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Getting Creative With Waldorf Microwave Synths

Published January 2003
By Richard Leon

The Microwave synths are complex beasts, so here are some hands-on tips to help you get the creative results you're after, without spending all your time programming.

Waldorf Microwave synth programming header artwork.Although the Microwave's specs may not look particularly special — two digital oscillators, a digital filter, a couple of LFOs, four envelopes, an arpeggiator, and some simple effects — these basics add up to far more potential for creative sound design than you might expect. Each of the elements has an interesting spin on it that makes the Microwave-series synths stand out from their virtual analogue counterparts. The standard ten-voice Polyphony may also seem low, but the sounds can be so ear-bendingly huge, detailed and brash that I find I don't often miss Waldorf's 20-voice expansion kit. Where other synths only start to shine when you pile on the notes, some sounds the Microwave makes are just too big for chords or complex Multis.

The secret behind the Microwave's sound is its oscillators. These use a wavetable system based on that pioneered by Wolfgang Palm in the PPG synths of the '80s. If you're expecting DX7-style clangs and weedy brass blarts from these digital oscillators then you'll be surprised to find that what you get instead is plenty of grunge and grit. This is lo-fi digital, 180 degrees away from the current fad for 24/96 quasi-perfection. The oscillators use eight-bit resolution instead of 12 or 16, and aliasing and other digital nasties are part and parcel of the Microwave's distinctive sound. Each oscillator keeps a wavetable — a sequence of 64 different but approximately related waves — in memory and can sweep through these tables manually using the knobs on the panel, or with the help of any of the internal modulation sources. These sweeps are another important element of the Microwave's unique timbres, and a big part of mastering the Microwave is working out exactly how to drive the wavetables to get the most out of them.

Getting Started

As a starting point, let's begin with something familiar — analogue simulation. The top three waves in each wavetable are set permanently to saw, square and triangle shapes. The analogue-like 24dB filter can take these and convert them into a good, if not quite perfect, rendition of those fat analogue brass, string and pad sounds everyone loves. If you use the Startwave knobs to skip to these top waveforms (they're the same in every wavetable), make sure no wave modulation is being applied, and add some outboard compression, the Microwave can do a good simulation of a Yamaha CS80 at its brassiest and most Vangelis-like.

But the Microwave is definitely at its best when the wave sequencing is at full tilt. This is where you find that these analogue waves can cause you problems. Once you start experimenting with wave modulation, you find it's easy for modulation sweeps to cross them, presenting the unwary programmer with unexpected results. The practical solution is to make sure that modulation control is always limited to a range between zero and 60, and this is easy enough to do. The Mod Matrix — about which more below — normalises inputs and outputs to a sensible range automatically. For wavetable sweeps, make sure that the total of the modulation amount and the Startwave knob is never more than 60, and you'll never have to listen to a sound that switches from a beautiful digital sparkle to a brassy blart when you least want it to. That said, you'll find that deliberately dipping into the sawtooth wave can sometimes be interesting when done with a random LFO source — you get a sound that starts digital, and turns analogue every once in a while. If you want to program a reverse sweep, offset the Startwave to +60 and then add modulation from zero to -60. Since there are two oscillators, you can create some wild and unlikely effects by modulating them in different directions from the same source.

The waves themselves are a mix of representative conventional synth techniques and sample-like waveforms. Many were imported wholesale from the original PPG Wave 2.x series. This may sound like a good thing, but the sound of the Microwave is only superficially similar to that of the PPG. The analogue filters in the latter make a big difference, and the sound of the PPG is generally much sharper and cleaner, with faster envelopes. The result is that the Microwave has some legacy waveforms that are perhaps less than essential. Worst space-wasters are the resonant filter simulations, which don't do anything you can't copy in other ways. You might think further filtering using the Microwave's own filter would create some nice double filter effects, but unfortunately that doesn't seem to be what you hear when you try it. Slightly more valuable are pulse-width sweeps, as there's no other easy way to create pulse-width modulation effects with the Microwave. The others provide a range of sound sources that vary between the subtle and the extreme. Describing all the waves in detail would fill most of this issue, so I'll just point you at the Carbon111 web site if you want that information (see 'Web Resources' box).

