OBERHEIM XPANDER - The Analog Synthesizer That Was Ahead of Its Time

The Oberheim Xpander is a six-voice analog synthesizer, introduced in 1984 and produced until 1988. This instrument provided unprecedented flexibility thanks to its Matrix Modulation system, which allowed any modulation source to be connected to any target.

The Xpander was designed as a desktop version of the legendary Oberheim Matrix-12, retaining its complex sound architecture while offering a more compact design without a keyboard.

Technological Innovations – What Makes the Xpander Unique?

The Xpander introduced several key innovations that set it apart from other analog synthesizers of its time:

•  Two VCOs per voice – Each voice had two oscillators generating sawtooth, triangle, pulse, and
   noise.
•  Multimode filter – Offered 15 different modes, including low-pass, high-pass, band-pass,
   notch, and phase shift.
•  Five LFOs per voice – Each LFO had six different waveform types, including random and
   sample & hold.
•  Five envelope generators per voice – Each envelope generator had a DADSR structure
   (Delay, Attack, Decay, Sustain, Release).
•  CV/Gate inputs – Allowed integration with modular systems and older analog synthesizers.
•  Individual outputs for each voice – Enabled separate processing of each voice in a mix.

Sound Architecture and Flexibility

The Xpander was one of the most flexible non-modular analog synthesizers ever produced. Each voice could be configured independently, allowing:

•  Multitimbral mode – Each voice could have a different sound, enabling polyphonic layering or
   separate monophonic synthesizers.
•  Complex modulation options – Thanks to the Matrix Modulation system, any modulation source
   could be connected to any target.
•  FM synthesis – Allowed frequency modulation between oscillators.
•  Tracking generators – Provided non-linear modulation, adding an experimental character to
   the sound.

Curtis Filter – The Core of the Oberheim Xpander

One of the most significant features of the Oberheim Xpander is its multimode analog filter, which employs Curtis chips for dynamic and flexible sound shaping. Thanks to its wide range of filtering modes, the Xpander became one of the most versatile analog synthesizers of its time.

Filter Technology in the Xpander

The Xpander includes a voltage-controlled filter (VCF) with 15 different modes, including low-pass, high-pass, band-pass, notch, and phase shift. Each mode alters how the filter affects the sound, allowing for subtle or extremely aggressive tonal shaping.

Key characteristics of the Xpander’s filter include:

•  Smooth modulation of filter frequency via LFOs or envelopes.
•  Frequency modulation of the filter by an oscillator, enabling experimental FM-style effects.
•  Resonant saturation, enriching harmonic textures at higher resonance settings.
•  Tracking generators, allowing complex control over filtering curves without requiring an
   external modular system.

Sound Character of the Xpander’s Filter

The Xpander’s filter is known for its depth, precision, and flexibility, making it ideal for:

•  Deep analog bass lines, using its rich low-pass mode with strong resonance.
•  Aggressive synthetic leads, cutting sharply through a mix.
•  Cinematic ambient textures, with smooth frequency modulation creating evolving atmospheres.
•  Experimental sound design, where various filter combinations produce unique sonic effects.

The Filter as a Key Element of the Xpander

Thanks to its advanced filtering system, the Oberheim Xpander became an icon of analog synthesis, still inspiring sound designers today. The ability to combine multiple filtering modes, frequency modulation, and tracking generators grants musicians total control over their sound, making the Xpander one of the most flexible analog synthesizers in history.

Connectivity and Studio Integration

The Xpander was designed for easy integration into a studio setup. It featured:

•  MIDI interface – Full MIDI CC support for parameter automation.
•  CV/Gate inputs – Allowed connections with modular synthesizers.
•  Individual audio outputs – Each voice had a separate output, enabling independent
   processing in a mix.

How the Xpander Influenced the Development of Modern Synthesizers

Modular Flexibility Without Patch Cables

The Xpander was one of the first synthesizers to offer modular flexibility without requiring physical patching. Its Matrix Modulation system allowed any modulation source to be linked to any destination, a concept that has become standard in modern digital synthesizers.

Synthesizers inspired by the Xpander

•  Nord Lead – Provides complex modulation options similar to the Xpander, but in digital form.
•  Access Virus – Features a modulation matrix, enabling parameter routing similar to the Xpander.
•  Arturia MatrixBrute – A direct homage to the Xpander, offering modulation matrix routing
   without patch cables.

Multimode Filter as a Standard Feature

The Xpander was one of the first synthesizers to feature 15 different filter modes, including low-pass, high-pass, band-pass, notch, and phase shift. This concept inspired many modern synthesizers that now offer more than just a standard low-pass filter.

Synthesizers continuing this legacy

•  Sequential Prophet X – Features a multimode filter for extensive sound shaping.
•  Moog Subsequent 37 – While traditionally using a ladder filter, some Moog models have begun
   experimenting with multimode filters.
•  Elektron Analog Four – Includes a multimode filter, enabling creative sound design similar
   to the Xpander.

Advanced Envelopes and LFOs

The Xpander had five envelope generators per voice and five LFOs per voice, which was revolutionary at the time. Today, many modern synthesizers offer similar capabilities, inspired by the Xpander.

Synthesizers expanding upon this concept

•  ASM Hydrasynth – Offers complex envelopes and LFOs, enabling deep modulation.
•  Novation Peak – Features multiple envelopes and LFOs, allowing flexible sound shaping.
•  U-He Zebra – A software synthesizer offering extremely flexible modulation, clearly influenced
   by the Xpander.

Artists Who Have Used or Still Use the Oberheim Xpander

The Xpander has been a favorite instrument among musicians due to its flexibility and rich analog sound. Some well-known users include:

•  Jean-Michel Jarre – Used the Xpander for complex sequences and ambient layers.
•  Nine Inch Nails – Used the Xpander for experimental industrial textures.
•  Vince Clarke (Depeche Mode, Erasure) – Used the Xpander for synthetic bass lines.
•  Chemical Brothers – Utilized the Xpander for aggressive analog textures.
•  Orbital – Used the Xpander for cinematic atmospheric sounds.
•  Front 242 – Integrated the Xpander into electronic and industrial music.
•  Jan Hammer – Used the Xpander for film soundtracks.

Conclusion

The Oberheim Xpander is one of the most flexible analog synthesizers ever made. With its advanced modulation architecture, multitimbral capabilities, and extensive connectivity options, it has become an icon of analog synthesis.

Its rich sound, experimental possibilities, and seamless studio integration make it a timeless instrument, still sought after by musicians and producers today.