
The Behringer 2-XM is a faithful clone of the iconic Oberheim Two Voice from 1975. Technically, it combines the original 1974 SEM synthesizer with the later SEM patch panel, resulting in a streamlined but fully capable version of the classic. What defines all SEM synthesizers, regardless of era or number of voices, is the structure of the individual voices. The SEM is renowned for its extremely warm and smooth sound. Even at full resonance, it never becomes harsh or aggressive. This makes it ideal for pulsating basses, radiant leads, organic sync sounds and precise sequences. Behringer has preserved the character of the original while adding subtle enhancements. For example, the triple selector switch for oscillator modulation now includes E+V (envelope with velocity), and the same feature has been applied to the two VCAs. In the oscillator mixer, the EXT control now provides a noise generator instead of a second input for external signals. The 2-XM features dual voices, each fully equipped. A voice mixer is included, and portamento can be set independently per voice. By changing the form factor,

Each voice mirrors the historical SEM design with three minor updates. The analog signal path begins with two oscillators generating sawtooth or square waveforms with PWM, adjustable across five octaves. Oscillator two can be synced to oscillator one, and both pitch and pulse width can be modulated via envelope or LFO. The oscillator mixer determines which waveform is sent to the filter and at what level. The EXT control can feed an external audio source or a noise generator to the filter. The filter is a true state variable design, first introduced in 1974. In LP-HP mode, the control continuously morphs the filter from lowpass through notch to highpass. In BP mode, the control has no effect, but a rich bandpass filter processes the signal. The VCA completes the audio path. Two ADS (Attack/Decay/Sustain) envelopes and an LFO with a sine waveform modulate the voice. Except for the VCA, all modulation sources are pre-wired to the filter and oscillators, with ENV2 controlling the VCA.


On the right-hand side of the control panel there are 2x 16 CV, gate and audio inputs and outputs for each voice. If you patch e.g.

