Intellijel Quadra User manual

Quadra & Expander Manual
Quadra & Expander
Quad Function / Envelope Generator
Manual Revision: 2018.08.22

Quadra & Expander Manual
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
Page 1

Quadra & Expander Manual
Overview
The Intellijel Quadra and Expander modules comprise four parallel function generators (more
commonly referred to as “Envelope Generators,”) plus numerous CV controls. The Quadra
function generator has three modes, AD (Attack, Decay), ASR (Attack, Sustain, Release) and
Cycle (a perpetually repeating AD envelope, which acts like a unipolar LFO). Each function can
be configured to have a linear or exponential curve, and each features a wide time-base control
from 0.5ms to over 30 seconds. The Expander enhances Quadra’s core functionality by allowing
attenuated voltage control over Attack and Decay for each function generator; plus a
Quadrature mode and an analog OR mixer for each function generator pair.
This manual discusses 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.
 
Page 2

Quadra & Expander Manual
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.
 
Page 3

Quadra & Expander Manual
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.
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.
Page 4

Quadra & Expander Manual
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.
Page 5

Quadra & Expander Manual
Quadra Front Panel
Controls
1. ATTACK - This knob (x4)
controls 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 - This knob (x4)
controls the fall-to-zero time. In
ASR mode this will act as the
release time. In Cycle mode the
total time of ATTACK plus
DECAY sets the frequency of
the LFO.
3. Exponential/Linear Switch -
This switch (x4) changes the
attack and decay curves.
Depending on what you are
patching the Quadra into, this
setting may need to be
changed. For example if you
patch into an exponential VCA
you’ll probably use linear mode.
The fastest envelope times are
achieved when in linear mode.
4. Mode Switch - This switch (x4)
sets each function generator to
one of three modes: AD, ASR or
Cycle mode. AD is an envelope
that ignores the incoming gate
time and is simply triggered.
Page 6

Quadra & Expander Manual
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 acts like a unipolar LFO.
5. LED - The brighter this LED (x4), the higher the function generator’s amplitude.
Inputs and Outputs
A. TRIG Inputs - Patch a trigger or gate signal here to launch the function generator. There
are four TRIG inputs — one for each of the four function generators.
B. ENV Outputs – The function generator is output here as a unipolar 0-8v control signal.
There are four ENV outputs — one for each of the four function generators.
Page 7

Quadra & Expander Manual
Expander Front Panel
Controls
1. 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.
2. Decay CV Input Attenuator -
Controls the range of CV
modulation applied to the
function’s decay phase.
3. End of Cycle LED - Indicates the
completion of an envelope’s
decay phase, corresponding with
a gate signal sent out of the EOC
output.
4. 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.
5. Quad 3+4 Mode Switch -
Engages Quadrature Mode for
3+4. When on, function 3’s end of
attack will trigger function
generator 4.
Page 8

Quadra & Expander Manual
6. ENV 2 Or Amount Attenuator - Sets the level of ENV 2 into OR 1+2.
7. ENV 3 Or Amount Attenuator - Sets the level of ENV3 into OR 3+4.
8. OR 1+2 LED - Shows the state of the function generator amplitude for OR 1+2.
9. OR 3+4 LED - Shows the state of the function generator amplitude for OR 3+4.
Inputs and Outputs
A. EOC – Outputs a high gate signal when the function generator has completed its Decay
phase. The associated yellow LED [3] indicates when the respective function generator
has reached the end of its cycle.
B. Attack CV Input - Allows an input signal to modulate attack time. This input is normalled
to Decay CV Input [C], allowing both to be controlled together or separately via CV.
C. Decay CV Input - Allows an input signal to modulate decay time.
D. 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. See ADSR Envelope Generation Using the OR
Outs and Quadrature Mode more information.
E. 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.
 
Page 9

Quadra & Expander Manual
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. Or 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.
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
Page 10

Quadra & Expander Manual
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 by
the examples in the left
column of this illustration.
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 (as
shown by the examples in
the right column of this
illustration). This is best used
with linear VCAs. The results
in this mode tend to have a more plucked character.
Page 11

Quadra & Expander Manual
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.
Page 12

Quadra & Expander Manual
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.
Page 13

Quadra & Expander Manual
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.
Page 14

Quadra & Expander Manual
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.
Page 15

Quadra & Expander Manual
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 Morgasmatron 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.
Page 16

Quadra & Expander Manual
Technical Specifications
Width
6 hp
Maximum Depth
44 mm
Current Draw
52 mA @ +12V
5 mA @ -12V
Page 17