This oscillator has a wider bandwidth, lower aliasing resulting in a brighter sounding sawtooth/ramp waveform. This achieved by using a series of harmonically related sine waves to create the wave forms, and thus generally has zero aliasing allowing us to have a much higher definition oscillator. This also means we can do away with the smoothing needed for the Gibbs effect in the standard SynthEdit oscillator.
Compare the frequency spectrum of two sawtooth signals (shown below) with a fundamental frequency of 440 Hz. Although the harmonic output still ends at about 30kHz the decrease in output up to this point is more linear than the older oscillator which tails off quite rapidly above 10 kHz. Let’s face it 30kHz is pretty good as it’s still way above the range of human hearing (unless of course you’re a Vampire…)
It also has two phase modes: 1) Free-running (not phase locked) 2) Sync where the oscillator always starts at the 0° phase point of the cycle. Both these modes are dependent on how the Oscillator is connected.
Note: For the VCO/DCO modes to work correctly there must be a VCA with a MIDI gate source somewhere in the audio output chain.
Note: This does not affect Phase Modulation, which works as normal in both modes.
Plugs.
Left Hand Side:
-> Pitch:- (Voltage) Controls the oscillator frequency this can be set to 1 volt per octave, or 1 volt per kHz in properties.
-> Pulse Width:- (Voltage) Width of the rectangular pulse waveform. The default control range is from -10 Volts to +10 Volts. 0 Volts = 50% width
-> Waveform:- (List) Selects different from waveforms; Sine, Saw, Ramp, Triangle, White Noise, Pink Noise.
-> Sync:- (Voltage) Applying an external oscillator to this plug Syncs the Oscillator to the external signal, produce a gnarly sound (works best with a pulse waveform)
-> Phase Mod:- (Voltage) Varies the phase of the output audio (default range -5 Volts to +5 Volts), can be used for Casio/Yamaha style “FM” sounds.
-> Disable:- (Boolean) Turns the oscillator on when “true”
-> Reset Mode:- (List) Select between; VCO (Freerun), and DCO (Sync).
The VCO (Freerun) mode means the oscillator will start at no fixed point on the waveform, whereas the DCO (Sync) always starts at the same point on the cycle.
Right Hand Side:
-> Audio Out:- (Voltage) Signal Output -10 Volts to +10 Volts.
Parameters:
♦ Frequency Scale:- Choose between 1 volt/Octave, or 1 volt kHz.
There’s no PM depth control?? No you need to control this separately. It’s not built in to the HD Oscillator.
Reset Mode-Free-run mode examples.
You can use the HD Oscillator in two free-run modes:
1) By using it as a “free running” Oscillator, this means it starts at a different point on the waveform every-time a new note is triggered, as long as you leave the Sync pin unconnected. This is a bit similar to a “drifting” analogue oscillator of a vintage hardware synthesizer.
Note: if you use multiple oscillators, they all will cycle the same so you doesn’t hear any difference when listening to them if the oscillators all have the same Phase Mod value set. You will hear a difference if you set different Phase Mod values for every single oscillator or you will notice a “drifting” effect if you sync one oscillator to the MIDI-CV Gate and leave the sync plugs of the other oscillators unconnected if they both have the same Phase Mod value set.
The connection mode in operation is shown below, and as you can see the two signals are out of phase, and will be in a different phase each time a new note is triggered.
2) The other option is connecting a MIDI-CV Gate to the Sync plug of all your oscillators, which ensures they all always will start from their pre-set Phase Mod value whenever a new note is received.
When setting the Phase Mod of an OSC to 0, then it always will start from Zero Phase.
Supersaw “mode”.
There is a third way for a special kind of oscillator, when using multiple oscillators to create a super-saw oscillator setup. That is to connect the Gate of the MIDI-CV2 module
to each oscillator, then feed each phase plug with a random voltage which is generated each time a new is triggered. This ensures that the oscillators will all start at different phase points on the sawtooth waveform each time a new note is triggered.
Of course for a true Super Saw or Unison sound we would have more oscillators, and in the case of a Super Saw you’ll also have small frequency offsets too. But the principle remains the same.
DCO Sync mode:
If the oscillator(s) are in DCO (Sync) mode then the waveform will always start in phase.
Even with multiple notes played you can see each sawtooth starts at the same phase of its cycle. They are synced to each other.
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