Intellijel Quadra User manual

Quadra Manual v1.00
Quadra & Expander
Quad Function / Envelope Generator

Quadra Manual v1.00
Table of Contents
Table of Contents
Overview
Quadra Features
Additional Expander Features
Installation
Before Your Start
Installing Your Module
Quadra Front Panel
Controls
Inputs and Outputs
Expander Front Panel
Controls
Inputs and Outputs
Functions and Envelopes
Linear Versus Exponential Shapes
Quadrature Mode
ADSR Envelope Generation Using the OR Outs
Patch Examples
Technical Specifications
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Quadra Manual v1.00
Overview
The Intellijel Quadra and Expander modules comprise four parallel function generators (more
commonly referred to as  “Envelope Generators”. The Quadra function generators have three
modes, AD (Attack, Decay), ASR (Attack, Sustain, Release) and Cycle (perpetually repeating
AR envelope or unipolar LFO). Each function can be configured to have a linear or exponential
curve and they feature a wide time base control from 0.5ms to over 30 seconds. The Expander
enhances the core functionality by allowing attenuated voltage control over Attack and Decay
for each function generator, a Quadrature mode, and an analog OR mixer for each function
generator pair.
This manual will cover both the Quadra and its optional Expander module.
Quadra Features
●Four function generators with Attack and Decay times ranging from from 0.5 milliseconds
to over 30 seconds.
●Three modes: AD (attack, decay), ASR (attack, sustain, release), Cycle (AD envelope
loops)
●Exponential and Linear envelope curves
Additional Expander Features
● Four End of Cycle pulse outputs corresponding to the four function generators.
● Voltage control of attack and decay (with attenuators) of all four envelopes
● Two analog OR (Also known as Peak Circuit) logic outputs that are normalled to the two
pairs of envelopes with attenuators.
● Special Quadrature modes.
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Quadra Manual v1.00
Installation
Intellijel Eurorack modules are designed to be used with a Eurorack-compatible case and power
supply.
Before Your Start
Before installing a new module in your case you must ensure your case’s power supply has
sufficient available capacity to power the module:
● Sum up the specified +12V current draw for all modules, including the new one. Do the
same for the -12 V and +5V current draw. The current draw will be specified in the
manufacturer's technical specifications for each module.
● Compare each of the sums to specifications for your case’s power supply.
● Only proceed with installation if none of the values exceeds the power supply’s
specifications. Otherwise you must remove modules to free up capacity or upgrade your
power supply.
You will also need to ensure you have enough free space (hp)  as well as free power headers in
your case to fit the new module.
You can use a tool like ModularGrid to assist in your planning. Failure to adequately power your
modules may result in damage to your modules or power supply. If you are unsure, please
contact us before proceeding.
Installing Your Module
When installing or removing a module from your case always turn off the power to the case and
disconnect the power cable. Failure to do so may result in serious injury or equipment damage.
Ensure the 10-pin connector on the power cable is connected correctly to the module before
proceeding. The red stripe on the cable must line up with the -12V pins on the module’s power
connector. The pins are indicated with the label -12V, a white stripe next to the connector, the
words “red stripe”, or some combination of those indicators.
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Quadra Manual v1.00
Most modules will come with the cable already connected but it is good to double check the
orientation. Be aware that some modules may have headers that serve other purposes so
ensure the cable is connected to the right one.
The other end of the cable, with a 16-pin connector, connects to the power bus board of your
Eurorack case. Ensure the red stripe on the cable lines up with the -12V pins on the bus board.
On Intellijel power supplies the pins are labelled with the label “-12V” and a thick white stripe:
If you are using another manufacturer’s power supply, check their documentation for
instructions.
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Quadra Manual v1.00
Once connected, the cabling between the module and power supply should resemble the
picture below:
Before reconnecting power and turning on your modular system, double check that the ribbon
cable is fully seated on both ends and that all the pins are correctly aligned. If the pins are
misaligned in any direction or the ribbon is backwards you can cause damage to your module,
power supply, or other modules.
After you have confirmed all the connections, you can reconnect the power cable and turn on
your modular system. You should immediately check that all your modules have powered on
and are functioning correctly. If you notice any anomalies, turn your system off right away and
check your cabling again for mistakes.
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Quadra Manual v1.00
Quadra Front Panel
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Quadra Manual v1.00
Controls
1. ATTACK - These knobs control the time of the attack portion of the function (rising from
zero to the maximum level). Slower times will create a fade in effect while faster times
are used for snappy percussive sounds.
2. DECAY - These knobs control the fall to zero time. In ASR mode this will act as the
release time. In Cycle mode the total time of attack and decay set the frequency of the
LFO.
