Doepfer's A-101-8 Photo Phasing module is modeled after Schulte's cult Compact Phasing A phaser effect from the 1970s. This 8-stage Phase shifter was already used by Tangerine Dream and Klaus Schulze back then and is, in a way, a must-have for the own Eurorack system for followers of this era. The actual circuitry is identical to the historical model. The difference in the A-101-8 is that LEDs are used instead of small incandescent lamps.
Equipment and use:
The eight photoresistors and LEDs are located inside a lightproof housing; in addition, the circuit boards of the module are made of opaque material to largely shield any interfering light from neighboring modules or the backplane. In contrast to the original, no LFO is integrated, but any control voltage (S&H, ADSR, LFO, velocity...) can be used to modulate the phasing offset; the modulation depth (feedback) is manually adjustable. The Mix control fades smoothly from the unprocessed to the processed signal, but depending on the position of the Feedback control and the use of the outputs, the dry signal may already be affected by the Feedback function.
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