Oakley VCO 1U User manual

Oakley Sound Systems
5U Oakley Modular Series
VCO Controller
1U wide oscillator master module
User Manual
V1.0.0
Tony Allgood B.Eng
Oakley Sound Systems
CARLISLE
United Kingdom

The suggested panel for fitting to an Oakley modular system with the Oakley CV/gate buss. The twin
keyboard control voltage (KCV signals that this module generates are connected to the VCOs behind the
front panel. If you do not have the facility for this you can make two of the front panel sockets carry the
two KCV signals instead.
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Introduction
T is is t e User Manual for t e issue 1 VCO Controller 5U module from Oakley Sound.
T is document contains a basic summary of its operation, ow our Oakley Buss works, a
guide to t e front panel controls, ow to connect it to your modules and finally calibration
procedures.
For t e Builder's Guide w ic contains information on ow to construct t e module from our
PCB and parts kits please visit t e main project webpage at:
ttp://www.oakleysound/cv-cont. tm
For general information regarding w ere to get parts and suggested part numbers please see
our useful Parts Guide at t e project webpage or ttp://www.oakleysound.com/parts.pdf.
For general information on ow to build our modules, including circuit board population,
mounting front panel components and making up board interconnects please see our
Construction Guide at t e project webpage or ttp://www.oakleysound.com/construct.pdf.
T e 5U VCO Controller Module
T e Oakley VCO Controller is a 1U wide module designed to function as a master controller
for two or more VCOs.
T e basic premise of t is module is to make it easy to control multiple oscillators. Quite often
you will require simple vibrato of two or more VCOs. Normally t is is done by patc ing one
LFO (low frequency oscillator) to your VCOs via a multiple. T is uses up a minimum of t ree
patc leads for two VCOs and t e vibrato dept needs to be set individually on eac VCO.
Wit t is module t e internal sine wave LFO is added directly to t e VCO's control buss, or
by using two of t e output sockets. One pot controls t e dept of t e LFO for bot or more
VCOs. T e LFO may be overridden by inserting a jack into t e CV IN socket on t e module
t us allowing ot er CVs to control multiple VCOs simply.
T e VCO Controller also features an inbuilt VCA (voltage controlled amplifier) module. T is
allows t e internal LFO, or any external CV, to be controlled by anot er CV. T is CV may be
aftertouc or modulation w eel outputs from your midi-CV interface. T us, vibrato dept can
be controlled wit your keyboard or keyboard's w eel or lever. Only one patc lead is required
to add touc sensitive or w eel controlled vibrato to your patc es – normally t is would
require a minimum of 2U of rack space, a multiple, and a w ole bunc of patc leads.
T e VCA wit in t is module can also be used separately as a ordinary VCA s ould you not
wis to use t e ot er features in t e module at any time.
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Also available are two octave switc es. T ese affect t e two keyboard control voltage (KCV)
outputs of t e module individually. T is eac VCO, or VCO bank, can be raised or lowered by
one octave at a flick of a switc . Eac KCV output uses a low impedance cable driver to
ensure no droops wit long signal runs and multiple loading.
Alt oug t is module was designed to work wit t e Oakley buss, w ic pipes around KCV
and gate signals around your modular, t e input and output sockets on t is module can be
assigned different purposes so as to suit individual requirements.
VCA control input is optionally low pass filtered so as to reduce stepping artefacts from midi
generated CVs. T is low pass filtered output is available via t e VCA CV OUT socket so you
can use it to control ot er modules.
T e internal LFO outputs are available individually from t e front panel as bot sine wave (+/-
5V) and square wave (+5V, 0V).
More about t e Oakley Buss and Module Normalisation
T e Oakley buss is a t ree way connector found on various modules. Pin 1 carries t e
keyboard CV (note control) and pin 3 carries gate (note on or off). T e VCO Controller
module taps into t e Oakley buss and creates two new busses for eac VCO bank. It also as
a buss t roug feature for easy wiring
T e word buss is per aps a little grand for somet ing t at as just two control lines and a
single ground. However, it still ad eres to t e principle of a common set of conductors t at is
available to all modules.
Normalising is t e process by w ic some signal pat s are already made for you. In ot er
words no patc leads are needed to make t ose connections; t ey are connected internally
eit er wit in t e module or between different modules but be ind t e faceplates. However,
normalising can always be overridden by t e user. T e name itself comes from t e use of
normalised connections on sockets. W en a socket does not ave a jack inserted it is in its
normal position. T ere is often a connection between t e signal lug of t e socket and an extra
contact called t e NC (normally closed) lug. It is t is t ird lug on t e socket t at is used for
t e normalisation. Inserting a jack plug will break t e connection between t e NC and t e
signal lug.
