpoint LED to the left of the LCD window, while a card slot below the window takes Access, Visa, American Express... No, no, ROM and RAM cards from Waldorf.

Finding your way around the MicroWave's large number of parameters isn't too difficult thanks to the 4 x 4 matrix display of parameter groups which takes up the right-hand half of the front panel. Successive presses of a Mode button cycle you around the matrix rows (with red pinpoint LEDs indicating the currently selected row), while four buttons below the matrix allow you to select a column. Where two parameter groups are indicated per matrix "node", successive presses of the relevant column button alternates between them. The MicroWave remembers not only which column you last selected for each row, but also which parameter and whether you selected parameter or value in the LCD window. Helpful features, particularly when you want to focus on editing a couple of parameters from different parameter groups, but the still frequent need to switch between parameter and value in the LCD does become tiresome. Two red dials, one for parameter and one for value, would've been much more fun. Apparently a certain well-known German software company (no prizes for guessing who) are currently working on MicroWave editor/librarian software, which can only be good news.

"The MicroWave is fuelled by the same Wavetable-based synthesis which gave the PPG Wave synth its highly distinctive and much-loved digital/analogue sound."

The MicroWave's polyphony is the same as that on the Wave 2.3 - eight voices. Not overly generous, perhaps, but it's worth bearing in mind that you get two oscillators per voice - many 16-voice synths are only so when you use one oscillator, ending up with eight voices when you use two.

Individual patches are known as Sound-programs, multitimbral organisations of up to eight of those patches as Multi-programs. You can access 64 Sound-programs and 64 Multi-programs in internal battery-backed RAM, and a further 64 of each type off ROM or RAM card.

The expander's rear panel provides MIDI In, Out and Thru sockets, four individual mono audio out jacks and a stereo output jack pair (mono summed output is possible if you use either one of the stereo sockets and set the MicroWave's global Stereowidth parameter to Mono).


THE MICROWAVE EMPLOYS what Waldorf call Dynamic Spectral Wavetable Synthesis. At the heart of the expander, stored permanently in onboard ROM, lie 32 Wavetables (the same 30 as were employed in the Wave 2.3 plus a couple of new ones). Battery-backed internal RAM provides capacity for 12 additional Wavetables which can be loaded into the MicroWave via MIDI SysEx data dumps, while a further 12 will be accessible off ROM cards.

Each Wavetable consists of 64 Waves, or digitally-stored waveforms consisting of 128 eight-bit samples and created by additive synthesis. A quick spot of arithmetic will tell you that that's a total of 2048 waveforms, but statistics don't tell the whole story (do they ever?). You can assign the MicroWave's oscillators to play any individual waveform as in traditional synthesis (in fact, Waves 60-63 in each Wavetable are the familiar triangle, square and sawtooth waveforms), but many of the Waves within each Wavetable evince only subtle changes in harmonic content from one to another. This is because the MicroWave isn't limited to playing single waveforms at a time, but can sweep through any number of them within a single Wavetable (even through an entire Wavetable, if you want), and is able to interpolate changes in harmonic spectra from one Wave to another (a feature which comes into its own with the Wave envelope, which we'll come to later). So Dynamic Spectral Wavetable Synthesis is quite an accurate description as well as quite a mouthful.


I'M NOT SURE WHAT PRINCE CHARLES would make of the MicroWave's internal architecture, but despite uncomfortably modern terms like the aforementioned Dynamic Spectral Wavetable Synthesis it's actually fairly traditional in nature. Two Oscillators per voice draw on two Wave modules to define the sound source (derived, of course, from the Wavetables). The audio output of each modulator and a third output from a noise source are then combined at a Mixer stage, where you can set the level of each source, and the summed output of the Mixer is then routed through a VCA and 24dB/octave low-pass VCF, after which it is passed through a Pan/Glide module before being routed to the outside world via 12-bit DACS and the stereo outs. In addition there are two digital LFOs and three envelopes (Wave, Filter and Volume) which have both 'hardwired' and assignable modulation inputs at the various audio stages just described. In fact, the MicroWave's many and varied modulation possibilities are among the most sophisticated to be found on any synth.

