Tom Oberheim - SEM Pro


An analog classic from the 70s, but with patch connectors and MIDI – Originally, Tom Oberheim’s SEM was intended to be a backup synthesizer for layer sounds only. However, due to its cozy and fat sound, it quickly became a favorite among musicians. To this day, the instrument has lost none of its charm. It still can be heard regularly in music productions. The SEM’s signal flow consists of two oscillators, a multimode filter and a VCA. Furthermore, there are two envelopes and a LFO. Additionally, the Pro model features a well-equipped MIDI-CV converter and 21 analog patch points. The wonderfully warm, voluminous sound has not changed compared to the original version from 1974.


The SEM features a fully analog, discrete synthesizer voice. In detail, the instrument comes equipped with the following components:

  • Two full sounding oscillators
    • Sawtooth and variably wide pulse waves
    • Coarse and fine tune potentiometers
    • Frequency and pulse width can be modulated (The intensity is adjustable)
      Modulation sources: First envelope (VCO 1) respectively second envelope (VCO 2), LFO or external signal
    • Very musical sync function

  • Buttery soft, enormously fat multimode filter
    • Input mixer with channels for VCO 1, VCO 2 and external audio material
    • Filter type can be crossfaded between low-pass, notch and high-pass characteristic. Additionally, a band-pass mode is available.
    • Edge steepness: -12 dB per octave
    • Cutoff and resonance potentiometers
    • Cutoff modulation channel with variable intensity and polarity
    • Modulation sources: Second envelope, LFO or external signal

  • Two envelopes
    • Attack, decay and sustain potentiometers
    • The decay knob also determines the length of the release phase
    • One envelope is hard-wired to the VCA

  • Triangle LFO with adjustable frequency

Furthermore, the Pro model offers the following features:

  • MIDI CV converter
    • Selectable MIDI channel, controller number and pitch bend range
    • Note priority can be set to low, high or last
    • Retrigger, filter tracking and LFO reset options
    • Independent control bus allows velocity, controller data or channel pressure to modulate either or both VCOs, the filter frequency and the VCA
    • Transpose option (-2 octaves to +2 octaves)
  • Analog portamento function
  • Preamp for external audio material
  • 440 Hz tuner signal
  • 21 analog patch connectors (3.5 mm format)
2.4 kg
Article Number

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