The Issue 5 Oakley Equinoxe Voltage Controller Phaser
The Oakley Equinoxe is a classic four stage OTA based phaser and designed to be similar in
sound to the phaser used by Jean Michel Jarre on the Oxygene and Equinoxe albums.
In its standard form the Oakley Equinoxe produces two deep notches in the frequency
response of the unit. These notches can be considered as band stop filters whereby a very
narrow portion of the sound's spectrum is filtered out. Since the standard Equinoxe has four
internal phase shifting stages two notches are produced.
The Equinoxe allows the frequency of all the phase shifting circuits to be controlled by an
external control voltage (CV). This allows envelope generators to be used to sweep the phaser
to create filter type effects. It also contains an inbuilt low frequency oscillator that is
connected internally to the phase shifter when a CV is not being applied.
The module has four pots:
Frequency:
This controls the frequency of the two notches created by the phase
shift network.
Emphasis:
This accentuates the feedback signal within the phaser to create a
deeper effect.
Modulation depth:
A simple attenuator to adjust the level of the internal LFO or incoming
CV. With no jack plug inserted into the CV IN socket the internal LFO
is controlled by this pot. When a jack plug is inserted into CV IN then
the LFO is automatically disconnected and the CV input takes over.
LFO rate:
Adjusts the speed of the LFO. A dual colour LED indicates the output
status.
The internal LFO produces a triangle wave output which is also available from a front panel
socket. This allows you to use the internal LFO for other modulation purposes. As stated
above the LFO signal is automatically routed to the modulation depth pot when no jack is
inserted in the CV input.
The LFO output can be configured as normal or inverted. In normal mode the LFO output is
simply a copy of the signal being sent to the phaser circuitry. That is the voltage output from
the LFO OUT socket rises as the phaser frequency moves upwards. In inverted mode the LFO
output is an inverted signal. Thus when the phaser is being swept upwards, the LFO OUT
signal is going downwards. The mode is selected by the position of a movable jumper found at
the lower edge of the circuit board. It is not expected that you will be changing the mode on
the fly. The LFO mode does not affect the polarity of any CV IN signal.
By having two Equinoxe modules you can use one to modulate the other. Simply connect the
LFO OUT of one (the master) to the CV IN of the other (the slave). You can now modulate
both phasers with the master's LFO. If the LFO mode is set to non inverting this will allow for
true stereo phasing, whereby both channels are treated equally. With mode set to invert then
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