Intellijel Quad VCA

COMPLIANCE

FCC Compliance: This device complies with Part 15 of the FCC Rules. Operation is subject to the following two conditions: (1) this device may not cause harmful interference, and (2) this device must accept any interference received, including interference that may cause undesired operation. Changes or modifications not expressly approved by Intellijel Designs, Inc. could void the user's authority to operate the equipment. Any digital equipment has been tested and found to comply with the limits for a Class A digital device, pursuant to part 15 of the FCC Rules. These limits are designed to provide reasonable protection against harmful interference when the equipment is operated in a commercial environment. This equipment generates, uses, and can radiate radio frequency energy and, if not installed and used in accordance with the instruction manual, may cause harmful interference to radio communications.

CE Compliance: This device meets the requirements of the following standards and directives:

• EMC: 2014/30/EU
• EN55032:2015 ; EN55103-2:2009 (EN55024) ; EN61000-3-2 ; EN61000-3-3
• Low Voltage: 2014/35/EU
• EN 60065:2002+A1:2006+A11:2008+A2:2010+A12:2011
• RoHS2: 2011/65/EU
• WEEE: 2012/19/EU

INSTALLATION

Intellijel Eurorack modules are designed to be used with a Eurorack-compatible case and power supply. Intellijel recommends using Intellijel cases and power supplies.

Before installing a new module:

• Ensure your power supply has a free power header and sufficient available capacity. Sum the +12V, -12V, and +5V current draw for all modules, including the new one, and compare these sums to your case's power supply specifications. Only proceed if none of the values exceed the specifications. Otherwise, remove modules to free up capacity or upgrade your power supply.
• Ensure your case has enough free space (hp) to fit the new module. To prevent screws or debris from falling into the case and shorting electrical contacts, do not leave gaps between adjacent modules and cover all unused areas with blank panels. Avoid open frames or enclosures that expose the backside of any module or the power distribution board.

A tool like ModularGrid can assist in planning. Failure to adequately power modules may result in damage. If unsure, contact Intellijel before proceeding.

Installing Your Module

When installing or removing a module, always turn off the power to the case and disconnect the power cable to prevent injury or equipment damage.

Ensure the 10-pin connector on the power cable is connected correctly to the module. The red stripe on the cable must align with the -12V pins on the module's power connector. These pins are indicated with "-12V", a white stripe, or the words "red stripe". Most modules come with the cable pre-connected, but it is good practice to double-check.

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 aligns with the -12V pins on the bus board. On Intellijel power supplies, these pins are labeled "-12V" and have a thick white stripe. For other manufacturers' power supplies, consult their documentation.

Before reconnecting power: Double-check that the ribbon cable is fully seated on both ends and that all pins are correctly aligned. Misaligned or reversed cables can damage modules, power supplies, or other equipment.

After confirming connections, reconnect the power cable and turn on the modular system. Check that all modules have powered on and are functioning correctly. If any anomalies occur, turn off the system immediately and re-check cabling.

OVERVIEW

The Intellijel Quad VCA is a versatile four-channel variable response VCA. It features cascaded CV inputs and cascaded mix outputs, enabling various configurations. A boost switch provides additional amplification for low-level signals or subtle overdrive for audio. The Quad VCA is useful in any patch, offering more than just four independent VCAs.

Features

• Manual LEVEL control: Convenient for use as a mixer or for biasing when CV modulating with a bipolar LFO.
• Dedicated CV attenuators: Feature dual-color LEDs for monitoring bipolar CV signals (green for positive, red for negative).
• Response control: Continuously adjustable from linear to exponential per VCA.
• Cascaded CV: Each CV input is normalled to the adjacent one for cascaded control.
• Cascaded Mix Outputs: Each output is normalled to the mix input of the adjacent one. This allows adjacent sets to be used as submixes, or the fourth output can serve as a master mix output when other outputs are unpatched.
• BOOST switch: Increases the output level by approximately +6dB (double).

