What Is a Sound Activated Cathode?

Mal Baxter
Mal Baxter
Man holding computer
Man holding computer
Man holding computer

A sound activated cathode refers to a type of lighting system popular with lighting designers and computer case modifiers, or modders, consisting of a cathode ray lighting tube commonly lit in bright, neon-like colors. These lights are designed to activate or flash with the rhythm of music, often with a sensitivity adjustment to control the rate of pulse. Units are sometimes run with a step-up transformer, on direct current (DC) of typically 12 volts (V), and connected with pin-and-socket style connectors. Sold in kits, they may be accompanied by inverters that limit amperage and control activation sensitivity and power to override sound control.

Cold cathode fluorescent (CCFL) tubes operate on a principle of cathode ray lighting; they employ a type of light ray generated in a vacuum tube by applying an electrical discharge to a gas, commonly mercury vapor. Excitation of the plasma arc emits ultraviolet (UV) radiation, which glows on the phosphorescent surface of the glass. Sound activated cathode tubes can be sheathed in tinted sleeving to increase the color effect. They can be mounted with ties or hook and loop strips.

Compared with other types of lighting, cold cathodes require very little power consumption. As a result, they produce very little heat, which makes sound activated cathode lights ideal for placement in cases or interiors. These lights frequently have a lifespan of about 15,000 hours, which translates to a couple of years of continuous use.

Sensitivity to sound and music beats makes them a striking element for people seeking to create a dramatic lighting effect or mood. CCFLs can enhance darker environments and add excitement and atmosphere as well as draw attention to the emotional effects of music. Sound activated cathode fixtures are sometimes integrated with separate sound activated modules that provide characteristic sound responses. These modules can also work with light-emitting diode (LED) components. They are often easily installed with simple connectors.

Distinctive and bright, sound activated cathode lights may feature very sensitive responses to sound and add a lot of fun to their surroundings. Generally affordable, they usually warm up to their fullest brightness a couple of hours after their initial activation. Colors may include green, purple, blue, orange, white, and red, although the nature of this lighting makes red a more difficult color to replicate, and the true red cathode all the more desirable among enthusiasts. Products can include cathode-lit fan kits to replace computer components, single or multitube sets, and various adapters and switches.

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Discussion Comments


@everetra - That’s awesome. I don’t have any major Christmas light shows where I live, but I notice that some drivers have been putting on light shows of their own.

I’ve seen some cars driving around with these soft blue neon lights mounted to the underside of the car. At night they look kind of cool. I don’t know if they’re meant to be for show, or just illumination, or both.

However, I’d be scared that the cops might stop me if I rode around with those things. But I don't know for sure whether a car neon light is illegal or not.


Every Christmas the biggest church in our town puts on a big extravaganza of Christmas lights and decorations, so huge in fact that people come from nearby towns to view the event.

I think they use something on the order of one million lights.

Anyway, they play music and lights beat to the rhythm of the music, often in different colors. It’s a colorful and brilliant spectacle. I never knew how they were doing that, but I bet they’re using these sound activated cold cathode bulbs to do the effect.

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