With patch names like 'Wave Kills You', 'Cut Me Leave Me' and, above all, 'Leones' Wet Dream', whoever's responsible for the programming on MT's review model deserves a medal for inventiveness. Unfortunately, the same thing can't be said about the sounds themselves, many of which only succeed in showing what the MicroWave is not good at. Still there are those who maintain that providing an impressive set of factory sounds encourages preset-itis at the expense of individual experimentation. But that's another story. I won't dwell on the sounds, as chances are many will have been replaced before the first shipment of MicroWaves hits the shops (which should be around Christmas time). So what can be said about the MicroWave? Leave most of the realistic instrumental sounds to the new generation of sample-based synths. The MicroWave's forte is synthesis in the traditional experimental sense, which isn't to say that it has an altogether analogue sound, more digital metallic with a strong analogue edge. And if there's one thing which can safely be said about it it's this: the MicroWave is not a nice synth. Harsh, dirty, aggressive, menacing, spiky, eerie, even soothing: yes. But not nice. Oh, and you need to watch out for your speakers, as it outputs at a very high level.


FOR EACH OF the two oscillators you can set octave (±2), semitone (0-12), detune amount (+63 to -64), bend range (0-12 semitones) and pitch mode (normal or fixed - fixed is whatever pitch you've set with the octave, semitone and detune parameters). Wave one allows you to select Wavetable (1-30), startwave (0-60/tri/squ/saw) and startsample (free - random/1-127); Wave two loses the Wavetable parameter because it automatically uses whatever Wavetable you've selected for the first Wave, but you can set independent startwave and startsample values for it.

The Volume section allows you to set independent volume levels for Waves one and two and a separate noise source (0-7 in each case), together with an overall volume level for the Sound-program (0-127). Next comes the Filter section, for which you can set filter cutoff (0-127) and resonance (0-127), while finally the Pan/Glide section provides you with pan position (L64-R64), glide (off/gliss/porta/Mgliss/Mporta), glide rate (0-127), glide mode (time/distance) and temperament (tuning - ln+, ln-, rn1, rn2, TT1-4).

"Despite uncomfortably modern terms like the aforementioned Dynamic Spectral Wavetable Synthesis, the MicroWave is actually fairly traditional in nature."

Most of the above should be self-explanatory, but the sophistication of the Pan/Glide section means it merits some discussion before we move on to the MicroWave's many and varied modulation possibilities. To begin with, both pan and glide are polyphonic, in the sense that they work on individual notes. In the case of glide, if you play one chord and then another, the lowest of the one will glide to the lowest note of the other, the highest to the highest, and so on. Polyphonic panning can be very effective where you're using velocity to modulate panning rate - you can experiment with cross-rhythmic panning, particularly in conjunction with a sequencer, which of course allows you to fine-tune the velocities of different notes. But I'm getting right ahead of myself (or should that be left - having all these notes whizzing around my speakers is confusing me).

So what's the difference between portamento and glissando? Simple. Portamento is a continuous pitch slide from one note to another while glissando is semitone-stepped. When the Microwave is set to Mporta or Mgliss, portamento and glissando can only be activated by MIDI portamento controller commands.

The glide mode parameter offers two approaches to keeping glides in a fixed time relationship (with themselves if nothing else) which apparently uses the glide rate as its basis. With Time selected, all glides take the same time, no matter what the pitch interval is; with Distance selected, all glides move at the same speed, so that while different pitch intervals result in different glide times they're at least in constant relationship to one another (to quote an example from the manual, a two-octave glide takes eight times as long as a minor-third glide). If you whack up the glide rate to maximum and set maximum sustain and/or release times for the volume and filter envelopes you can get some l-o-o-o-n-g glides which can be great for drones and background atmospheres.

