Oakley Equinoxe User manual

Oakley Sound Systems
5U Oakley Modular Series
Equinoxe
Voltage Controlled Phaser
PCB Issue 5
User Manual
V5.
Tony Allgood
Oakley Sound Systems
CARLISLE
United Kingdom

The standard front panel design for the 1U wide MOTM format module.
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Introduction
This is the User Manual or the issue 5 Equinoxe 5U module rom Oakley Sound. This
document contains an overview o the operation o the unit and all the calibration procedures.
For the Builder's Guide which contains in ormation on how to construct the module rom our
PCB and parts kits please visit the main project webpage at:
http://www.oakleysound.com/equinox.htm
For general in ormation regarding where to get parts and suggested part numbers please see
our use ul Parts Guide at the project webpage or http://www.oakleysound.com/parts.pd .
For general in ormation on how to build our modules, including circuit board population,
mounting ront panel components and making up board interconnects please see our generic
Construction Guide at the project webpage or http://www.oakleysound.com/construct.pd .
The standard Equinoxe module fitted into a black finish Schaeffer panel.
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The Issue 5 Oakley Equinoxe Voltage Controller Phaser
The Oakley Equinoxe is a classic our 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 orm the Oakley Equinoxe produces two deep notches in the requency
response o the unit. These notches can be considered as band stop ilters whereby a very
narrow portion o the sound's spectrum is iltered out. Since the standard Equinoxe has our
internal phase shi ting stages two notches are produced.
The Equinoxe allows the requency o all the phase shi ting circuits to be controlled by an
external control voltage (CV). This allows envelope generators to be used to sweep the phaser
to create ilter type e ects. It also contains an inbuilt low requency oscillator that is
connected internally to the phase shi ter when a CV is not being applied.
The module has our pots:
Frequency: This controls the requency o the two notches created by the phase
shi t network.
Emphasis: This accentuates the eedback signal within the phaser to create a
deeper e ect.
Modulation depth: A simple attenuator to adjust the level o 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 o the LFO. A dual colour LED indicates the output
status.
The internal LFO produces a triangle wave output which is also available rom a ront panel
socket. This allows you to use the internal LFO or 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 con igured as normal or inverted. In normal mode the LFO output is
simply a copy o the signal being sent to the phaser circuitry. That is the voltage output rom
the LFO OUT socket rises as the phaser requency 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 o a movable jumper ound at
the lower edge o the circuit board. It is not expected that you will be changing the mode on
the ly. The LFO mode does not a ect the polarity o any CV IN signal.
By having two Equinoxe modules you can use one to modulate the other. Simply connect the
LFO OUT o one (the master) to the CV IN o the other (the slave). You can now modulate
both phasers with the master's LFO. I the LFO mode is set to non inverting this will allow or
true stereo phasing, whereby both channels are treated equally. With mode set to invert then
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you will create a orm o stereo phase panning, where each phaser moves in an opposite
direction to give a wide stereo e ect.
The unit is designed to work with standard MOTM/Oakley signal levels, although it is possible
to modi y your unit to be run straight rom a guitar.
Power (+/-15V) is provided to the board either by our standard Oakley 4-way header or
Synthesizers.com header. Current draw is around 30mA. This unit will also run rom a +/-12V
supply with a slight reduction in dynamic range.
The Oakley Equinoxe is also available in a small modular ormat as the Analogue Systems
RS400.
ere we can see the three pin header and two way jumper that selects the LFO mode. In the position
shown in the photograph the LFO OUT will produce an inverted signal - the jumper is aligned with the
letters INV on the circuit board.
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Issue History
Issue 1 was the irst version and is easily identi iable by its use o the green plastic Omeg E16
pots. During 2003 it was reported that some Omeg pots were ailing in the ield and, indeed,
some had even been supplied to us rom the actory as aulty. During that year we completely
revamped the whole Oakley modular range to use a more reliable and expensive part.
The new issue 2 PCBs were made to support Spectrol/Vishay 248 pots and used our specially
made and somewhat expensive Oakley ‘Spectrol’ pot brackets.
The new issue 2 also corrected the small ault in PCB legending which showed Q2 the wrong
way around. It also incorporated two ‘PAN’ pads to allow or easier wiring to the sockets.
The LFO and LFO-NC outputs which had to share a pad on the old issue board now have
their own bu ered and isolated output signals. Any loading on the LFO output would not now
a ect the depth o modulation to the Equinoxe phaser.
The LED driver was made more complex. The issue 1 design simply relied on a resistor to
control the current through the LED. When the LFO output was very low the LED would
blank out completely. The issue 2 design controlled the LED through a constant current
source. There ore, although the LED will still vary in intensity and colour with the triangle
wave orm output, it never actually goes out. This gives a more use ul and pleasant display.
With issue 3, released in 2006, the circuit board was now ully RoHS compliant and was made
using a lead ree process. The OTA devices were now two LM13700 instead o our CA3080.
The CA3080 was made obsolete by Intersil, ormally Harris and RCA, and in any case was not
available in an RoHS orm. Even with this pro ound change in devices there are no discernible
di erences in sound between the issue 2 and issue 3 designs o the Equinoxe.
Also included with issue 3 PCBs was the ability to make the LFO output inverted or non
inverted. However, this was done by itting certain components and there ore had to be done
at the construction stage. The TUNE trimmer was given a bigger usable range and was made
easier to set.
Issue 4 boards were released in 2009. These were identical to issue 3 but or the addition o
Synthesizers.com power headers.
In late 2009 it was decided to move over to another type o pot. Vishay had pushed the prices
o their old Spectrol range up to such a degree it was not economic to continue to use them.
The BI 260P pot was a use ul alternative but stocks were hard to ind and the log taper pots
had a poor per ormance. Issue 5 boards use the Alpha 16mm pots, which are good quality
clones o the standard ALPS 16mm pot.
Issue 5 also incorporates a jumper to select between LFO modes and eatures a six way header
or expansion to the Deep Equinoxe daughter board.
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Calibration
There is only one trimmer to set up and it's pretty easy to do. Set the ' requency' and 'emphasis'
pots to their maximum value and the 'mod depth' and 'LFO rate' to the minimum values. Now
turn the trimmer to its ully clockwise position. Power the unit up and input a sawtooth
wave orm into the input. Any requency will do, but a low to medium note is best. Listen to
the output through your normal listening set up.
Now slowly turn the trimmer in anti-clockwise direction. The moment the sound alters in
texture stop turning. You may have to go back a little bit and do it again until you get it right.
It’ll probably end up being somewhere around its hal way point. What you are doing is setting
the top requency o the FREQUENCY pot. It's not terribly important that you set this
accurately, so don’t worry about it i you don’t get it absolutely right.
Final Comments
I hope you enjoy using the Oakley Equinoxe phaser module.
I you have any problems with the module, an excellent source o support is the Oakley Sound
Forum at Mu wiggler.com. Paul Darlow and I are on this group, as well as many other users
and builders o Oakley modules.
I you have a comment about this user manual, or have a ound a mistake in it, then please do
let me know.
Last but not least, can I say a big thank you to all o you who helped and inspired me. Thanks
especially to all those nice people on the Synth-diy, Oakley-Synths and Analogue Heaven
mailing lists and those at Mu wiggler.com.
Tony Allgood at Oakley Sound
Cumbria, UK
© December 2010
No part o this document may be copied by whatever means without my permission.
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