“The A/DA Final Phase was originally designed by Lee Powell in 1977. It used Vactec opto-coupled resistors and a very unique phase shift circuit along with a “one knob” distortion that keeps the level constant with different amounts of distortion. When David heard it, he was intrigued by the depth of the phasing. The original Final Phase design was shipped for only a few months and replaced with a more stable and easier design manufacture using switched capacitors instead of the Vactecs in 1978. This preserved the “high-Q” sound of the phaser and broadened the sweep range.”
“The A/DA Final Phase is a 10-stage phase shifter with distortion. It also has a random sweep modulator that modulates the sine wave, speeding it up and slowing it down and adding sine waves so it sounds like a random pattern.”
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