3. Exponential/Linear Switch - This will change the  shape of the attack and decay
sections. This setting will alter the time base of the function generator. Depending on
what you are patching the Quadra into, this setting may need to be changed. For
example if patching into an exponential VCA you should use linear mode. The fastest
envelope times are achieved when in linear mode.
4. Mode Switch - Selects AD, ASR or Cycle mode. AD is an envelope that ignores the
incoming gate time and is simply triggered. This is often used with sequencers. ASR is
similar to an ADSR in that it continues to sustain while the input gate is high. Cycle mode
is like an LFO.
5. LED -  Shows the state of the function generator amplitude.
Inputs and Outputs
6. TRIG Inputs - Patch trigger or gate signals here to launch the function generators.
7. ENV Outputs – The function generator is output here as a unipolar 0-8v control signal.
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Quadra Manual v1.00
Expander Front Panel
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Quadra Manual v1.00
Controls
A. End of Cycle LED - Indicates the completion of an envelope’s decay phase,
corresponding with a gate signal sent out of the EOC output.
B. Attack CV Input Attenuator - Controls the range of CV modulation applied to the
function’s attack phase. The range increases as the knob turns clockwise. Generally
best results are achieved by starting at zero and then increasing the amount until the
desired level of modulation is discovered.
C. Decay CV Input Attenuator - Controls the range of CV modulation applied to the
function’s decay phase.
D. Quad 1+2 Mode Switch - Engages Quadrature Mode for 1+2. When on (switched to the
right), function 1’s end of attack will trigger function generator 2.
E. Quad 3+4 Mode Switch - Engages Quadrature Mode for 3+4. When on, function 3’s
end of attack will trigger function generator 4.
F. OR 1+2 LED - Shows the state of the function generator amplitude for OR 1+2
G. ENV 2 Or Amount Attenuator - Sets the level of ENV 2 into OR 1+2.
H. ENV 3 Or Amount Attenuator - Sets the level of ENV3 into OR 3+4.
I. OR 3+4 LED - Shows the state of the function generator amplitude for OR 3+4
Inputs and Outputs
J. EOC – Outputs a high gate signal when the function generator has completed its Decay
phase. The above yellow LED (A) indicates when the respective function generator has
reached the end of its cycle.
K. Attack CV Input - Allows an input signal to modulate attack time. This input is normalled
to Decay CV Input (D), allowing both to be controlled together or separately via CV.
L. Decay CV Input - Allows an input signal to modulate decay time.
M. OR 1+2 Output - This is the mixed OR signal of 1+2. When using QUAD 1+2 mode use
this output for complex function shapes.
N. OR 3+4 Output - This is the OR mixed signal of 3+4. When using QUAD 3+4 mode use
this output for complex function shapes.
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Quadra Manual v1.00
Functions and Envelopes
While envelope generators may not seem as exciting as other modules like filters, oscillators,
and effects, they play a critical role in creating movement and life in a patch. If you come from a
more traditional synthesizer background, all this talk of function generators and Quadrature
mode may seem overwhelming. Perhaps you find it strange that we talk about the Quadra as an
envelope generator but then do not mention the most common envelope type, the ADSR. This
is because the design concept of the Quadra is inspired by what is commonly referred to as
“West Coast” synthesis concepts (a nod to Don Buchla, a pioneer in synth design from
California). You can think of each function generator in the Quadra as a simple envelope
generator. However, since the Quadra can also create very complex looping LFO shapes in
Quadrature mode, or create complex interacting combinations using the OR outputs, we use the
more traditional name of “Function Generator”.
You can use the Quadra on its own as four AD or ASR envelope generators. If you are not
using a traditional keyboard controller AD mode is preferred by many since it is independent of
the incoming gate times. Once the AD is triggered, it will move through its stages until
completion. This is ideal for sequencer or random based patches. You can use the Expander
CV inputs to control the decay time which is like controlling the gate time at the sequencer, but
has a different sound.
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Quadra Manual v1.00
Why would you use so many envelopes? If you consider the average synthesizer voice needs at
least two envelopes, one for final VCA, the other for filter cutoff, it is not hard to imagine in a
more complex voice how to use more. For example, another AD envelope could be used to
control the modulation index of a two VCO FM patch. You can use envelopes to control the
amount an LFO controls the filter via another VCA, or use a multed VCA in parallel with the final
VCA to act as an effect send. You can see how with a little imagination and a lot of VCAs you
will quickly run out of envelope generators, especially once you start designing percussive
sounds.
