> tech specs
VCO
* Triangle based VCO core
* manual tune control (with an internal jumper the range can be set to ~ +/-1 half an octave or ~ +/-2.5 octaves)
* range switch -1 / 0 / +1 octave
* frequency range about 10Hz ... 12kHz
* FM (frequency modulation) control with modulation source switch (LFO1 / off / ADSR)
* manual pulsewidth control for rectangle waveform
* PWM control with modulation source switch (LFO2 / off / ADSR)
* waveform switch (sawtooth / off / triangle)
* the sum of the waveform chosen by this switch and the rectangle is fed into the VCF (to turn the rectangle off the PW control has to be set fully CCW)
* external CV input for VCO frequency (1V/octave)
* external CV input for external PWM of the rectangle * internal CV input for frequency (1V/octave) connected to the CV1 output of the built-in USB/Midi interface

VCF
* 24 dB low pass
* ~ 12 octaves frequency range
* manual frequency control
* tracking switch half - off - full (internally connected to the external frequency CV input of the VCO, i.e. the VCF tracks to the VCO if the switch is set to "half" or "full" position)
* XM: exponential FM (frequency modulation) control with modulation source switch (LFO2 / off / ADSR)
* LM: linear FM (frequency modulation) control to modulate the VCF by the triangle of the VCO in a linear (!) manner
* manual resonance control (up to self oscillation)
* external audio input (this signal is added to the VCO signal)
* external CV input for filter frequency
* 1V/octave tracking for usage of the VCF as a sine wave oscillator over some octaves (not as precise as the VCO and not temperature compensated, but much better than most of the other filters)

VCA
* manual amplitude control (initial gain)
* AM (amplitude modulation) control with modulation source switch (LFO1 / off / ADSR)
* external CV input for VCA amplitude
* special control scale: exponential scale in the range from about -20dB to -80/90dB, linear scale from about -20dB to 0dB
Remark: this special control scale results in a loudness behaviour that is a bit different from pure linear or exponential VCAs
* "CV clipping feature": as the amplification of the VCA ranges from 0 to 1 only, each negative CV and each positive CV that corresponds to an amplification beyond 1 will cause kind of control voltage clipping

LFO1 and LFO2
* manual frequency control
* waveform switch (triangle / off / rectangle)
* range switch (low, audio, medium)
* LED display
* the LFO1 signal is available as an additional socket (to use the LFO1 signal for external modules)
* an internal jumper can be used to select between the LFO1 signal or the inverted LFO1 signal

ADSR
* manual controls for Attack, Decay, Sustain, Release
* range switch (long, short, medium)
* blue LED display
* ADSR signal is available as an additional socket (to use the ADSR signal for external modules)
* External Gate input (normalled via switching contact of the socket to the Gate output of the built-in USB/Midi interface)

USB/Midi-Interface

In/Outputs (all 3.5 mm jack sockets, except USB, Midi and power supply)
* front panel:
o CV In VCO frequency (1V/oct)
o CV In VCO pulsewidth (about 5V range for full scale)
o CV In VCF frequency (~ 1V/oct)
o CV In VCA amplitude (0...+5V)
o Gate In (0/+5...12V)
o External Audio In (typ. 1Vss without distortion)
o inverted LFO1 Out (~ -2.5 ... +2.5V)
o Envelope Out (~ 0 ... +6V)
o Audio Out (typ. 1Vss)
* rear panel:
o USB
o Midi In
o Learn button
o Gate Out (with LED for Gate display and learn function), 0/+5V