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YuSynth Quad LFO Module
The quadrature LFO is a special module that was not found on many modular synthesizers back in 1970s. Mostly, only companies like Polyfusion, Buchla or Serge would propose such a weird LFO.
Basically, it is a sinewave LFO with four outputs which are running at the same rate but are phase shifted by increment of 90°. That is, the first output has a shift of 0°, the second 90°, the third 180° and the fourth 270°.