GEM S2/R Turbo Music Processor Synth

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GEM S2/R Turbo Music Processor Synth

December 28, 2020 | | No Comments


When GEM released the S2 Music Processor in 1992, the synth world stood up and listened to the impressive technological rich and resonant sounds which the S Series produced.

Together with the many advanced features, functions, powerful sequencer, editing suite, ability to read and edit samples and excellent real-time controllers, the new S Series certainly stood out.

In 1993, GEM upgraded the S-Series with the a ‘Turbo Kit’ which allowed for many new and exciting functions and doubled the polyphony to 32 notes. The Turbo kit was also sold separately as an upgrade for the original S2 and S2 models.

The GEM S2/R is based on the excellent features found on the GEM S2 Turbo and is rack mountable.

On the matt black front panel, there are seven programmable sliders, seven programmable buttons and Pitch and Modulation wheels. All functions are logically and clearly displayed on a large graphical LCD with light blue neon back-lighting.

Due to the vast range of functions available and also thanks to two MIDI I/O’s, the GEM S2/R is an ideal master MIDI Expander Module for the home or professional studio.

The factory SRAM capacity is 512 Kb and can be expanded up to 2Mb, using part example 4 x UPD431000

Issues: The original (non-turbo), S Series models have a CR2032 lithium coin cell that backs up the global parameters (sounds, patches, and performances are not backed up but can be saved to disk). The GEM S2 Turbo, GEM S3 Turbo and GEM S2/R have SRAM for internal storage. The SRAM (Static RAM), uses a rechargeable NiCd backup battery which is prone to leaking and the battery acid when leaking, often corrodes the PCB and components.  Recommend changing the NiCd battery immediately for a separate battery pack, mounted away from the PCBs.

Upgrades: The Operating System (Firmware), is stored in EPROM (erasable programmable read-only memory).  Various releases were made and can updated to the latest (at the time).  The EPROM releases can be found in GEM & LEM EPROM Information and all EPROM BIN files can be found in the GEMClub Members Downloads area.

Disks: A large range of GEM and GEMClub members disks can be found in the GEMClub Members Downloads area.


  • SRAM Battery Backed (RAM Disk 512Kb)
  • SRAM Battery Backed (RAM Disk 2Mb)
  • SCSI Interface (not implemented)

Basic Overview:

  • Polyphony – 32 voices
  • Multitimbral – 16 parts
  • Sampler – 2 MB sample RAM (Volatile)
  • Oscillators – One or two per voice
  • Waveforms – 209 multisamples on 6MB ROM
  • Display: 240 x 64 pixel LCD, illuminated
  • LFO – 1 LFO with Sine, Triangle, Saw, Square, Random and S&H shapes
  • Filter – 2 DCF’s per voice 12 dB/Oct. with resonance (Lowpass, Highpass, Bandpass, Parameter Cut, Parameter Boost), with envelope.
  • Sound processing: subtractive synthesis, two 12 db filters with different characteristics and resonance, seven faders, poly pressure on filters and various controllers, complex modulation options
  • Envelope – 10-segment envelope with cycling
  • Effects – 2 units with reverbs, choruses, flangers, delays, rotary speaker simulation
  • Sequencer – 16-Track sequencer, up to 250 000 events/notes
  • Songs – 10 songs with 10 sequences each
  • Memory – 100 Performances
  • RAM / ROM memory: six Mb ROM, two Mb sample RAM
  • Mass storage: 3.5 “HD floppy
  • Special features: open operating system; Multitasking allows several operations at the same time (including load-while-play); two separate MIDI ins and outs
  • Control – 2 complete MIDI interfaces
  • Connections:
    • Two MIDI In / Out / Thru,
    • Volume pedal, two configurable button / pedal connections
    • Audio: stereo out, four individual outputs or two stereo groups


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Dave Williams

Original and sole proprietor of GEMWorks Europe, later renamed to GEMClub - Generalmusic Owners Club.

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