Temperament allows you to select one of four preset tunings (as well as standard tuning there are reversed keyboard and two random tunings) or a tuning that you've programmed yourself. User tuning tables allow you to edit the coarse (any semitone) and fine-tuned (+63 to -64) pitch of every note in the entire MIDI pitch range to create non-standard tunings and scales.


THE MICROWAVE ALLOWS you to choose from a large number of internal and MIDI modifiers: LFO1, LFO2, Volume envelope, Filter envelope, Wave envelope and LFO envelope (LFO1 attack/decay) together with MIDI key track, attack velocity, release velocity, channel and polyphonic aftertouch, pitchbend, mod wheel, sustain pedal, volume pedal, pan controller, breath controller and four Controllers W, X, Y and Z, each of which can be assigned any MIDI controller code. Also available are Max (constant maximum modulation) and Min (constant minimum modulation value - off).

The two Wave modules and the Volume and Filter modules each have "hardwired' envelope inputs (Wave, Volume and Filter envelopes respectively) whose effect is governed by envelope amount, envelope velocity and MIDI key-track amount settings for each module. The volume and filter envelopes control amplitude amount and filter cutoff point respectively, as you might well expect, but the effect of the wave envelope on the Wave modules is far from conventional, as is the wave envelope itself - more on this later.

The above modules and the two-oscillator modules also each have two assignable modulator inputs to which any of the internal or MIDI modifiers listed above can be assigned. Mod2 has source and amount parameters, while Mod1 has source, control and amount parameters; in addition the oscillators each have a Mod2 quantise parameter (off-7) which allows stepped pitch changes to be produced from a continuous modulator input such as an envelope. I was hoping that resonance amount would also be modulatable, and lo and behold, resonance has its own mod source and amount parameters - which also means that you can modulate filter cutoff and resonance at the same time, from the same or different modifiers. If you're of an inventive disposition, things can get really interesting here. Also, as I mentioned earlier, the Pan/Glide module has its own mod source and amount parameters for auto- or dynamically-controlled panning effects.

Modulation values are assigned per module rather than per modifier, so the same modifier can have a different degree of effect on different modulator inputs (the amount range is +63 to -64, so the effect can be either positive- or negative-going). The parameter being controlled in each module is predetermined: the oscillator's pitch, the wave's wavetable, the filter's cutoff point and the volume's amplitude amount. Mod1 is more sophisticated than Mod2, in that while the source modifier directly controls the relevant module parameter within a limit set by the amount parameter, its actual degree of control is "scaled" by the control modulator. So whereas using Mod2 you could assign MIDI velocity to directly open and close the filter, using Mod1 you could assign the filter envelope as source modifier to control filter cutoff and use velocity as the control modifier to scale the envelope's effect. In this way you can put complex modulations under dynamic MIDI control, scale dynamic MIDI control with a complex modifier, scale a complex modifier with another complex modifier, or scale one MIDI command with another. And of course you also have the option of using Mod2 to bring in a second modulation source. On top of this, most of the onboard modifiers have parameters which can themselves be modulated by any of the onboard (including themselves) or the MIDI modifiers.

"The MicroWave is for anyone who thinks that today's synths are too polite, and for anyone who delights in getting creative and experimental with sound."

Which seems like a good point to look at the onboard modifiers in more detail. LFO1's parameters are as follows: rate (1-127), shape (sin/saw/pulse/random), symmetry (+63 to -64), humanise (off-7), rate modulation source and amount, level modulation source, sync on/off (for synchronising the two LFOs), delay (off/retrigger/1-126), attack (0-127) and decay (off, 1-127). Again, the modulation sources can be any of the onboard and MIDI modifiers listed earlier. LFO2 has a more modest array of parameters: rate, shape, symmetry and humanise. Symmetry alters an LFO saw wave from positive ramp through triangle to negative ramp, while if pulse wave is selected it adjusts the duty cycle from around 5% to around 95%.

