What is it?
An experimental analogue video mixer that turns sound into colourful visual distortion. Based on the Schele Dirty Video Mixer by experimental electronics artist Gijs Gieskes, this version adds a simple audio-reactive circuit that makes the image respond to music and other sound sources.
The result is a constantly changing mix of colour bleeding, horizontal interference and unexpected glitch patterns. No digital effects or software are needed to create the distortion: it happens directly in the analogue video circuitry.
From experiment to discovery
The project started with building and experimenting with the original dirty video mixer. Changing capacitance around the circuit produced striking changes to the picture, including horizontal tearing and loss of colour. That led to a different question: what would happen if an audio signal could influence the distortion?
After testing different component values and connections, I developed a small audio-controlled modification using a BC550 transistor, a diode, resistors and capacitors. One connection point produced particularly dramatic, colourful results, so I concentrated on refining the response there.
Sound-controlled visuals
Audio signals change the way the mixer distorts the video. Low-frequency tones and rhythmic sounds can produce moving bands, shifting colours and waveform-like patterns across the screen. Changing the frequency or level of the audio can transform the image from subtle colour movement to much more extreme glitch effects.
The circuit is not a conventional audio visualiser. Its behaviour comes from the interaction between the audio-controlled modification and the timing and colour information of an analogue PAL video signal. Much of its appeal is that the results are unpredictable.
Photos
The hardware
At the heart of the project is the original Schele Dirty Video Mixer, with an additional audio modulation circuit built around a BC550 NPN transistor. The modification uses only a small number of inexpensive components and was developed through practical experimentation with a breadboard and an oscilloscope.
The original mixer includes selectable capacitors that alter the video distortion. My additional circuit provides a different effect: sound-responsive colour bleeding and movement, with the character of the image changing as the audio input changes.
Circuit diagram
A circuit diagram of the audio-reactive modification will be added here, showing the component values and its connection to the video mixer. The modification is an experimental addition to Gijs Gieskes' original design.
Built to experiment
This project was never about producing a perfectly controlled video effect. It was about discovering what happens when sound and analogue video circuitry interact, and enjoying the unexpected results along the way.
Built to Experiment. Modified by Curiosity. Designed to Look WOW.
Original design credit
The Schele Dirty Video Mixer was originally designed by Gijs Gieskes. The audio-reactive modulation described here is my experimental modification to that design.