The Waldorf Microwave II emerged from a rich legacy of German synthesizer innovation that began with PPG (Palm Products GmbH) in the early 1980s. PPG's Wave 2.x series, designed by Wolfgang Palm, pioneered wavetable synthesis—a technique where a sequence of different waveforms is scanned during the duration of a single note to create complex, evolving timbres. When PPG ceased operations in 1987, Waldorf Electronics GmbH, founded by Wolfgang Düren in 1988, acquired the technology and key personnel, becoming the torchbearer for wavetable synthesis.
The original Waldorf Microwave debuted in 1989 as a rackmount module that brought PPG Wave technology to a broader market. It combined digitally sampled wavetables (64 per table) with analog VCF and VCA sections designed around Curtis CEM filter chips, creating a unique hybrid sound that was both digital in its complexity and analog in its warmth. The Microwave I gained a devoted following but was limited by its sparse interface—a single data wheel and minimal buttons made deep editing challenging.
After eight years of the Microwave I's success, Waldorf released the Microwave II in 1997. The decision to update the instrument came as DSP technology had matured significantly, offering cleaner, more stable sound generation. However, this technological advancement came with a controversial trade-off: the Microwave II replaced the original's beloved analog filters with an all-digital architecture. While purists lamented the loss of analog warmth, the new DSP platform offered several advantages: increased polyphony from 8 to 10 voices, onboard effects processing, expanded memory (256 user patches and 128 performance multis), and improved MIDI implementation.
The Microwave II's synthesis engine was built around two oscillators per voice, each capable of drawing from 128 wavetables (64 factory, 32 user-programmable, and 32 reserved). The wavetable scanning technique remained true to the PPG legacy, allowing for dramatic timbral sweeps that became the instrument's signature sound. Additional features included oscillator sync, FM capabilities, a ring modulator, noise generator, and an innovative dual-filter architecture with multiple modes including 24dB and 12dB low-pass, band-pass, high-pass, and unique waveshaping options.
The user interface saw significant improvement with the addition of four continuous rotary knobs under the LCD display, enabling real-time performance control without menu diving. The 2-line x 40-character backlit LCD provided clearer feedback than the original. A programmable rhythmic arpeggiator with 16 patterns and MIDI clock sync added performance possibilities, while Multi mode allowed eight-part multitimbral operation with layering and splitting capabilities.
Despite its digital architecture, the Microwave II maintained the distinctive 'Waldorf sound' characterized by grungy, aggressive digital textures that could range from glassy pads to screaming leads. Sound designers particularly appreciated features like Aliasing control, which deliberately introduced digital artifacts for vintage character, and Time Quantization, which added 'fizziness' by overriding wave interpolation algorithms.
The Microwave II achieved commercial success and spawned the Microwave XT in 1998, which added 44 dedicated control knobs, external audio input, and delay effects in a striking orange 5U rack chassis. The XT addressed the primary criticism of the Microwave II—its lack of hands-on programming—while maintaining identical sound architecture. Later, the XTk keyboard version provided a 76-key master keyboard option.
Notable users of the Microwave series have included Nine Inch Nails, who featured the instrument heavily in their studio productions; electronic music pioneers like Hardfloor and Crystal Distortion who exploited its aggressive digital character; film composer Vangelis who used its evolving textures; and artists like Jimmy Edgar who explored its sonic extremes.
Production of the Microwave II continued alongside its XT variant until Waldorf's original company declared insolvency in 2004. A new Waldorf Music GmbH emerged in 2006, but the Microwave II/XT line was discontinued, becoming sought-after vintage instruments. Today, the Microwave II is recognized as a significant evolution in wavetable synthesis—a bridge between the analog-digital hybrid era and modern DSP-based instruments, maintaining the unique sonic DNA established by Wolfgang Palm's original PPG designs while pushing the technology forward.