Linear Versus Exponential Shapes
Linear Mode (switch to the right) - The Quadra makes straight lines as shown below on the left.
This is best used with exponential VCAs. The fastest envelope times are achieved when in
linear mode.
Exponential Mode (switch to the left) - The Quadra creates a musical curved shape found on
many classic envelope generators. This is best used with linear VCAs. The results in this mode
tend to have a more plucked character.
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Quadra Manual v1.00
Quadrature Mode
Quadrature Mode links the function generators into two pairs of looping envelopes that have
interdependent timing. It vaguely resembles two waveforms that are phase shifted 90 degrees
relative to each other (hence the “quadrature” label). Each pair is independent and functions
identically, so we will concentrate on the function generator pair 1+2 for this section.
In this mode, 1 is triggered and retriggered by its own end of cycle. 1 will not enter its decay
phase until both 1 and 2 have completed their attack phase. 2 can either be triggered by the end
of attack of 1, or by a gate or pulse sent to the TRIG 2 input. 2 will not enter its decay phase
until it has completed its attack, and 1 completes its decay. This means that sometimes 2 will
retrigger before completing its decay phase because 1 may complete its attack first. If 2 is set to
cycle with short enough attack and decay values, it will cycle during 1’s attack.
It may take some trial and error to gain a full understanding of how this mode works, and how
best to take advantage of its behaviour. Quadrature mode is great for creating out of phase
modulation of two related parameters. For example, modulating the waveforms or pulse width of
two oscillators.
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Quadra Manual v1.00
ADSR Envelope Generation Using the OR Outs
By using the OR output of the Expander and triggering two paired function generators with the
same trigger or gate signal, an ADSR envelope can be achieved. For example, with 1 and 2
triggered together, if 1 is set to AD and 2 is set to ASR, the OR 1+2 output will send an ADSR
envelope. The Envelope 2 Amount Attenuator can be used to set the sustain level.
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Quadra Manual v1.00
Patch Examples
Patch 1: Basic Voice With ASR Envelopes
This is a simple patch that uses the Quadra as two ASR envelope generators for a basic
synthesizer voice. The reason ASR is chosen over AD in this example is because ASR will
sustain as long as the keyboard key is held down. This is because an ASR envelope has a
sustain section that stays high as long as the input gate is high. Once the keyboard key is
released and the input gate goes low, the envelope will move into its decay phase, which in
ASR mode is referred to as release. ASR stands for Attack, Sustain, Release.
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Quadra Manual v1.00
Patch 2: Basic West Coast Voice (Requires Expander)

This patch uses the Expander for its CV inputs as well as Quadrature mode.
A simple example of what is referred to as a “West Coast” voice. As with most west coast style
patching, a filter is not used for timbre control, instead linear frequency modulation (FM) is used
in a two-operator FM configuration. Quadra’s function 1 in AD mode controls the amount of
harmonics by controlling VCA 1’s level. Quadra’s function 2 also in AD, and VCA 2 are used for
the final output volume. Make sure you adjust the pitch of VCO 1 to alter the harmonics
produced by VCO 2.
Although a sequencer is used in this example, a keyboard could be used instead. Adding more
LFOs and sequencers to various timbre shaping parameters such as VCO 1 pitch and Quadra’s
attack and decay CV inputs is definitely worth trying.
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Quadra Manual v1.00
Patch 3: Kick Drum

This is a very simple patch that will produce a nice snappy kick drum depending on the VCO
used. A self oscillating VCF can also be used, for example the Intellijel Korgasmatron makes
excellent fat kicks with a bit of Q drive since it is not a true sine wave.
First take the sine wave output of your VCO and patch it into your VCA. Then patch the same
trigger from a sequencer or other source into Quadra’s TRIG 1 and TRIG 2 inputs. Patch ENV 1
into the pitch input on your VCO, using an attenuator if the oscillator does not have an
attenuator on the pitch or FM input. Without reducing the range of the AD signal, the kick will
sound more like a zap than a snap. ENV 2 connects to the CV input of your VCA to control the
amplitude of the sound. Both ADs should be set with a fast attack and a medium decay, with the
pitch decay shorter than the amplitude decay. To reduce clicks, slow down the attack of the AD
feeding the VCA. Try starting at 9 o’clock. Adjust the pitch of your VCO and the attenuator until
you get a nice boomy tone. Then adjust the Quadra’s AD times until you get the shape and
timbre of the kick that you desire.
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Quadra Manual v1.00
Technical Specifications
Width
6 hp
Maximum Depth
44 mm
Current Draw
52 mA @ +12V
5   mA @ -12V
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