The easiest way to audition each wavetable is to set up an envelope — perhaps even the wave envelope — to sweep through the table fairly slowly. If you'd rather do it by hand, linking the mod wheel to the wave step can also be revealing. Don't forget that, while most wavetables include fairly smooth transitions between steps, the sound they create can be modified drastically by controlling them from a stepped modulation source. Because some waves have a weak fundamental under much stronger higher harmonic content, this can have the effect of stepping the pitch as well as the timbre.

Setting Up Custom Wavetables

It's one of the quirks of the Microwave that both the factory presets and the built-in wavetables are relatively unadventurous — they don't really show off the machine's capabilities. Creating your own waves and wavetables requires some persistence, but the results are definitely worth it. Unfortunately there's no built-in tool for this, so you need external software. The best option is undoubtedly Emagic's Sound Diver. Apart from being a supremely useful editing tool and patch librarian for other synthesizers, it also happens to offer the most comprehensive wavetable creation and management utility available for the Microwave.

The Microwave patch structure, as shown in Emagic's Sound Diver.The Microwave patch structure, as shown in Emagic's Sound Diver.

Sound Diver's editor gives you very simple and clear access to the hundred user wavetables and the waves that are used to put them together. Each wave is a single oscillator waveform, held in a special memory area that isn't accessible from the panel. To create a wavetable, you slot one or more waves into a wavetable buffer. There's no reason, apart from tedium, not to fill 60 wave locations with 60 waves of your choice. (Don't forget the top three waves are filled with analogue preset waves.) But it's easier and quicker to rely on the Microwave's built-in interpolation feature to smooth out your waves for you.

If you put a wave into slot zero, and a different wave into slot 10, the interpolation process will fill the slots one to nine in a 'join the dots' kind of way. You can repeat this for as many slots as you like until your table is full. You could even fill an entire table with just two waves, with the Microwave interpolating between them for all sixty steps. As a rule of thumb, the number of interpolation steps controls how smoothly, or not, the waveforms change as you modulate them. The more steps, the smoother the changes. Sound Diver labels these steps with an interpolation tag, to distinguish them from real waves held in memory. One 'gotcha' is that, during performance, the interpolation process isn't instant. When you select a wavetable — which usually means when you select a new patch — the Microwave thinks about your request for a noticeable fraction of a second while it calculates the required interpolations and copies the resulting table to the active oscillator buffer.

It's yet another quirk of the Microwave that, if you naively expect this process to morph timbres (for example fading smoothly between a square and a sawtooth) you'll be in for a surprise. The interpolation actually works on wave shapes, and these are only indirectly related to timbre. To interpolate timbres smoothly, you'd really need to work out the spectrum of each wave and interpolate between those instead. That's a much bigger job, and one that would leave the Microwave's processor spinning its wheels for an hour or two instead of the fraction of a second that the simpler kind of interpolation needs. But this isn't a bad thing, because the result is that you get a serendipitous smooth-ish blend of new waveforms that bears some resemblance to the originals, rather than a predictable sweep. While it's not totally controllable, it also leaves some room for surprises.

Generate Your Own Waves

If you can't afford Sound Diver, there's also Soundtower's editor, which isn't as sophisticated, but will do the job at a pinch.If you can't afford Sound Diver, there's also Soundtower's editor, which isn't as sophisticated, but will do the job at a pinch.If you prefer to specify wave spectra, rather than wave shapes, Sound Diver includes an editor that lets you perform additive synthesis for each wave, using partials from the fundamental up to the painfully shrill 63rd harmonic. This sounds fun, but in practice anything beyond about the tenth harmonic will usually drive you and your dog insane, so it's better to make interesting changes with the lower harmonics than to literally pull out all the stops.

