Quadrature VLFO

Quadrature VLFO is a very low-frequency oscillator that returns not just a basic signal, but also the three signals in successive phase quadrature relationships. In other words, if the basic signal is at 0 degrees phase, the four signals returned by the bottom four output jacks will be phase offset to 0, 90, 180, and 270 degrees, respectively. The LFO's frequency can be finely tuned over two button-selected ranges, the lower of which covers 3 hours (period) to 1 Hz, and the upper, 1 Hz to 30 Hz. The frequency can be phase-shifted by up to 360 degrees and FM modulated by scaled, externally-supplied signals. The LFO can be either manually- or CV-synchronized.

Given the wide frequency/period range the LFO handles, there are five different views of the data available, two in terms of frequency, and three in terms of period, the latter being easier to deal with when the frequency is very low. A display window always shows the setting either in units of the current viewing mode, or in Hertz, as desired. Each view specifies two units, one for the Coarse Frequency knob, the other for the coaxial Fine Frequency knob, i.e., "Hz/mHz".

The output waveform can be any of: sine, triangle, sawtooth, ramp, square, or pulse, with the last being pulse-width-modulatable. Outputs can cover either a one or five volt range, and can be any of: bipolar, unipolar positive, or unipolar negative.

A separate output jack supplies period-timed triggers, selectable from any of the four quadrature channels, or a mixture thereof. In addition, if you're willing to forgo the normal output of a channel, you can instead get that channel's associated trigger, giving you considerable timing capabilities.

The help you're currently reading is always available within the module by clicking on the Cyberwerks name at the bottom of the module; in Windows the four help screens can also be displayed by pressing h, ctrl-shift-h, ctrl-alt-h, and alt-h with the module selected; in MacOS the equivalents are F1, cmd-shift-F1, cmd-option-F1, and option-F1.

Controls

• The Coarse (bottom) and Fine (top) Frequency Knobs set the LFO's frequency (or period) in units determined by the currently-set view (see View Toggle). Changing the range or view changes the range and units of the Frequency Knobs appropriately. This will be reflected in the values and units shown in the display window, and in the dialogs associated with changing the knob values via the keyboard.

• The Phase Adjust Knob changes the base phase offset of all four output channels by up to 360 degrees.

• The Display Window shows the LFO's current frequency or period in the coarse units appropriate to the currently-set view. Clicking on the Display shows instead the equivalent in Hertz, in purple as a reminder; clicking again toggles it back.

• The Waveform Toggle cycles through the six different waveforms the LFO can generate.

• The Polarity Toggle cycles through, in order, bipolar, unipolar positive, and unipolar negative polarities for the output channels.

• The Output Voltage Toggle selects either the Voltage Modular standard of five Volts, or the EuroRack standard of one Volt for the output amplitude range.

• The Trigger Location Toggle sets triggers to be generated at the start of cycles in each channel (Tr SoC), or at the end (Tr EoC). To use the module as a timer, the latter is probably best.

• The Range Toggle switches between the High and Low frequency ranges; the former allows frequencies between 1 and 30 Hz, while the latter ranges between a period of up to three hours, and a frequency of 1 Hz. The period-based views (see View Toggle) are indispensible in dealing with the lower range. The module remembers the frequency that was set while in either range, returning to that value upon switching back; thus, there are two remembered frequencies, one for each range, a necessity, since the High and Low ranges only intersect at 1 Hz.

• The View Toggle switches among five different views of the frequency/period data, two of which are frequency-oriented, the other three period-oriented. The Coarse and Fine Frequency Knobs change to reflect the current setting of the View Toggle, as does the Display Window; the units shown on the toggle are in the form Coarse/Fine. The reason for this is to make it easier to work with very low frequency settings, and with units that might make more sense for your current situation. Changing the view does not change the frequency; just the way it's displayed and edited. (The Range Toggle does change frequency, as previously noted).

• The Sync In Jack and Sync Button reset the four channels to the appropriate start points in their cycles, the former by CV input (truth value on a rising edge, or trigger/gate), the latter manually.

• The Frequency CV Jack and Level Adjust Knob allow for frequency modulation, with the adjust knob scaling the CV input by up to 100% positive or negative.

• The Pulse CV jack and Level (L) and Offset (O) knobs allow the duty cycle of the Pulse waveform to be CV modulated. The Offset knob sets the base duty cycle (default: 50%) between 1% and 99%. When the jack is populated, the Level knob scales the input CV from zero to 100% (default: 25%) before adding it to the base cycle.

• The four small Trigger Select Toggles select the four channel triggers for summed output to the Trigger Out Jack.

• The four Channel Level Knobs scale the associated channel's output level over the range 0-100%.

• The Channel Trigger LEDs light to indicate that a trigger has just been generated on the associated channel.

• The small Channel Source/Trigger Toggles let you switch the channel outputs between sending the generated LFO waveform and the period trigger for the associated channel.

• The Channel Output Jacks are the main outputs for the four Quadrature VLFO waveforms.