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Waldorf M

Wavetable Synthesizer By Rory Dow
Published April 2022

Waldorf M

Waldorf return to their roots with a modern take on the classic Microwave.

Wavetable synthesis was a revolution when it first arrived in 1978. Pioneered by Wolfgang Palm, the PPG Wavecomputer 360 was the first synthesizer to use this new technology. It had a few shortcomings, chiefly a lack of filters, that stopped it from becoming a big seller but its successor, the PPG Wave, was a hit.

The PPG Wave was the perfect marriage of digital oscillators and analogue filters, and the PPG Wave series sold well. Digital technology moves fast, however, and by the mid‑1980s, synths like the Yamaha DX7, Korg DW‑8000, and Sequential Prophet VS were offering the tempting delights of digital without the hefty price tag. PPG closed their doors in 1987.

At the same time, Waldorf Electronics GmbH, a new company created by PPG’s former German distributor, was forming. Wolfgang Palm worked with Waldorf to develop the integrated circuit chips for their first product, based on the PPG Wave. And so, in 1989, the Waldorf Microwave was released. Wavetable synthesis became Waldorf’s signature sound. The Microwave, Microwave II, Microwave XT, Wave, Blofeld, Largo, Nave, Quantum and Iridium all use wavetable synthesis, not to mention the various Eurorack modules Waldorf have released. Ask any synth fan to name a manufacturer of wavetable synths, and, more often than not, Waldorf will be the answer.

On a purely personal note, the Waldorf Microwave XT, a later version of the original Microwave, is one of my desert‑island synths. Even after 20 years of ownership, it still surprises me with sounds I could never imagine. It was with great excitement then that I received the Waldorf M for review.

What Is M?

The M is a modern recreation of the first Microwave, which has become a cult classic thanks to its combination of crunchy 8‑bit digital oscillators and smooth analogue filters. Subsequent revisions — the Microwave II and Microwave XT — moved to digital filters. Many felt they lacked the warmth of the OG. However, they did enhance sound design possibilities with a proper modulation matrix, lots of digital filter options, and enhancements to the synth engine like oscillator sync, ring modulation, FM and effects.

For better or worse, most of the Microwave II/XT improvements have not made it into the M. There are a couple of exceptions. Oscillators can work in Microwave I or Microwave II mode (more on that shortly), and sync and ring modulation are available (although only in the Microwave II oscillator mode). There is no FM, modulation matrix, or effects.

Like the Microwave, the M is an eight‑voice synthesizer. An optional voice expansion card will double the count to 16. It has two wavetable oscillators, a 24dB/oct filter (an SSI 2144 ladder design replaces the original Curtis SEM chip), analogue VCAs (stereo), four envelopes, and two LFOs. The M is also four‑part multitimbral (the OG was eight‑part, but with only eight voices; perhaps that was considered overkill).

You don’t have to look far to confirm that the M is more than just a reboot. The Microwave’s single‑knob 2U rackmount design wasn’t particularly fun to use, but the M’s spacious 440 x 305mm front panel offers plenty of hands‑on control. There’s a 3‑inch colour display and plenty of buttons to speed up navigation. Wavetable import, patch backup, and OS updates are all done via SD card. And along with the traditional MIDI DIN in, out, and thru ports, there’s a USB Type B port (for MIDI only, no audio).

The OG wavetables are all present and will sound pleasingly familiar to anyone who has ever owned a Wave, Microwave I, II or XT.

One welcome improvement is that each oscillator can now load a different wavetable instead of sharing one. Wavetables contain 64 waveforms, and there are 96 factory wavetables, plus an extra 32 slots for importing your own. The OG wavetables are all present and will sound pleasingly familiar to anyone who has ever owned a Wave, Microwave I, II or XT.

As I mentioned earlier, wavetables can work in one of two modes: MWI or MWII. These emulate the digital compression of either the Microwave I (8‑bit, 240kHz, no anti‑aliasing) or Microwave II (16‑bit, 40kHz, band‑limited). There was not as much difference in these modes as I had expected. High‑pitched sounds will exhibit different aliasing characteristics, and the 8‑bit mode does imbue some extra crunchiness on bass sounds, which is very welcome. But I doubt you would spot the difference when the synth is buried in a mix.

In MWI mode, you can even enable ‘ASIC bug mode’, which emulates a bug in the Microwave I that causes distortion if oscillator levels are above a certain threshold. This attention to detail is vital because the M is compatible with Microwave I SysEx files — great news for anyone with a sound library they want to migrate forward.