In any case, additive synthesis isn't the only option. There's also the UPAW (User Programmable Algorithmic Waveform) system, which can use FM, pulse-width modulation and other algorithms to create wavetables. With UPAW you can create a range of traditional clangy, buzzy and otherwise very digital wavetables, with interpolation controlled automatically. In practice, UPAW is an excellent digital synthesis tool kit and, although the learning curve isn't trivial, you'll find it's capable of truly original digital sound creation.

The µwave+ utility makes additive synthesis for wavetable creation easy.The µwave+ utility makes additive synthesis for wavetable creation easy.If you can't afford or don't want Sound Diver, Soundtower make a Microwave editor for $35. It's not quite up to Sound Diver's standard, but it does give some degree of control over waves and wavetables.

Waldorf's own web site also includes some handy downloadable wavetable hacking utilities. While these aren't in the same league, they give you an alternative way in. Anyone who always wanted a Fairlight, but could never afford one will enjoy playing with µwave+. This lets you control the level of each harmonic up to the 50th in each of the 60 waves in a table. It's fairly unwieldy in use, but capable of interesting results with a little practice.

wav2µwave creates interpolated waves from your favourite samples.wav2µwave creates interpolated waves from your favourite samples.wav2µwave offers extreme interpolation, letting you pick small chunks of two real samples and interpolate between them. Again it's quite crude, and not at all intuitive, but can be fun to play with. Raw2wave is a slightly strange picture-to-wavetable conversion tool. You can use it to define harmonic content graphically — although this requires being able to draw with pixel accuracy, which is more than most people have patience for. It's much easier, and more creatively lateral, to use it to convert pictures of your friends, neighbours, pets, enemies, and so forth to wavetables. Finally, those with über-geek skills will appreciate having the UPAW C source code available to play with. The code compiles to a command line program which can create SysEx wavetable files ready for dumping via MIDI.

What about converting samples to wavetables? You can't sample directly into the Microwave — it doesn't have the memory for samples, and isn't designed for sample playback. You can create sample-like effects, but this is an incredibly tedious process. The least painful way to do it is to take representative screen grabs of single cycles throughout a sample (any sample editor will do the job here) and convert them to waves visually. You have to fade each wave to zero at the extremes to avoid nasty rasps and clicks at the zero crossings. There's no utility that can do this automatically. If you want the option, you'll either need to steel yourself for lots of late nights and coffee, or start saving for Waldorf's big Wave, which has resynthesis software for exactly this job built in.

The Wave Series

It all started in the early '80s with a digital synth Wolfgang Palm created for synth rockers Tangerine Dream. This was based on an early version of the same wavetable system that's used today. As an instrument, the original experimental design was too unwieldy and expensive to sell, and was eventually packaged into the PPG 2.x series. This combined eight digital oscillators with digital envelopes, analogue filters and an arpeggiator. Although the PPG series is regarded as a classic, PPG as a company overstretched itself and disappeared, leaving the wavetable idea to languish in the studios of collectors and working musicians.

Then came new owners Waldorf, and the new wave series. Waldorf hired Wolfgang Palm to create an updated model, and the original Wave was born. It was, and still is, a hybrid monster, with a huge panel, digital oscillators, analogue filters and a sample analysis system that converts any given sample into a set of wavetables. Released in 1993, it was at least 10 years ahead of its time, although it took Waldorf at least half that time to iron out all the bugs! It also had a huge, professional price.

The Microwave was an attempt to repackage the technology in a more accessible form. The Microwave Mk I used digital parameter access, which made it almost impossible to program without a patch editor — although it did have a rather funky speech synthesizer built into it. The Mk II model replaced the Mk I's analogue filters with digital simulations, and unfortunately dropped the speech synth. Then came the XT, which added 44 knobs, and finally allowed proper hands-on programming. An XTk model added a keyboard. In terms of SysEx, the XT and the Microwave Mk II are functionally identical. (There was also a drivebay-sized Microwave system marketed by Terratec for a while. This had some drawbacks which made it less easy to work with than the hardware versions. But again, it was functionally identical.)

The differences between the Wave and the Microwave XT are smaller than you might expect. Apart from a smaller LCD and digital rather than analogue filters, the sound engine is very similar. The XT also lacks the Wave's resynthesis features. If you want those, you'll need external software.

