VCO-S

Cwejman

Unlisted LFO Oscillator

Combined voltage controlled oscillator and sub oscillator

The VCO-S consist of 3 main blocks:

1) Main oscillator (C2) works in audio/LFO mode and has seven waveforms (very similar to VCO-6) with detuned saw and two different pulses (see below).
2) Suboscillator (C1) frequency is one octave down including all waveforms.
3) Dual LFO with triangle and square outputs (not attenuated) and triangle is pre-patched (attenuable) to PWM inputs for C1 (by LFO1) and C2 oscillators (by LFO2). Both LFO rates can be voltage controlled, as well.

Frequency Controllers

The main oscillator's frequency is controlled by RANGE (from C2 to C8 for main oscillator and form C1 to C7 for sub oscillator), TUNE knob (± 6 semitones in audio mode and ± 12 semitones in LFO mode), and leveled FM inputs (DC coupled FM2 and exponential F1 and FM3). Frequency modulation (leveled FM1, FM2, and direct FM3) determines the intensity of frequency modulation and/or pitch control.

Waveforms (both main- and sub-oscillators)

The VCO-S is equipped with seven switchable waveforms:

1) Sine contains low order harmonics (1% max THD)
2) Triangle contains more high order overtones than sine and sounds still "dull" and "pure" but with more "edge"
3) ?
4) Saw contains many overtones and sounds "rich" and "cutting"

The VCO-S also has three different pulse-controlled and modulated waveforms:

5) Width-modulated sawtooth, which acts as a true detuned dual sawtooth oscillator. Detuning controls by the pre-patched LFO1 (main oscillator) and by the pre- patched LFO2 (sub oscillator). Detuning (or saw pulse width) can be controlled by external signals (PW MOD CV), as well. The true detuning effect requires a triangle 5 Volts peak-to peak signal. LFOs frequencies can controlled manually (knobs) and/or by external signal so the above described detuning effect can be done more natural by "speed up" LFOs frequencies along the musical scale (just as two separate detuned oscillators). A very rich and "fat" sound (four different tones) is possible by applying different frequency to main- and sub oscillators pulse modulated saw. The VCO-6 has two different sounding pulses:
6/7) Pulse 1 and Pulse 2. On the main oscillator, both pulse widths are controlled by the pre-patched LFO1 and/or by an external signal coupled to the PW MOD CV (C1/LFO1). On the sub oscillator, both pulses are width controlled by the pre-patched LFO2 and/or by an external signal coupled to the PW MOD CV (C2/LFO2). The manual controllers for the LFO1 and LFO2 (LEVEL1 and LEVEL2) are coupled to the pulse width for the main and sub oscillator.

SYNC means that the oscillator frequency is tracked to the frequency of the controlling oscillator.

Total frequency range controlled by manual controllers and FM signals: 0.01Hz to 22kHz, including LFO mode

Controls:

RANGE:
Switch between audio (high) and LFO (low) frequency ranges

MAIN OSCILLATOR:
32 Hz to 2 kHz (C2 to C8) in seven steps, 0.2 Hz to 12 Hz in LFO mode
12 semitones (AUDIO mode), 24 semitones (LFO mode)

SUB OSCILLATOR:
16Hz to 1kHz (C1 to C7) in seven steps, 0.1Hz to 6Hz in LFO mode
12 semitones (AUDIO mode), 24 semitones (LFO mode)

WAVEFORMS:
Pure sine (1% THD)
Triangle
?
Sawtooth
Pulse-modulated Sawtooth
Pulse 1
Pulse 2
All waveforms 10 Volts peak to peak

FM1:
Exponential FM, leveled form 0 to 1 Volt/octave

FM2:
Linear FM, leveled, DC or AC coupled

FM3:
Exponential FM, unleveled 1 Volt/octave

LFO1 & LFO2 RATE:
0.1Hz to 200Hz, manual and by control votages (RATE1 and RATE2)

OUTPUTS:
Triangle and square, 10 Volts peak to peak, for each LFO
Sub C1 and osc C2