Both the volume and filter envelopes are the familiar ADSR type, though the latter adds an initial delay stage. However, as nothing's straightforward on the MicroWave, each stage of each envelope has its own modulation source and amount parameters. Each stage's timing is set on a scale of 0-127, with maximum values generating truly lengthy times: just under nine minutes for the attack stage and just under six minutes each for the decay and release stages; a maximum value for the sustain stage means that it sits at the attack-level (ignoring the decay stage) until the key is released. The onset of the filter envelope can be delayed for around 36 seconds. The effect which the envelopes have (including their polarity) is determined at the modulation input stages of the individual modules.

Far less conventional is the Wave envelope, which has eight segments or stages, each of which has its own time and level parameters. What's more, you can specify any one segment as the Key Off point, so that any segments after this point will only come into effect when you release the note. Additionally you can select Loop on or off and a Loop start segment; whether this segment comes before or after the Key Off point determines whether the envelope will loop before or after you release the key.

As with the other envelopes, the Wave envelope isn't confined to the Wave modules but can be used wherever there's a modulation input - the results can be particularly spectacular when it's applied to filter cutoff and resonance. Applying it to a Wavetable is probably its most confusing application, but also one of its most sonically intriguing. It seems that the level parameters of each segment determine in some obscure way which Wave within the Wavetable each segment moves to. Or maybe not - the pre-release manual I had wasn't too clear on this (well, that's my excuse, anyway). I think I can be more confident in saying that the segment times determine how long it takes to get from one Wave to another, with the MicroWave interpolating gradual shifts in harmonic content to take it from one Wave spectrum to another - with particularly effective results when using looped segments and slow segment times on held notes to create some eerie metallic drone effects.

Now, it may seem churlish to raise a complaint about such a sophisticated modulation source, but all the same I found myself wishing the segments could be looped both before and after key release, instead of either/or. Because you can create rhythmic effects with this envelope, combining sustained notes with staccato notes having a long release stage could have generated some interesting results. I guess some people are never satisfied.


WHEN YOU SELECT Multi-program mode on the MicroWave, the expander becomes eight virtual Instruments which shares its eight voices between them dynamically. Per Multi-program you can set a global volume level and assign MIDI controllers to Controls W, X, Y and Z (in each instance overriding the, er, global global settings), program a 16-character name and decide on the number of active Instruments. You can also decide whether the MicroWave will respond only to patch changes received on the base MIDI channel (these select Multi-programs), only to patch changes received on the Instrument MIDI channels (these select Sound-programs for each Instrument) or to both.

Parameters per Instrument are as follows: Instrument on/off, MIDI receive channel (1-16), Sound-program (from internal or card memory), Key Limits Low and High (C1-G9 in each case), Velocity Limits Low and High (1-127 in each case) velocity curve (ln+, ln-, ex+, ex-, xf+, xf- and VT 1-4, ie. four user-programmable velocity response tables), transpose (±24 in semitone steps), detune (+63 to -64 - within a semitone up and down), Temperament (ln+, ln-, rn1,rn2, TT1-2), volume (0-127), panning (L63-R63), panning mod on/off and output routing (L+R/Outs 1-4). In addition you can turn reception on/off, per Instrument, of each of the following types of MIDI data: patch changes, pitchbend, mod wheel, channel aftertouch, poly aftertouch, volume, pan controller and sustain pedal.

A pretty thorough-going implementation, then - which makes the inevitable limitations of having only eight-note polyphony all the more frustrating. Still, combining two or more MicroWaves for greater polyphony is possible (if a little expensive), as the expander implements MIDI Overflow mode - notes over and above the polyphony of the instrument are passed on via MIDI to the next expander.


