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RSF | Kobol Expander


The rack version came in four different components.

The Kobol Rack (Expander I) was essentially only the VCO/VCF/VCA/LFO sections of the Kobol in a rack module.  It features 2 VCOs with sweepable, waveforms, 2 ADS envelopes, an LFO, a VCF,Noise Generator, reversible voltage processoer, decay on/off, a self-oscillating 24db low pass filter, and 1 volt Ocatve CV/Gate inputs.

The Expander 2 was an add-on to the Kobol that added some new processing modules. The 19" 3 U space unit features a Ring Modulator, Envelope, a VCA, an LFO, Mixer with 3 inputs and 1 output. Additionally it has a Sample & Hold module with internal or external clock, a Noise Generator, Voltage processor that is delectable Linear or Logarithmic, Voltage Inverter, Gate Delay, an Envelope Follower, Lag Generator, and finally 2 multiples.

The Programmer rack module contained the memory circuits for storing patches and sequencing.

And the KM8 was an 8-channel rack-mount mixer.

The connections between modules were normalized but could be bypassed by external patches, similar to other semi-modulars like the ARP 2600 and Korg MS-20.

ModelKobol Expander
Engine TypeAnalog
Voices (max)1
LFO1 LFO, triangle, square waveforms, rate knob
Engine Detailed2 VCO's; triangle, square, saw, pulse; variable sweep
Filter (VCF)1VCF 24db low pass
Envelope (VCA)2 ADS envelopes
Key typeN/A
CV-gateCV/Gate 1 volt / octave
Produced:1979 - 1979
Legend: Obvious Y: Yes, N: No, N/A: Not Applicable
VCO Voltage Controlled Oscillator DCO Digital Controlled Oscillator
LFO Low Frequency Oscillator Sub Sub Oscillator
VCF Voltage Controlled Filter VCA Voltage Controlled Amplifier
Velocity As with a piano, the harder you hit a key, the louder the sound, unlike most organs which always produce the same loudness no matter how hard you hit a key. Aftertouch Pressing a key after you activated it. Channel Aftertouch, no matter which key, it will send a Channel message. Poly Aftertouch, sends the pressure per key instead of the whole channel.
Values for OSC, LFO, Filter, Envelope are per voice unless stated otherwise.

Manuals, patches etc.


If you like to discuss or talk about synths in all forms (including VST and modular), you are welcome to join the Facebook group "The Hard, The Soft and The Modular".

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