Overview
PPG closed in 1987, and its German distributor, Wolfgang Düren, founded Waldorf the following year. The Microwave of 1989 was Waldorf’s first product, and it picked up where the PPG left off: a rack-mount wavetable synth using the PPG Wave 2.3’s wavetables, with a custom chip designed by Wolfgang Palm himself.
Sound On Sound’s 1989 review describes an 8-voice module with two oscillators per voice and up to eight sounds at once in Multi mode. Like the PPG, it’s a digital/analog hybrid. The oscillators read waves from wavetables, and each voice then runs through a 4-pole, 24 dB per octave analog low-pass filter built on Curtis chips. A Motorola 68000 handled control. The module also has four separate mono outputs alongside the stereo pair, and memory for 64 single sounds and 64 multis, with the same again on a card. The Palm-designed chip is what generated the waves; Wikipedia’s PPG history describes it as the digital ASIC Palm built for Waldorf’s first product.
Waldorf followed it with the Microwave II in 1997, which moved the whole engine onto a DSP and added a multimode filter, and the Microwave XT. Vintage Synth Explorer describes the later models as more common but fully digital, so the original is the one with analog filters.
How its wavetables worked
Sound On Sound lists 32 internal ROM wavetables, each with 61 waves plus square, sawtooth, and triangle, so 64 positions per table as on the PPG. Wave storage is listed as 12-bit. The Microwave can also take 12 more wavetables over MIDI System Exclusive and another 12 from a ROM card. As with the PPG, the oscillator scans through a table under modulation, and the steps between waves are part of the sound. The move from the Wave 2’s 8-bit waves to 12-bit storage means each sample has 4,096 possible levels instead of 256, so there’s less quantization grain, though the tables themselves come from the same PPG lineage and keep their character.
Those SysEx wavetables are the only way new tables get in, and they come as Microwave SysEx data, not audio files. WaveStack doesn’t write Microwave SysEx, so there’s no route to the hardware. The tables did outlive it: Waldorf’s Blofeld combines the sound engines of the Q and the Microwave, and its wavetables include the PPG tables.
To make Microwave-style tables in WaveStack, build 64-frame tables and keep the steps between frames visible rather than smoothing everything into a perfect morph. Export at 256 samples per frame with Other tools for a lower harmonic count, or use a modern target like Iridium or Serum and let the synth handle playback. The analog Curtis filter has to come from the synth you load the table into; WaveStack only makes the waves.
Specifications
| ROM wavetables | 32 |
|---|---|
| Waves per table | 61, plus square, sawtooth, and triangle |
| User wavetables | 12 via MIDI SysEx, 12 on ROM card |
| Bit depth | 12-bit wave storage |
| Voices | 8, two oscillators each |
| Filter | Analog 4-pole, 24 dB/oct low-pass (Curtis) |
Frequently asked questions
How is the Microwave related to the PPG Wave?
Directly. When PPG closed in 1987, its German distributor Wolfgang Düren founded Waldorf, and the Microwave was its first instrument in 1989. It uses the PPG Wave 2.3’s wavetables, and its digital engine runs on a custom chip designed by Wolfgang Palm, PPG’s founder. It keeps the PPG’s hybrid layout too: digital wavetables into an analog low-pass filter. The main differences are the rack-mount format and 12-bit wave storage.
Can I load my own wavetables into the Microwave?
Only as Microwave SysEx data. Sound On Sound lists 12 user wavetables that load over MIDI System Exclusive, plus 12 more on a ROM card. The Microwave can’t read WAV files, and WaveStack doesn’t write Microwave SysEx, so there’s no direct route. If you want your own tables in a Waldorf, Iridium is the practical choice: it reads user wavetables and has its own WaveStack Export target.
What’s the difference between the Microwave, Microwave II, and XT?
The original Microwave of 1989 used a custom chip designed by Wolfgang Palm and analog Curtis low-pass filters. The Microwave II of 1997 replaced that with a DSP, which brought better mixing, more modulation, effects, and a multimode filter, but meant the filters were digital. The Microwave XT is a variant of the same digital generation. Vintage Synth Explorer calls the later models more common, which is part of why the original rack is sought after.
Which current Waldorf synths have the Microwave’s wavetables?
The Blofeld, released in 2007, combines the sound engines of the Q and the Microwave in a small desktop module, and its wavetables include the PPG tables the Microwave used. Waldorf’s newer Quantum and Iridium have their own wavetable engines, and Iridium loads WaveStack exports from its dedicated Export target. Check each synth’s page for the exact format it reads.