The Death By Audio PHOTO MODULATOR is a compact, light-sensitive controller for expression pedal-compatible effects. Instead of rocking a pedal, you shine a light, such as a strobe, flashlight, stage light or even a lava lamp, onto its sensor to sweep the effect one way, and cover it in shadow to sweep the other. Death By Audio describes it plainly: "It works just like an expression pedal: light = toe down, dark = heel down."1
It is a passive accessory, not an effect: there is no power, no battery and no controls, just a light sensor and a quarter-inch jack. It launched alongside the Crossover Fuzz, which it was designed to pair with, and Pedal of the Day described it in August 2025 as "a device that uses light to control your sound."2
Expression control by light
The Photo Modulator replaces the rocking motion of an expression pedal with light. Bright light on the sensor sweeps the connected effect one way, toward its toe-down setting; shadow sweeps it back toward heel down. Because the sensor responds to whatever light falls on it, the source can be anything from a flashlight held in the hand to a stage light or a slow-moving lava lamp, which turns the speed and rhythm of the light into a playing input of its own.1
Death By Audio's product page includes demo sound samples made with the Crossover Fuzz, Rooms, Evil Filter, Time Shadows II, Boss DD-8, Moog Moogerfooger, EarthQuaker Devices Rainbow Machine and Afterneath, and the Rainger FX Reverb-X, giving a sense of the range of effects it can drive.1
How the photoresistor circuit works
The circuit is deliberately simple. At its heart is a cadmium-sulfide photoresistor connected between the tip and ring of the quarter-inch jack. In bright light its resistance drops below 1k, and in shadow it rises, so the amount of light on the sensor sets the resistance the host pedal reads.1
A 47k resistor connects the ring to the sleeve, which Death By Audio says mimics the behavior of the potentiometer found in most passive expression pedals. From the host pedal's point of view, the Photo Modulator looks like a conventional expression pedal whose treadle position is set by light rather than by foot.1
"The PHOTO MODULATOR uses a passive photoresistor circuit to allow almost any expression pedal-compatible pedal to be manipulated by light."
Connections and compatible pedals
The unit is housed in a right-angle quarter-inch jack for an ultra-small footprint, which Death By Audio notes makes it easy to aim the sensor at your chosen light source. It plugs straight into a pedal's expression input.1
Death By Audio names these as compatible:
- Rooms
- Evil Filter
- Crossover Fuzz
- "many of your favorite expression pedal-compatible effects"1
Pedal of the Day, reviewing the Crossover Fuzz and Photo Modulator together, wrote that "the Photo Modulator just adds to the intrigue and special nature of this pedal."2
Because it contains a cadmium-sulfide photoresistor, the Photo Modulator is not compliant with EU Directive 2011/65/EU (RoHS), UK RoHS, China RoHS, K-RoHS in Korea or Taiwan RoHS. Death By Audio states it cannot be sold, shipped or distributed in the European Union, the United Kingdom, China, Korea or Taiwan.1
Price, warranty and availability
Death By Audio lists the Photo Modulator at $39.00 USD, and Guitar Pedal X reported the same $39 price and described it as available when it launched in August 2025.123
One warranty point matters before buying: Death By Audio states the Photo Modulator is not covered by its lifetime warranty, because it is not an effect pedal. It is eligible for the company's standard 30-day return policy.1
Questions
Does the Death By Audio Photo Modulator need a battery?
No. Death By Audio states that the Photo Modulator requires no batteries and no power supply at all. It is a passive device: a cadmium-sulfide photoresistor inside changes resistance with light, so there is nothing to power. That also means it adds nothing to the current draw of your pedalboard.
What does the Photo Modulator plug into?
It plugs into the expression pedal input of a compatible effect using a right-angle quarter-inch jack. Death By Audio names the Rooms, Evil Filter and Crossover Fuzz as compatible pedals, and says it works with many other expression-control pedals. A 47k resistor between ring and sleeve mimics the potentiometer in a passive expression pedal.
Why can't the Photo Modulator be sold in the European Union?
The cadmium-sulfide photoresistor at its heart contains cadmium, which puts the device outside the RoHS limits in several markets. Death By Audio says it cannot be sold, shipped or distributed in the European Union, the United Kingdom, China, Korea or Taiwan.
Does the Photo Modulator work with any expression input?
Death By Audio lists the Rooms, Evil Filter and Crossover Fuzz, and says it works with many expression pedal-compatible effects. Its 47k ring-to-sleeve resistor mimics a passive expression pedal's potentiometer, so it suits pedals expecting that arrangement, but the maker does not claim universal compatibility with every expression input.
Is the Photo Modulator covered by the lifetime warranty?
No. Death By Audio states the Photo Modulator is not covered by its lifetime warranty because it is not an effect pedal. It is eligible for the company's standard 30-day return policy.
How much does the Photo Modulator cost?
Death By Audio lists it at $39.00 USD on its product page as of October 2026. Guitar Pedal X also reported the $39 price when the unit launched in August 2025, and described it as available.
Sources (3)
- PHOTO MODULATOR, Death By Audio
- Death By Audio Crossover Fuzz + Photo Modulator Expression Controller, Pedal of the Day, 2025-08-19
- Guitar Pedal X, Guitar Pedal X, 2025-08-20