To elp us understand w ere normalisation is useful consider a VCO wit a 1V/octave socket
on its front panel. It is most likely to be used to for a keyboard control voltage (KCV). To
connect KCV to t is socket one would ordinarily need a patc lead. But imagine a system
w ere you ave four VCOs and two VCFs t at all need t e same KCV signal. It can take
many patc leads to do t is; seven if you ave a large multiple panel. Now suppose t at t e
NC lug of every 1V/octave socket is connected to a common KCV bus. All six modules can
now be driven wit out t e need for t ose seven patc leads. T is saves you leads, time, and
also gives you a better working environment because you don’t ave to fig t your way
t roug a tangle of leads to get to t e module’s knobs. Inserting a jack into one of t ose
sockets would disconnect it from t e KCV bus, so you still ave complete modularity.
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T e Oakley VCO as a Oakley Buss input eader on its socket board. Pin 1 of t is eader is
connected to t e NC lug of t e 1V/octave input socket. So any voltage on pin 1 of t is eader
is automatically connected to t e module's 1V/octave input unless as jack is inserted into t at
socket.
Normalising is frowned upon by some people, and loved by ot ers. Most modulars do ave
some form of normalising. T e Roland System 100 probably as t e ig est degree of
normalising. You don’t even need a patc lead to get t at one to sing. T e MOTM as no
form of external normalising, alt oug t ere are normalising routes wit in eac module.
W en I first started building my own modular system, I t oug t t at normalisation was a bad
t ing. Like preset memory patc es I t oug t it would stifle creativity by making t ings a little
too easy. However, in practice I noticed t at I was routing CV and gate to t e same locations
in my modular for almost all my patc es. So I decided to provide some form of limited
normalising. I c ose to normalise just KCV and gate. No audio normalisation was allowed. It
was easy to do, and proved very effective.
T e issue 2 Dizzy PCB, our main form distributing power around our larger modular systems,
includes a t ree way normalising buss w ic we call t e Oakley Buss. T is Oakley standard,
originally created wit t e Dizzy issue 1 PCB, gave us just two lines; t e KCV and Gate
busses. T ese are accessed by t e t ree way 0.1” eaders. Pin 1 of eac eader is KCV and
pin 3 is Gate. Pin 2 was connected to ground on t e first board, but some customers modified
t e board to give a t ird CV bus. T e current issue of t e Dizzy board leaves it floating so you
can now use it to normalise a t ird CV line if you wis . T ere are more details about t is in
t e Dizzy User Manual and Builder's Guide.
Eac module t at you wis to connect to t e normalisation buss needs to ave a suitable
lengt of wire terminating in a 3-way 0.1” eader. You’ll probably only need to use one pin
for eac module, since very few synt esiser modules actually use KCV and gate toget er. T e
wire end of t e interconnect needs to be connected to t e NC lug on t e relevant socket, ie.
1V/octave or gate. Be sure t at you remove any existing normalising on t e socket t at you
want to use. Note t at some MOTM and Oakley modules ave t e NC lug connected to
ground.
T e Oakley VCO, midiDAC and ot er modules already ave t e t ree pin eaders on t e main
or socket boards ready for easy direct connection to t e Dizzy or VCO Controller module.
You may feel t at adding little single, or double, wire tails to your MOTM modules is not a
good idea. It is a per aps little untidy. But I certainly would recommend to try it out if you use
your modular for straig tforward musical applications.
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Calibration
T e unit as seven trimmers and t us may seem a little daunting to trim correctly. However,
t e unit as been designed so t at it is easy to set up and no special equipment is required
ot er t an a guitar tuner or a decent set of ears.
Once t e unit as warmed up nicely I recommend setting up t e unit in t e order t at t ese are
presented ere. I will assume t at your VCOs are already in tune. If not do not attempt to trim
t e VCO Controller first since it requires t e VCOs to be perfectly in tune.
Turn t e lower two pots to t eir minimum value. Ensure t at t e two switc es are in t eir
middle positions.
SCL1 – T is trimmer sets t e scale of t e KCV1 output.
If you are using t e Oakley Buss your VCO will be already connected to t e VCO Controller
module via t e KCV1 eader, and t e VCO Controller will be connected to t e system's
Oakley Buss or direct from t e midi-DAC. You need to do t e following:
Connect up your VCO so you can ear t e output. Set it up so you can measure t e frequency
of t e VCO wit a guitar tuner or suitable VST plug-in in your DAW. Now connect your
VCO's 1V/octave input to t e output of your midi-CV convertor or analogue keyboard. Play a
note somew ere near t e top of t e keyboard. Tune in t e VCO to t at note as accurately as
you can wit t e coarse and fine controls on your VCO.
