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Oberheim Xpander

Xpander
Oberheim Xpander.jpg
Oberheim Xpander
Manufacturer Oberheim
Dates 1984 - 1988
Technical specifications
Polyphony 6
Timbrality 6
Oscillator 2 per voice
LFO 5 per voice
Synthesis type Subtractive, FM
Filter 1, 2, 3, 4 pole low pass
1, 2, 3 pole hi pass
bandpass
notch
phase shift
Attenuator 2 per voice
Storage memory 100 single patches
100 multi patches
Effects none
Input/output
Keyboard none
Left-hand control none
External control CV/Gate
MIDI
Cassette interface

The Oberheim Xpander is a desktop version of Oberheim Matrix-12 and was an analog synthesizer launched by Oberheim in 1984 and discontinued in 1988. It is essentially a keyboardless, six-voice version of the Oberheim OB-8 and Matrix-12 (released a year later, in 1985). Utilizing Oberheim's Matrix Modulation technology, the Xpander combined analog audio generation (VCOs, VCF and VCAs) with the flexibility of digital controls logic.

The Xpander "Owner's Manual, First Edition" describes the technology as this:

Each of the six voices of the Xpander is completely independent. That is to say, each could be configured to create a different timbre - this is accomplished via the multi-patch mode which will be described below.

Starting at waveform generation, each voice has two voltage controlled oscillators (VCOs). Each of which is capable of generating sawtooth, triangle, pulse or noise waveforms. Furthermore, the "duty cycle" of the pulse width can be modulated as well. Although perhaps better known for subtractive synthesis, the Xpander is also capable of frequency modulation (FM) synthesis by modulating VCO #1 with VCO #2.

Moving on from the VCOs, the signal then passes through a multi-mode voltage controlled filter (VCF). The available modes on the filter are:

From the filter, there are two sequential voltage controlled amplifiers (VCAs) through which the signal must pass. And finally the audio is delivered to a variety of outputs: mono, stereo and six independent outputs (corresponding to the six voices).

Of those analog audio components (VCOs, VCF and VCAs), each can be modulated by several different digital controls.


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