FRONT PANEL

Controls

• [1] CV Attenuator: Controls the amount of CV modulation sent to a channel's level. If a channel's CV input is unpatched, this knob brings up the CV signal from the preceding channel.
• [2] CV LED: A red/green LED for each channel indicating the post-attenuator level of the incoming CV signal.
• [3] Linear / Exponential Response: Adjusts the VCA's response to the LEVEL knob and CV input. Fully counterclockwise is exponential, fully clockwise is linear, with variable responses in between.
• [4] BOOST: When disabled (left position), the VCA's maximum linear gain is unity (1:1). When enabled (right position), the signal is boosted by approximately +6 dB (2:1).
• [5] LEVEL 1: Sets the base level (bias) for channel 1. A +5V CV input with the attenuator fully clockwise and response knob linear results in unity gain. The knob level is summed with the CV input.
• [6] LEVEL 2: Sets the base level for channel 2.
• [7] LEVEL 3: Sets the base level for channel 3.
• [8] LEVEL 4: Sets the base level for channel 4.

Inputs and Outputs

• [A] CV 1: CV input for channel 1 level control.
• [B] CV 2: CV input for channel 2 level control. If unpatched, takes CV from CV 1.
• [C] CV 3: CV input for channel 3 level control. If unpatched, takes CV from CV 2.
• [D] CV 4: CV input for channel 4 level control. If unpatched, takes CV from CV 3.
• [E] IN 1: Input for channel 1.
• [F] IN 2: Input for channel 2.
• [G] IN 3: Input for channel 3.
• [H] IN 4: Input for channel 4.
• [I] OUT 1: Signal output for channel 1. If unpatched, mixed into OUT 2.
• [J] OUT 2: Signal output for channel 2. If unpatched, mixed into OUT 3.
• [K] OUT 3: Signal output for channel 3. If unpatched, mixed into OUT 4.
• [L] OUT 4/MIX: Signal output for channel 4. If other OUT jacks are unpatched, this acts as a 4-channel mix output.

INSTRUCTIONS

4 Independent VCAs

To use the Quad VCA as four independent VCAs, ignore cascading CV and mixing functionality:

1. Connect the source signal to IN 1.
2. Connect OUT 1 to the destination input.
3. Connect a modulating signal (envelope, LFO, oscillator) to CV 1.
4. Turn LEVEL 1 fully counterclockwise to remove CV bias.
5. Adjust the CV input attenuator and Linear/Exponential Response control.

Repeat for channels 2, 3, and 4.

Level Bias

The LEVEL control can bias a channel's response, setting a "default" signal amount adjusted by external CV. This is useful for controlling modulation amounts.

Example: Controlling FM Amount

1. Connect the sine output of oscillator 1 (modulator) to IN 1 of the Quad VCA.
2. Connect OUT 1 to the FM input of oscillator 2 (carrier).
3. Use LEVEL 1 to set the FM amount (index).
4. Connect an envelope to CV 1 and adjust the attenuator to vary the FM index during playback.

Cascaded CV

The Quad VCA features cascading CV, allowing one CV input to control multiple channels. If a channel's CV input is unpatched, it responds to CV from the previous channel, subject to its own CV attenuation level.

1. Connect different oscillator outputs or sound sources to IN 1 and IN 2.
2. Connect a CV source (e.g., envelope) to CV 1.
3. Take output from OUT 2, or OUT 1 for parallel processing.
4. Use CV attenuators and response knobs to fine-tune CV response for each channel.

This can be extended to four channels.

Cascaded Mixing

The Quad VCA's outputs have a cascaded mixing feature, allowing it to function as a mixer:

1. Connect up to four sources to IN 1 through IN 4.
2. Take the output from the OUT 4/MIX jack.
3. LEVEL 1 through LEVEL 4 control the mix levels.
4. CV inputs (CV 1-4) can be left unpatched for manual mixing or used to automate mix levels on one or more channels.

Combinations

Combine the methods described above. For example, use cascaded mixing on channels 1-3 (outputting from OUT 3) and use channel 4 as an independent VCA. The module's versatility allows for creative combinations.