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"Architecture and featuresOscillators and Sound Generators
Each of the 12 voices has 2 Oscillators. Each Oscillator has sawtooth, triangle and square/pulse waves, mixable in variable proportions.
In Oscillator 1, each waveform can be modified: saw's "spread" parameter adds a second detuned sawtooth, triangle "wrap" progressively clips the waveform adding inharmonic content, and pulse wave has variable pulse width; PWM is also available, and the modulation source can be chosen from LFO1, LFO2 or OSC ENV. Oscillator 2 can frequency-modulate (FM) Oscillator 1.In Oscillator 2, saw and triangle waveforms cannot be modified/ modulated: only the pulse wave can be varied; PWM is also available. Unlike OSC1, the second oscillator provides fine detune and coarse detune +-24 steps, and keyboard tracking may be disengaged. Oscillator 2 can be synced to Oscillator 1.
An Oscillator Common section is provided to balance the mix of OSC1 and OSC2, the ring modulator and the noise generator.
Multimode Dual Filter
The OB•12 has two VCF, each one being a 12db (2 pole) filter.
For each filter, mode can be chosen between high-pass, low pass, band-pass and off.
Filters routing can be parallel, split or serial, the latter resulting in a 24db (4 pole) filter.
Cutoff, resonance, modulators and keyboard tracking affect both VCFs.
The Delta parameter, available in parallel and split mode, change the cutoff frequency of the second filter; by using bandpass mode for both filters and by widening their cutoff frequencies, two formants peak may be formed, creating vocal-like timbres.
Besides the OB•12, 1983's OSC OSCar synthesizer is the only synth having this facility; in the OSCar this function is called "separation" and has a dedicated knob in the filter section, unlike the OB•12, whose Delta parameter is inside filter's edit menu.








































