Coming Soon, Son Of 4 Voice Polyphonic Synthesizer!     See Below


SEM-PRO combines MIDI to CV with patchpanel. (Click for big picture.)


SEM with analog patchpanel.
(Click for big picture.)


SEM with MIDI to CV Converter.
(Click for big picture.)


Click to see my talk at the at the recent Red Bull Music Academy in Boston.


Welcome to my new website! Yes, it's true: I am back in the synth business and to start out I have reissued my very first analog synth-- the Synthesizer Expander Module (SEM). This new SEM module is pretty much the same as the original, that is to say 100% analog! True voltage controlled oscillators, the classic SEM multi-mode filter, analog VCA, analog envelope generators and LFO. Did I say it is 100% analog? In fact, I made the circuitry as close to the original as possible.

This initial release of the new SEM consists of three versions:

1) NEW! SEM-PRO. SEM with MIDI to CV Converter and integrated Patchpanel. This version combines the features of the MIDI to CV version (see below) with a 21-jack patchpanel and is personally autographed by me. The U.S. price is $1199.

2) SEM with Patchpanel. All internal SEM connections are brought out to 3.5mm minijacks - all 33 of them. The basic connections are a one-volt-per-octave VCO control voltage and a standard 0 to +5 volt gate signal. On this version of the SEM, there is no MIDI input. The U.S. price is $899.

3) SEM with MIDI to CV Converter. This version includes a high precision MIDI to CV Converter that has been specifically designed to allow MIDI to control the SEM, and has additional features that make use of the SEM's external inputs. Some of the features of the MIDI to CV Converter are:

  • Select MIDI channel, controller number and bend range

  • Select note assignment modes: latest, high note and low note priorities

  • Select note re-trigger, filter track, LFO reset

  • A second independent control bus allows velocity, controller data, or channel pressure to modulate either or both VCOs, the filter and the VCA

  • Transpose function allows different keyboard controllers to utilize the complete MIDI note range

  • Analog portamento

  • Input preamp gain control - allows an external audio input to be processed thru the SEM

  • High precision A-440 Hz tune signal

  • Control voltages and gate are bought out to rear panel connectors so MIDI to CV function can be used with other CV/Gate gear.

The U. S. price is $899.

In addition the basic SEM module with no case, power supply or supplemental module is available specifically for drop-in replacement for an original SEM in older Oberheim polyphonic systems. The U. S. price is $599. (special order)

Coming Soon!
SO4V unit at right,
Programmer Panel, above.
(Click for big pictures.)



Son Of 4 Voice Polyphonic Synthesizer: "SO4V"

  • Four classic Synthesizer Expander Module (SEM) synth modules
  • SEMs are 100% discrete analog - no custom chips
  • New state of the art Voice Control & Programmer retains all features of the original Four Voice Programmer and Keyboard control modules while adding new capabilities
  • SO4V may be used as a four-voice polyphonic synthesizer or as four individual synthesizers under MIDI control
  • Two MIDI sync capable LFOs with multiple waveshapes including sample and hold per voice
  • Two programmable ADSR envelope generators per voice
  • Selectable master tuning (both VCOs or VCO2 only) allows easy detuning for huge unison sounds
  • Polyphonic portamento with linear or exponential response
  • Noise generator connected to filter input #1
  • External audio or A440 tuning reference connected to filter input #2
  • Updated output module with mix and pan control for each voice
  • Two SO4Vs can be easily connected together - result: eight voices!
  • Signature plate--each SO4V comes with Tom Oberheim's signature on the front

U.S. Price: $3495



The combination of the SEM's limited programmability, combined with programmable envelope generators and LFOs in the new Programmer, allows many but not all of the SO4V's parameters to be remembered in memory patch storage.

The most important parameters that remain non-programmable in the new Son Of 4 Voice are resonance, filter modes, and initial pulse width.

This was the same situation with the original 4-Voice, and while certain parameters remain non-programmable, enhanced features of the new Programmer add capabilities that the old 4 Voice did not have, programmable or not. Also, the patch storage in the new Programmer is four-way multitimbral, so you can have a different setup stored for each SEM in a patch.

There is also a complete MIDI implementation in the SO4V, including LFO sync to MIDI clock and individual MIDI access to each SEM voice. And the patch storage includes the settings on the enhanced Keyboard Electronics / Voice Assignment section.

The SO4V is a special machine - for ease of use and fast setup, it is outdone by numerous hardware and software synths conceived for the mainstream. But there is nothing on the planet that SOUNDS like it!







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Thanks for stopping by!

- Tom Oberheim