Now remove t e patc lead from t e VCO's 1V/octave input and your VCO will now be
receiving t e KCV1 signal from t e VCO Controller module. Play t e same note again on t e
keyboard and adjust SCL1 until it gives you exactly t e same note as you eard before. Try to
be as accurate as you can.
Now play a few notes and ensure t at t e VCO is tracking nicely.
If you do not ave t e Oakley Buss t en you will ave to make your connections wit patc
leads.
Connect up your VCO so you can ear t e output. Set it up so you can measure t e frequency
of t e VCO wit a guitar tuner or suitable VST plug-in in your DAW. Now connect your
VCO's 1V/octave input to t e output of your midi-CV convertor or analogue keyboard. Play a
note somew ere near t e top of t e keyboard. Tune in t e VCO to t at note as accurately as
you can wit t e coarse and fine controls on your VCO.
Now connect t e 1V/octave input lead to t e Key-CV1 output of t e VCO Controller. Unlike
t ose wit t e internal Oakley Buss you will ave made t is output available at t e front panel
of t e VCO Controller module. Connect also t e Key-CV IN socket to t e output of your
midi-CV convertor. T e VCO Controller is now controlling t e VCO's pitc . Play t e same
note again on t e keyboard and adjust SCL1 until it gives you exactly t e same note as you
eard before. Try to be as accurate as you can.
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SCL2 – T is trimmer sets t e scale of t e KCV2 output
Repeat t e above but wit your second VCO and use t e Key-CV2 output.
T e purpose of bot SCL trimmers is to ensure t at t e VCO Controller adds not ing to t e
CV signal w en t e two dept pots are at t eir minimum settings and t e switc es are in t eir
middle positions.
+OC – T is trimmer determines t e note played w en any octave switc is set to +1.
Play a note somew ere in t e middle of t e keyboard, say a low A at 440Hz. It s ould be in
tune. Now flick t e top switc to +1 and t e VCO t at is connected to KCV1 s ould go up in
pitc . Adjust +OCT so t at t e pitc is exactly one octave ig er t an it was w en t e switc
was in its middle position. Flick it back and fort a few times to make sure t e interval is
exactly an octave.
-OC – T is trimmer determines t e note played w en any octave switc is set to -1.
Play t e same note on t e keyboard. Now flick t e top switc to -1 and t e VCO t at is
connected to KCV1 s ould go down in pitc by about an octave. Adjust -OCT so t at it is
exactly an octave lower.
Ensure t at t e KCV2 output is similarly affected. T ere s ould be no appreciable difference
in octave intervals between KCV1 and KCV2.
Note t at tweaking +OCT will affect t e -1 octave setting as well as t e +1. If you tweak t e
+OCT trimmer for some reason, you will ave to re-tweak t e -OCT one as well.
OFFSE – T is trimmer adjusts t e control breakt roug of t e internal VCA.
Plug an unconnected patc lead into VCA IN and let t e ot er end ang so t at it doesn't
touc anyt ing. Now connect your amp or mixer to t e VCA OUT socket (not t e VCA CV
OUT) so you will be able to ear w at is t e VCA is doing. Keep t e volume down low for
t e moment. Connect t e SQR OUT of t e module into t e VCA CV IN. And turn up t e
volume slowly. You s ould be able to ear a t umping in time wit t e modules LFO. Turn
t e rate up a bit if its going too slow.
Now adjust t e OFFSET trimmer until t e t umping is minimised. You may ave to turn your
amp up a bit to make sure t e last remnants are reduced to t eir lowest settings.
Now unplug everyt ing. It's time to create t e a nice sine wave. If you ave a oscilloscope
t en t is will be easier but if not do not fret.
Using t e 'scope adjust t e two trimmers, SHAPE and SYM, until you get t e best s ape sine
wave from t e SINE OUT socket.
If you aven't got a 'scope, you can use your ears. Turn t e LFO RATE pot all t e way up.
Listen to t e sine wave output. You will ear a deep bass tone. Adjust t e SHAPE and SYM
pots until you get t e dullest sound wit minimal overtones.
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Final Comments
I ope you enjoy using t e Oakley VCO Controller.
If you ave any problems wit t e module, an excellent source of support is t e Oakley Sound
Forum at Muffwiggler.com. Paul Darlow and I are on t is group, as well as many ot er users
and builders of Oakley modules.
If you ave a comment about t is user guide, or ave a found a mistake in it, t en please do let
me know.
Last but not least, can I say a big t ank you to all of you w o elped and inspired me. T anks
especially to all t ose nice people on t e Synt -diy and Analogue Heaven mailing lists.
Tony Allgood at Oakley Sound
Cumbria, UK
© February 2010 – updated December 2011
No part of t is document may be copied by w atever means wit out my permission.
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