MYSTIC Circuits 3DVCA User manual

3DVCA Ofcial Manual
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3DVCA Ofcial Manual
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Contents
3DVCA 5
INSTALLATION 6
QUICK REFERENCE 8
FUNCTIONAL OVERVIEW 10
3 DIMENSIONS OF CONTROL 11
COMPASS DISPLAY 12
SCALING CURVES 13
INPUTS & OUTPUTS 14
NORMALIZATION ROUTING 15
SUMMING 16
PATCHING EXAMPLES WITH 3DVCA 17
MONO PATCHING WITH 3DVCA 18
STEREO PATCHING WITH 3DVCA 22
QUAD PATCHING WITH 3DVCA 26
CONTROL VOLTAGE PATCHING WITH 3DVCA 29

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www.mysticcircuits.com
Flexibility is what makes modular synthesis so special. Every input
and output is a portal to new ways of making music. Each module that
you add to your case expands the possible signal routings of the other
modules in your case exponentially. 3DVCA is designed to automate
these routings and give you a exible tool to send or mix signals across
your case. Designed to be a highly customisable connection matrix,
3DVCA packs a boat load of utility into a small 6HP package. Four
VCAs share the three macro controls: X, Y, and Z. As a group, they
shape incoming or outgoing signals and emulate the coordinates of a
point in 3 dimensional space. They allow the VCAs to work together in
mono, stereo, or quad conguration and accomplish a variety of
mixing, crossfading, or panning functions. For easy integration with
multiple 3DVCAs or other mixer modules, each VCA output has a
dedicated sum input. This allows an entire mix to be automatically
passed along to the next mixer in the chain. Each module is built with
high quality components, Sound Semiconductor VCAs, and rail-to-rail
OPA family op amps. On top of that, each VCA is fully DC coupled to
work predictably with any type of signal you throw at it. Exponentially
expand the routing potential of your modular system with the Mystic
Circuits 3DVCA.
3DVCA Ofcial Manual
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3DVCA Ofcial Manual
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INSTALLATION
Follow the installation instructions carefully to avoid module or rack damage.
1. Ensure the power connection is off before installing the device.
2. Identify 6HP of free rack space in which to install the module.
3. Connect the 10 pin connector from the IDC ribbon power cable to the header on the
rear side of the module by aligning correctly with the red stripe on the ribbon conductor
nearest to the -12V pin indicator on the header.
4. Insert the cable through the rack and connect the 16 pin side of the IDC ribbon cable to
the rack power supply header. Ensure that the pins are aligned correctly with the red
stripe on the ribbon conductor nearest to the -12V pin on the header.
5. Position the module into the dedicated rack position.
6. Attach the 2 x M3 screws by screwing into the 2 locator holes and the rack mount
taking care to not over tighten the screws.
7. Turn on the power to the rack.
8. The module will start up and be ready to use.
Ensure the following conditions are correct for trouble free installation.
• Rack power supply can accommodate all of the installed modules total current ratings.
3DVCA power requirements are +12V 45mA, -12V 45mA, +5V Not Used.
• 3DVCA is 30mm deep.
• Module power cable orientation is correct at both the rack and module side. Use the
IDC ribbon cable supplied with the module.
• Ensure the rack earth / grounding is correct.
• Take care to avoid patch cables falling into the rack or touching module PCB’s

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Power cable should only be connected
by 3DVCA with the red stripe aligned to
the red tag -12V on the power supply.
Connect power to the IDC Connector
Eurorack Installation.
-12V -12V
Power
Power
Back
3DVCA

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QUICK REFERENCE

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Y Control. Fades Upper & Lower VCA Pairs On / Off. Crossfade in stereo congs.
Z Control. Turns all active 4 VCA’s On - Slider Up or Off - Slider Down.
Z CV Input. External control voltage modulation input.
X Control. Fades Left & Right VCA Pairs On / Off. Pan in stereo congurations.
X CV Input. External control voltage modulation input.
Compass. LED visualisation of the 4 VCA Channels.
NW Sum Input. Allows an input to be summed to the North West output
NE Sum Input. Allows an input to be summed to the North East output
Y CV Input. External control voltage modulation input.
SW Input. South West positioned input, normalised to South East Input.
SE Input. South East positioned VCA input.
NW Output. North West positioned output normalised to South West output.
NE Output. North East positioned output normalised to South East output.
SW Output. South West positioned output normalised to North East output.
SE Output. South East positioned VCA output.
The VCA Input / Outputs can be used in Mono, Stereo or Quad congurations. Arrows on
the panel indicate the normalization structure. Normalization is only performed when a
destination jack socket is unplugged.
NW Input. North West positioned input, normalised to North East & South West.
SE Sum Input. Allows an input to be summed to the South East output
SW Sum Input. Allows an input to be summed to the South West output
NE Input. North East positioned VCA input.
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3DVCA Ofcial Manual
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FUNCTIONAL OVERVIEW
Basics of a VCA.
A VCA (Voltage Controlled Amplier) is a device that takes a voltage signal at the input
and adjusts the output level of that signal according to the level of a control voltage. This
function can be thought of as a voltage controlled attenuator. VCAs have the ability to
switch a signal on or off completely when controlled with a gate or gradually fade the
amplitude of that signal with a gradually changing control voltage. The most common use
of a VCA is to use an envelope to control the volume of an audio source in order to turn a
constant tone into more musical notes. In general, VCAs have a myriad of uses ranging
from adjusting the amount of modulation going to different control voltage inputs, changing
the volume of different notes in a sequence to allow accents or ghost notes, muting
voltage connections between different modules under voltage control, and so many other
functions. VCAs are probably the most important module in your system aside from audio
and CV signal generators.
Mystic Circuits 3DVCA - Quad Vector VCA.
Mystic Circuits 3DVCA is a quad VCA in a small 6HP form factor that can operate in mono,
stereo or quad congurations. Unlike a traditional quad VCA which allows independent
control over each VCA, 3DVCA uses 3 dimensional macro parameters to control all 4 VCA
channels together as a group. The X function gradually attenuates the Left / Right pairs of
VCA channels, the Y Function attenuates the Upper / Lower pairs of VCA channels and
the Z function controls the level of all active VCAs determined by the module's X and Y
settings.
The four VCA inputs and outputs are congured in a four quadrant conguration similar to
a geographic compass. As such, the 3DVCA LED display is called the ‘Compass’ and
visually represents the activity of all four VCAs. Similarly, the VCA inputs and outputs are
referred to as their corresponding North, East, South, and West positions. This will be
described in greater detail later in the manual.
Audio Input Modulation Input
Envelope CV
VCA
Audio output
Example: Generic VCA Principles