The Waldorf Microwave XT represents a pivotal evolution in wavetable synthesis, carrying forward the legacy of one of electronic music's most innovative technologies. To understand the XT, one must first look back at the groundbreaking work of Wolfgang Palm and his company PPG (Palm Products GmbH), whose Wave 2.x series in the early 1980s introduced the world to wavetable synthesis—a revolutionary approach that used digital wavetables containing multiple waveforms that could be scanned and interpolated in real-time.
By the late 1980s, PPG was fading as a company, but its technology would find new life through Waldorf Electronics GmbH. Founded in 1988 by Wolfgang Düren, who had been the German distributor for PPG, Waldorf was established in the German town of Waldorf near Bonn. The company's very name honored its German heritage, and its first product, the original Waldorf Microwave released in 1989, was essentially a rackmount evolution of the PPG Wave 2.3, even using the same wavetables and Curtis analog filters.
The original Microwave, while sonically powerful, suffered from a frustrating user interface with minimal hands-on control—just a few buttons and a single parameter knob that made sound design cumbersome without external editors. Waldorf addressed this limitation in 1993 with the release of the Waldorf Wave, a deluxe keyboard instrument with extensive control, but its high price point kept it out of reach for many musicians.
The digital revolution of the mid-1990s brought new possibilities, and in 1997 Waldorf released the Microwave II. This was a significant departure from the original: instead of analog filters, it employed a fully digital DSP-based architecture with digital filters. While some lamented the loss of analog warmth, the Microwave II offered improved wavetable capabilities, effects processing, and more compact 2U rackmount design.
The Microwave XT arrived in 1998 as the answer to years of user requests for hands-on control. Taking the Microwave II's sound engine and adding an unprecedented 44 continuous rotary encoders, the XT was instantly recognizable by its striking bright orange 5U rackmount chassis (a special black edition was also produced in limited quantities). This wasn't merely a cosmetic upgrade—those knobs provided direct, real-time access to virtually every major synthesis parameter: oscillators, wavetables, mixer, filters, amplifier, LFOs, modulation, and envelopes.
The XT improved upon the Microwave II with 20-bit D/A converters (up from 18-bit), adding extra headroom and clarity. The sound engine delivered 10-voice polyphony, expandable to 30 voices through optional expansion units. At its heart were two digital oscillators per voice capable of wavetable synthesis with 64 preset wavetables and 32 user-programmable slots, each containing 64 waves. The synthesis palette included oscillator sync, FM, ring modulation, and noise generation.
The filter section was particularly versatile for a digital instrument, offering 10 different digital filter models including 24dB and 12dB lowpass configurations, a Moog-style 24dB lowpass, sine waveshaper, FM filter, dual lowpass/bandpass, band stop, and more. Two LFOs with multiple waveforms (sine, triangle, square, random, sample and hold) and MIDI clock sync provided modulation possibilities, while four envelope generators—including a unique 8-level wave envelope with looping capabilities—allowed for complex sound shaping.
Following the XT's success, Waldorf released the XTk in 1999, adding a 49-key velocity and aftertouch-sensitive keyboard with a redesigned panel layout and wooden end cheeks. This made the wavetable synthesis engine truly portable and performance-friendly.
The Microwave XT and XTk found their way into the rigs of numerous notable artists. Electronic music acts like The Crystal Method and Astral Projection embraced its digital textures, while producer Mirwais (known for his work with Madonna) utilized its unique sonic character. The synthesizer's ability to create everything from warm analog-emulating basses to otherworldly evolving pads made it versatile across genres.
Unfortunately, Waldorf's success with the Microwave series couldn't prevent broader financial difficulties. On February 5, 2004, the company declared insolvency in German court. A new company, Waldorf Music GmbH, was established in 2006, though it was not a legal successor to the original entity. The new Waldorf, now headquartered in Remagen under CEO Joachim Flor, continues to develop synthesizers including the modern M wavetable synthesizer that pays homage to the Microwave legacy.
Today, the Microwave XT remains a sought-after instrument on the used market, prized for its unique combination of wavetable synthesis depth and hands-on programmability. Its distinctive orange appearance makes it instantly recognizable, while its sound—capable of both glassy digital textures and surprisingly warm analog-like tones—continues to inspire electronic musicians and sound designers decades after its release.