Mixer & Filters

The Microwave's mixer seems conventional enough — you can add noise and a ring modulator output as well as the sounds of the oscillators themselves — but has an intriguing Quality page which can be used to add even more dirt and nastiness. Setting Aliasing to anything other than Off allows high frequencies to fold back audibly. It's a subtle effect that's most obvious with medium- to high-pitched notes, and sounds a little like extra ring modulation. Timequant sacrifices pitch accuracy for yet more digital grunge and fizz. Clipping can create insane digital shrieks by distorting waveforms into oblivion. Saturate is the polite option here, and should be chosen for analogue simulations. Overflow wraps saturating waveforms around the extremes, so where the waveform would usually clip it dips downwards instead, creating a spray of extra overtones. This one page on its own should be a favourite with every Microwave owner. It creates and enhances the Microwave's digital character at least as much as the oscillators themselves do. There's also an Accuracy setting here, which adds some pseudo-random detuning for extra analogue-style fatness.

Sound Diver's wave editor lets you draw waveforms or use additive synthesis to calculate individual waves.Sound Diver's wave editor lets you draw waveforms or use additive synthesis to calculate individual waves.Past the mixer are the filters. There's a lazy 6dB high pass, but it's not good for much beyond removing bass thumps and floppiness, and cleaning up the low end of pads so they don't dissolve into mush. The other filter is more useful. Its standard analogue LP/BP/HP modes sound as you'd expect them to, and the Dual LP/BP is good for Jarre-esque phasing — later OS versions have some notch and band-stop filters which are even better for this. The Sin(x)>LP, FM and Waveshaper filters are ideal for adding digital punch to sounds. They seem to be good at adding hollowness, body and controlled distortion, more or less in that order, and are excellent for spiky and chunky basses and shrill leads. The S&H filter provides the ultimate in digital destruction, and can reduce most sounds to a wall of distorted digital noise. It's too powerful for most musically recognisable sounds, but should be your first choice if you want something aggressively abstract.

Creating New Patches

Sound Diver let's you interpolate between waves to create variations.Sound Diver let's you interpolate between waves to create variations.If fine control of all the main sound parameters sounds too much like hard work, there's an easy way to explore what the Microwave can do — the built-in patch randomiser. Hold down the big red Shift button, push the Utility switch, twirl the big red knob to the far right and then back a step, and hit Utility again. This will present you with some astounding sounds — monstrous wails, shrieks and screams, twittery aliased digital noise, carpet-wobbling throbs and drones, and tortured short-wave radios. You'll usually find that these sounds evolve over seconds and even minutes. They'll also change with every note you play, respond to your playing in unexpected ways, and generally sound like nothing you've ever heard coming from a synthesizer before.

The bad news is that virtually every random patch you get will be rather abstract — great for industrial experimentation, but not easy to place in the context of the kind of music most of us willingly listen to. But this is really a blessing in disguise. Once you understand your Microwave you can make some fairly simple changes to tone down the extremes and give yourself something more playable. A lot of the complication comes from the modulation matrix, which includes some creative innovations that you won't even find on a big modular. Understanding this matrix can go a long way towards unleashing the full power of the machine.

If you've ever used the modulation matrix on other machines, the source and destination settings will be obvious enough. There's the usual range of LFO, envelope and MIDI sources, with a couple of useful extras including MIDI clock, release velocity (your keyboards probably won't handle this, but your sequencer might) and a useful control delay. You also get the usual range of destinations, including pitch, filter cutoff, waveform, noise and ring modulation amount, and various envelope parameters.

Buried in the list of sources are four intriguing extras called modifiers, which are at the heart of the Microwave's creative possibilities. They let you process and combine any of the sources, and then route them back to the main matrix. The processing can use basic arithmetic and Boolean AND, OR and XOR operations. There are also max value, min value, lag (glide filter), a ramp generator, a differentiator and a sample and hold. If this sounds like rocket science, that's because it can be — at least when you're trying to think of creative applications for the first time. But it's not as bad as it looks, especially if you dip into it slowly. As a starting point, let's say you want to control the LFO2 amount so that it only kicks in when you step on the sustain pedal. Use the multiplier option to multiply LFO2 by the sustain pedal output as follows.

