ADDAC System ADDAC308 Light to CV ()
It doesn’t make sound—but it breathes light into your modular, turning flickers and shadows into living voltage.
Overview
The ADDAC308 Light to CV isn’t a voice, an oscillator, or an envelope—it’s a translator. It listens to light and speaks in control voltage, giving your modular synth a sixth sense. Part of ADDAC System’s 300-series Expressive Controls, this 4hp Eurorack module turns ambient shifts, hand shadows, or deliberate flashlight sweeps into dynamic CV signals that can modulate pitch, filter cutoff, panning, or anything else with a CV input. It’s not just a utility; it’s a performance interface disguised as a utility.
At its core is a light sensor connected via a standard 3.5mm jack, letting you place the sensor outside your rack—on a table, taped to a wall, or even mounted on a moving object. The sensor itself is enclosed in a jack socket, so it’s rugged and patch-cable-ready. Inside the module, an LED and LDR (light-dependent resistor) are housed in patch cable-compatible enclosures, making it easy to build custom light paths or feedback loops. You could, for example, patch the module’s output to a VCA controlling an external light source pointed back at the sensor—creating organic, self-modulating systems that breathe and pulse on their own.
Owners report using it in subtle, almost cinematic ways—nudging parameters just enough to feel alive, like a slow sunrise opening a filter over three minutes. Others go full theatrical, using hand motions to warp textures in real time, turning a modular setup into something closer to a light sculpture. One user described using it to “alter different aspects of Mutable Instruments Elements” in a nuanced, evolving patch, while another shared a video where the ADDAC308 controls both Elements and Rings, creating a shimmering, light-driven performance that feels more like conducting than knob-turning.
It’s not a module you rack up for stacking fat leads. It’s the one you reach for when you want your synth to feel less like a machine and more like an environment.
Specifications
| Manufacturer | ADDAC System |
| Width | 4hp |
| Depth | 4.5cm |
| Power consumption | ±50mA |
| Outputs | 2 Bipolar CV Streams (Output and Inverted Output) |
| Controls | Sensitivity, Response (3 fixed settings: medium/fast/slow), Gain, Offset, Inverted Offset |
| External sensor | enclosed in a jack socket |
| Features | The module includes an LED and LDR (light-dependent resistor) housed in patch cable compatible housings. |
Key Features
Light to Voltage Translation
The ADDAC308’s entire purpose is to convert incoming light into control voltage. More light hitting the sensor results in a higher CV output on the main output; the inverted output does the opposite—more light, lower voltage. This bipolar behavior gives you immediate polarity options without needing an inverter module. Whether you’re using it to open a filter with increasing brightness or drop a pitch as a shadow passes, the response is intuitive and immediate.
External Sensor with Flexible Placement
The light sensor connects via a standard 3.5mm mono cable, meaning it’s not confined to your rack. You can dangle it over your synth case, tape it to a lamp, or hide it under a translucent surface on your desk. This opens up performance possibilities—imagine placing your hand above the sensor to swell a drone, or using a rotating gobo to create rhythmic modulation. The sensor’s jack-socket housing makes it durable and easy to integrate into a permanent setup.
Dual Outputs with Independent Offset
You get two CV streams: one normal, one inverted. Each has its own offset control—Offset for the main output, Inverted Offset for the second. This means you can bias each output to sit in a specific voltage range, say 0–5V for a VCO pitch input or -2.5V to +2.5V for a wavetable position. The Gain knob sets the overall amplitude for both outputs, letting you scale the response to match your system’s expectations.
Response Switch for Slew Control
The Response control is a switch with three fixed settings: slow, medium, and fast. It applies slew to the raw light signal, smoothing out abrupt changes. Set to slow, it turns quick hand motions into gentle swells—perfect for ambient textures. Fast mode tracks rapid changes, useful for rhythmic or percussive modulation. It’s not a continuously variable slew, but the three-step design keeps the module simple and focused.
Sensitivity Adjustment for Low-Light Use
The Sensitivity knob adjusts how responsive the sensor is to light levels. Turn it up, and the module becomes reactive even in dim environments—ideal for studio use where you might not want to blast a spotlight on your rack. In bright conditions, you can dial it back to prevent clipping or overmodulation. It’s a small knob with a big impact on usability across different lighting scenarios.
LED and LDR in Patchable Housings
Beyond the external sensor, the module includes an internal LED and LDR, each housed in patch cable-compatible enclosures. This lets you create closed-loop systems—patch a CV source to the LED input, drive it with an LFO, and let it shine on the LDR, generating a secondary CV. Or use it to build opto-isolated feedback paths, where light, not electricity, carries the signal. It’s a nod to experimental, patch-centric users who like to blur the line between module and medium.
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