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Tempco Resistors
My version of the 20-pole-Phaser was designed with a 560 Ohm Tempco Resistor for Temperature compensation of the 1V/Octave tracking.
(The Tau "Pipe" Phaser used a 1.87 kOhm Tempco Resistor.)
You can use a 1 kOhm Tempco Resistor, which is a much more common value, if you also change two other component values.
This picture shows what you have to change. (Or click on image to enlarge.)
Calibration
1. Pitch trimmer setting. (I guess No input signal is needed to do this, or Yes?)
First set:
a. The external “Pitch” pot to middle position (?)
b. The external “Modulation Depth (Oscil. Level)” pot to maximum (cw) position (?)
c. The external “Modulation Rate (Sweep Rate)” pot to lowest (ccw) position (?)
Then adjust the pitch trimmer for the most pleasant sweep sound.
2. Resonance trimmer setting. (Is an input signal necessary and if yes, any suggested frequency?)
First set:
a. The “Resonance” trimmer to maximum (cw).
b. The external “Resonance” pot to maximum.
c. The nice/screaming oscillation “switch” (if installed), to the “off” (nice) position.
Then reduce “Resonance” trimmer until you like it
Frontpanel connections:
Pots:
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