Source #1Source #2TypeParameter
LFO2Sust. Ctr[*]127

The sustain input will be zero or one, depending on whether or not the pedal is pressed. To hear the effect, take the output of modifier one through the modulation matrix and route it wherever you want — filter, pitch, or anything else.

Modify #1+60Pitch

That's a very simple example. The power of the modulation matrix comes from being able to combine interesting sources in interesting ways. For example, try the following setup:

Source #1Source #2TypeParameter

Set both LFOs to a fairly slow speed, and route this setup to the Osc 1 wavetable position. The XOR effect can produce a semi-sequenced S&H-like effect. What you hear is something that's clearly not totally random, but not totally predictable either. Setting Type to AND or OR will give variations on this theme. By syncing both LFOs to the clock and running them at different but related multiples, you can create a repeating and predictable step sequencer effect. (Given that the longest clock sync period is 128 bars, this can be a very big step sequencer indeed!) Changing wave shapes will give you different sequences, as will other Type settings. As is often the case, you can get a long way by experimenting at random here.

For a more complex example, let's create an effect for live use that sweeps the filter upwards when we stomp on the sustain pedal — useful for modifying sequenced dance music. Use the sustain pedal input and route it through the ramp processor.

Source #1Source #2TypeParameter
Sust. Ctr<ignored>Ramp<variable>

This will start a ramp whenever the sustain input changes from zero to one. The parameter controls the ramp time. Settings are arbitrary, so you'll need to experiment to find the time you want. You now have a filter sweep that acts just like a spare envelope, and can be triggered at will.

The Microwave's envelopes are straightforward enough. There are four of them — two ADSRs for the filter and amp, a four-stage envelope with sustain for general use, and a massive eight-stage envelope with programmable loop points for controlling wave sweeps. The big problem with the envelopes is that the attack is too slow. If you want sounds with an instant-on slap, you can fake this by sacrificing one of the LFOs for envelope use, setting it up as a slow square wave source synced to the keyboard, and using the modulation matrix to route it to the amplifier level. The results still tend to be disappointing, though, and it seems to be impossible to get the kind of analogue-style punch from the envelopes that some other machines can provide.

Still, the modulation possibilities go a long way to making up for this. You can use the modulation matrix to patch any envelope to any destination, although the wave and filter envelopes are hard-routed via panel knobs for convenience. You can also do clever stuff, such as routing the wave envelope through a differentiator to turn the ramps into constant steps — turn on looping, and again you have a programmable eight-way step sequencer, with time and amount individually variable. A useful trick here is to use this to control timbre through oscillator sync. Turn on the sync for oscillator two, feed the processed wave to oscillator two's pitch, mix in some ring modulation, and you have an extremely digital-sounding sequence. Because the Microwave's wavetables aren't analogue, sync tends to sound extremely harsh. For even more extreme effects use the red Wavetable selector knob to sweep through the wavetables by hand until you find one that sounds good. For more extreme effects still, you can use the wave envelope to sweep the wavetables while all this is happening — although you'll often find this dissolves into digital noise for all but the most mellow of wavetables.

The Microwave's Arpeggiator

Multi mode with arpeggiation is one of the coolest things you can do with a Microwave, creating mini songs and loops with a single key press. The arpeggiation isn't entirely obvious, so I'll explain it in detail here.

In Sound mode, the arpeggiator plays one of 16 fixed patterns, or a user programmable one. This can be driven either by internal tempo control, or external MIDI clock. The arpeggiator includes up/down/random modes, and MIDI sync includes useful tempo subdivisions, including triplets. Programming is a slightly tedious process of setting up a step count, then moving through each step in turn switching a trigger on or off. While it's fiddly, the display shows clearly what's happening.

