HARM ENGINE - square wave harmonics or digital sonic filth in +/- 5 octaves with 3rds and 5ths
The HARM ENGINE is based on the CIRCUITBENDERS 'Harmonic Engine' PCBs, it's "a clone of the E&MM Harmonic Generator. This was a project by Paul Williams, published in Electronics & Music Maker magazine way back in 1981. The circuit uses a 4046 Phased Locked Loop (PLL) to generate a squarewave output at harmonic intervals to the frequency of the input signal. The squarewave can be set to +/- three [5 + a chaos noise mode in the METSÄÄN version] octaves, and can also produce 3rd or 5th harmonies. That's the theory anyway. In practice this only works reliably if you use very basic waveforms at the input. If you use anything else, then everything very quickly descends into a beautiful kind of chaos, with all kinds of bizarre gurgling digital squeaks and squeals vomiting forth. Its especially effective with percussion sounds, converting each hit into some kind of warped electronic splatter." The controls from top left to right are: SENSITIVITY - controlling the level at which the harmonics will be played. Turning the pot clockwise increases the gain of the signal (it also boost with a slight distortion, the DRY signal). In higher settings, the squarewave harmonics can form a modulated drone voice. Activity of the HARM ENGINE is indicated by a green LED, that turns on when harmonics are produced. 3RD/5TH - the 3 position toggle switch activates the corresponding detuning. The middle position is neutral. MIX - is a blending function to dial in the balance between DRY and HARM signal. If something is plugged into the DRY and HARM outputs on the rear of the machine, MIX stops working, because the signal is split before. OCTAVE - with a 12 position rotary switch, +/- 5 octaves are selected, 12o'clock is neutral and 6o'clock is the chaos/noise mode. TRUE BYPASS - The footswitch is configured for true bypass and has a pink indicator LED inside the machine, the glow can be seen through the vent grills in the enclosure. Build into a scavenged high voltage converter housing made from plastique painted in the 'burned out industry' camo pattern in matte black and chrome. Hand made by grm for METSÄÄN.
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