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LRR Eurorack Modules

JVCA Eurorack Module

This Eurorack module contains 2 JFET based voltage-controlled amplifiers (VCA). VCA’s are a core component in synths. They’re commonly used in conjunction with an envelope generator for shaping
sounds, or with two oscillators for tone synthesis. The inputs and outputs are buffered using fast professional audio grade op-amps to maintain signal integrity and performance.

Specs

SizeWidth: 4 HP
Depth: 42 mm
Power360 mW
12 V15 mA
-12 V15 mA
Channel
Definitions
1 (knob)User control knob/
CV DC offset
2 (CV)Control Voltage
0 to 5 V range
3 (SIG:IN)Input Signal
-5 to +5 V range
4 (SIG:OUT)Output Signal

Power

The module uses a standard 10 pin Eurorack connector with polarity marked

Inputs and Outputs

1. Knob

Adds a DC offset from 0 to 5 volts to the control voltage.

2. CV

This is the control voltage gain input, and it is normalized to 0 V. The recommended input range is 0 to 5 V. Voltages less than 0 will have the same gain as 0 V, and Voltages greater than 5 V will have the same gain as 5 volts.

3. Sig:In

The signal input is DC-coupled and will accept audio or CV signals. The recommended input range is -5 to +5 V. Voltages outside this range will cause increased distortion.

4. Sig:Out

Signal output

Inputs are tolerant to voltages from -12 V to + 12 V. Exceeding this range will damage the module.

Gain Response

The response of the VCA is exponential. A representative plot showing gain vs control voltage is shown in Figure 1.

Figure 1. Gain vs Control Voltage

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