This article is about electronic sound-responsive lighting devices. For historical optical music instruments, see Color organ. For biological light organs, see bioluminescence.
A light organ is an electronic device that automatically converts an audio signal (such as music) into rhythmic light effects. Light organs became popular in the 1970s as lighting effects for discotheques and dance parties. During this period, home entertainment manufacturer Morse-Electrophonic produced stereo systems with built-in light organ displays, such as their "Stereo Bar" model. The multicolored lights would pulsate to the beat of the music.
The circuit of a light organ separates the audio signal into frequency bands and controls the light channels according to the average level of each band using dimmers. A typical party light organ of the 1970s featured three spotlights—red, green, and blue—responding to bass, medium, and high frequencies respectively.
Due to their simple structure, light organs became popular DIY projects for electronics hobbyists in the 1970s and can still be found for sale on the internet.
History
1969 SWTPC advertisement for the "Psychedelia" color organ
Commercial kits emerged in the mid-1960s. Southwest Technical Products Corporation (SWTPC) offered early examples, including the single-channel "Sonolite" (1968), capable of controlling 500 watts of lighting, and the more sophisticated "Psychedelia" series (1969–1972), featuring four-channel systems with an 800-watt capacity per channel.[1][2][3] SWTPC's later "Psychedelia II" introduced digital sampling techniques as an alternative to traditional analog filters, switching rapidly between channels to create different visual effects.[3]
In 1971, the Rickenbacker guitar company offered their 331LS "Lightshow" model (and matching bass, model 4005LS). The body contained a three-channel light organ with a dimmer, where each channel corresponded to the pitch of the strings being played. The soundboard on these models was replaced with thin Plexiglas cutouts over a translucentmoirediffraction material.[4][5]
A notable commercial example was Heathkit's TD-1006 kit (1975), which departed from random light arrangements by using a geometric star-burst pattern of 140 lights arranged in alternating color circles.[6] The unit used four bandpass filters at 80, 350, 1000, and 3000 Hz to control red, blue, green, and amber lights respectively. This created visual effects that appeared to pulsate, explode, and pinwheel with the music.[7][8]
With the widespread adoption of affordable PCs, some hobbyists began experimenting with using computers for frequency analysis instead of analog filters.
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