IN AN ATTEMPT to provide shortcuts for the programmer, Waldorf have come up with what they call Quick Edit facilities. These divide into two categories: Fast Access and Macros. Fast Access, as its name suggests, makes access to and therefore editing of related parameters much easier by grouping them on a series of LCD pages. For instance, you can edit the preconfigured envelope amounts of the Volume, Filter and both Wave modules from the Env Amount FA page, while the four parameters (ADSR) on the Envelope FA page allow you to edit the Volume, Filter and Wave envelopes at the same time. The changes you make in this way replace the existing parameter values, so making a copy of the original Sound-program first is a good idea.

"I can safely say that the MicroWave is not a nice synth - harsh, dirty, aggressive, menacing, spiky, eerie, even soothing: yes - but not nice."

Macros allow you to call up factory-defined Wave, Filter and Volume envelope shapes as a quick alternative to editing segment and ADSR parameters individually. Handy in some circumstances, maybe, but no real substitute for a nimble-fingered editing technique and thorough knowledge of the parameters - though such Wave envelope shapes as Slap Back, Wah Wah, Repeat Echo and Long Loop make intriguing starting points. If the Macro shapes aren't exactly what you want, you can always go into Fast Access mode and fine-tune them; if you still can't get what you want, then it's back to the individual parameters - and the feeling that you might have been better off starting with them. There again, how much fine-tuning you do depends on the complexity of what you want to achieve.

Waldorf have also provided a range of modulation Macros, some using LFO1 and others using LFO2 - allowing you to use two modulation effects at the same time. A variety of vibrato effects are complemented by the likes of Pseudo Leslie, Auto Wah Wah, Auto Panning, VelAutoPan and Stereo Echo. To me this is the most successful aspect of the Quick Edit system, but more for its creative possibilities than for any "quick-fix" philosophy.


THE MICROWAVE OFFERS two options for external storage of its onboard data: plug-in RAM cards and MIDI-linked remote storage devices such as your friendly neighbourhood computer running generic librarian software or MicroWave editor/librarian software.

In both cases you can store the entire onboard data, all Sound-programs, all Multi-programs and all Tables and Maps. You can send transfer requests via MIDI from the MicroWave (a handy means of transferring data directly between two MicroWaves), while the manual includes the necessary SysEx code sequences to allow you to create request files in, say, Hybrid Arts' GenPatch.

Finally, you can assign individual MicroWaves a device number, allowing them to be addressed separately for SysEx file transfer from, say, generic librarian software. The device-number range of 0-126 seems a trifle excessive, though!


THE MICROWAVE EXCELS in sonic areas where many of today's digital synths are not so strong and falls down where they succeed, making it in many ways a perfect foil for those synths. It has a very characteristic sound which could loosely be described as metallic analogue but can range in quality from pure, clean and crystalline to heavy, dirty, industrial - a synth for anyone who thinks that all today's synth are too polite, and because of its wealth of modulation possibilities a synth for anyone who delights in getting creative and experimental with sound.

I hesitate to say it's a programmer's instrument, because the concepts programmer and musician have become somewhat separated these days; let's just say it's a creative musician's instrument. Eerie bewitching metallic drones, extremely rude and dirty organ sounds, clanking industrial noises, biting percussive sounds, punchy (but not fat) bass sounds complete with spiky resonance effects if required, buzzsaw metallic drones, piercing lead sounds, complex self-modulating sounds which play with themselves for ever menacing atmospherics... The MicroWave positively encourages you along wilder shores rather than well-worn paths.

Now's your chance to get burnt by MicroWave and live to tell the tale.

Price £999.99 including VAT

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Also featuring gear in this article

Previous Article in this issue

Alesis Data Filer

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Spatial Awareness

Publisher: Music Technology - Music Maker Publications (UK), Future Publishing.

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Music Technology - Jan 1990

Gear in this article:

Synthesizer Module > Waldorf > Microwave

Gear Tags:

Digital Synth

Review by Simon Trask

Previous article in this issue:

> Alesis Data Filer

Next article in this issue:

> Spatial Awareness

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