In Multi mode you can layer sounds so that each is arpeggiated with its own settings, or you can create custom settings for that Multi. For the former, make sure Active is set to Sound Arp, and that the User option is selected under Pattern. For the latter, you can select independent patterns and clock subdivisions.

One obvious application is a four-on-the-floor kick and a jingly hi-hat. Use a two step sequence with a suitable subdivision ratio to get two kicks per bar. Then dial up one of the many hi-hat sounds for another instrument, and play with the patterns till you find something that works. From here it's easy to add a throbbing repeating bass. With larger clock ratios it's possible to create sequences where sounds cut in and out in a very complex pattern. A good creative tip is to try this with non-percussive sounds, to create unique repeating textures. You can even use pad sounds to flesh out the mix.

Patch Libraries

Not everyone wants to spend all their time programming. If you're looking for the easy but accessible option, Waldorf's site includes some patch sets, both for free and for the cost of a minor dent in your credit card. In the former group are all of the various factory sets that have been created over the years. As with many factory presets, these don't really show off the instrument at its best. Better options are the two free user-created sets on the site, which are much more creative. There isn't room here to pick out individual patches for praise, but if you own a Microwave these sounds are essential. It's also worth downloading the No Filter set, just to demonstrate the power of the wavetable system with minimal extra processing. All the above (and more) are free from Waldorf's FTP area.

Want sounds? The Waldorf FTP site has plenty for free, including some from SOS contributor Paul Nagle.Want sounds? The Waldorf FTP site has plenty for free, including some from SOS contributor Paul Nagle.Waldorf also offers a collection of commercial sound sets for 50 Euros plus shipping. The techno/dance and ambient sets are the ones to go for here, with the industrial set trailing not far behind. If you have the user sets, these commercial collections will expand the range of sounds available, rather than sending you off in new and completely unexpected directions. So don't expect any real surprises — just some very useful sounds with plenty of character. The rest of the commercial sets have perhaps less of an obvious immediate appeal, although if you're relying entirely on the Microwave for all your sound generation, they can still be worth considering. The production set offers some relatively polished patches, and the analogue simulation set will be useful for anyone looking for some relatively restrained and much more familiar sounds.

One thing to note here is that the Microwave has some SysEx problems. An attempt to update the entire memory can leave it chewing over part of what you sent while you look at a 'reorganising memory' message. The Microwave doesn't get confused about the patches it misses. It just diverts its attention to an internal garbage collection and defragmentation routine in the middle of a dump — sometimes more than once. Updating the system firmware doesn't seem to make a difference. In practice this means that you'll almost certainly have to send a dump from your sequencer or editor two or three times before all the patches appear as they should.

To get the best out of all these patches, it's worth feeding the Microwave's outputs to your outboard gear for further enhancement. Without post-processing, the Microwave's character can be a touch flat and remote, and, at its very worst, it's reminiscent of the digital blasts and zips from an old eight-bit microcomputer. But compression seems to add body and bring out the detail, and it also enhances any analogue simulations you're attempting, so much so that you might want to consider leaving it patched in permanently. I find that the multi-band compression on my Dbx Quantum seems to be particularly effective — there seems to be an unexpected synergy between this machine and the Microwave, more so than with other synths and other Finalizer-type tools, which seems to bring out extra depth and weight in the sound. Simpler and cheaper compression can be nearly as helpful too, especially if you use more extreme ratios — at least 4:1.

Microwave Winner

It would easily have been possible to fill twice this space with information about the Microwave. Once you get past its cosmetic attractions, it turns out to be one of the deepest non-modular synthesizers you can buy, and it's possible (with some effort) to do almost anything with it that you can do with the much more expensive Wave. Now, if only it'd heat up slices of pizza as well...

Web Resources

The Carbon111 site is a supremely useful resource for all things Microwave related. Includes new wavetables, links, programming tips, and other information. It also has useful verbal descriptions of each table, with spectral and waveform plots for each of the waves.

Soundtower's site has a Microwave editor available for download.

The Consequence's Waldorf page has MP3s and programming information.

Here's are some useful and practical descriptions of the Microwave's wavetables.

Published January 2003