This adjusts the tuning of VCO1 (Voltage Controlled Oscillator 1) across a range of four octaves. The outer ring of the knob controls coarse tuning and the inner part of the knob controls fine tuning. Like the original hardware SEM, the coarse tune is continuous and there are no incremental steps when changing pitch. This is great for creating subtle pitch settings or variations, especially when creating differences between each SEM VCO.
However, for speed, we’ve enabled quantised incremental pitch changes to the coarse tune via a Right-Click (or Control-Click). Using this method you can quickly establish the desired pitch via the outer coarse tune ring, before using the inner fine tune ring for those subtle detunes.
When the MOD1 Knob is in its vertical position no modulation is applied to VCO1.
Moving the MOD1 Knob to the left modulates the frequency (pitch) of VCO1 using the modulation source set via the switch below it. The sources are as follows:
| ENV1 | The shape of Envelope 1 modulates the frequency (pitch) of VCO1 |
|---|---|
| VCO3 | The settings of VCO3 modulate the frequency (pitch) of VCO1 |
| LFO1 | The settings of LFO1 modulate the frequency (pitch) of VCO1 |
Provided PULSE is the selected waveform for VCO1, moving the MOD1 Knob to the right modulates the Pulse Width of VCO1 using the modulation source set via the switch below it. The sources are as follows:
| ENV1 | The shape of Envelope 1 modulates the Pulse Width of VCO1 |
|---|---|
| VCO3 | The settings of VCO3 modulate the Pulse Width of VCO1 |
| LFO1 | The settings of LFO1 modulate the Pulse Width of VCO1 |
<aside> ⚠️ The PULSE WIDTH Knob is only active if the PULSE wave is selected for VCO1 (in the VCF section). If the SAW wave is selected you will hear no changes when moving this knob.
</aside>
The PULSE WIDTH Knob manually controls the Pulse Width of VCO1.
In the vertical position the Pulse produced in each cycle is exactly one half as long as the cycle itself (i.e. 50%). This is known as a Square Wave. As the knob is rotated to the left of the vertical position the Pulse becomes narrower. As it is rotated right of the vertical the Pulse becomes wider.
Use this knob in conjunction with the VCO1 MOD1 Knob to vary the Pulse Width creating interesting, non-static waveforms.
When this switch is turned ON, VCO2 is synchronised to the frequency of VCO1. VCO1 is not affected but VCO2 only produces harmonics of the frequency to which VCO1 is set.
With the SYNC Switch in the left (off) position VCO1 & 2 run independently.