VRG

Versatile Ramp Generator

The Oakley Versatile Ramp Generator (VRG) is a single width 5U high module that can function as a voltage controlled variable symmetry oscillator, a traditional attack-decay envelope generator, a one shot transient generator with patch programmed repeat, a voltage controlled slew generator, a gate delay and an audio filter. The output slope can be either linear or exponential.

The output signal will rise at a rate determined by the UP control and the up control voltage input. The output signal will fall at a rate determined by the DOWN control and the down control voltage input.An additional output is available called NEG OUT. This output is a gate style signal that is 0V when off and +5V when activated. It will be activated when the main output falls below 600mV. A bi-colour LED gives visual indication of the module's main output signal level. The various operating modes of the instrument are determined by the three way mode switch and use of the SLEW IN jack socket.

1. Slew generator

Inserting a jack into the SLEW IN socket activates the slew generator. The output of the module now attempts to follow the input signal. However, the rise and fall times are determined by the module's controls and CV inputs. Fast moving inputs are thus slewed at rates controlled by the VRG. You can use this mode for portamento effects, basic filtering and creating attack-release envelope shapes.

2. Variable symmetry low frequency oscillator

With no jack inserted into the slew in socket and the switch set to LFO, the VRG behaves as an oscillator. The waveshape and frequency are controlled by the up and down controls and their CV inputs.
•Maximum frequency: 600Hz - linear, 300Hz - exponential
•Minimum frequency: 0.009Hz (one cycle per two minutes) - linear, 0.003Hz (one cycle per 5 minutes) - exponential.
•Output level: +5V to -5V.

3. Traditional attack-decay envelope generator

The gate input allows the VRG to be triggered as you would an ordinary envelope generator. This makes it ideal for generating plucked sounds. A falling gate signal while the attack phase is ongoing will cause the output to fall back to zero at a rate determined by the decay controls.
•Attack time: 0.5ms to 30s (linear), 0.75ms to 50s (exponential)
•Decay time: 0.5ms to 30s (linear), 2.2ms to 3 minutes (exponential)
•Output level: 0V to +5V.

4. One shot transient generator

The gate input starts an attack-decay curve much like a traditional attack-decay envelope generator. However, the attack phase will always complete even if the gate is removed before it gets to the top of the cycle. This can create long lasting output signals that can be triggered from just momentary gates.
•Attack time: 0.5ms to 30s (linear), 0.75ms to 50s (exponential)
•Decay time: 0.5ms to 30s (linear), 2.2ms to 3 minutes (exponential)
•Output level: 0V to +5V.

The one shot can be triggered to cycle endlessly up and down by connecting a patch lead from the NEG OUT socket to the GATE socket. The NEG OUT can be also used as a gate delay in the one shot mode.
Price £175 GBP

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