Auotmatic Gain Control (AGC)

P202 adjusts the AGC response. This should be turned fully counter-clockwise to achieve the original design response. Adjusting this clockwise will increase the GAIN level but will also result in more clipping when the resonance is turned up.

1V/Octave Tracking Turn P104 fully counter-clockwise and then apply 7 full clockwise turns Set [RANGE] to ‘HI’ Patch [BAND] to [IN] Set the [IN] level control to maximum Set [Q] to maximum Monitor [LO] Apply 0.0V to [1V/OCTAVE] Adjust [FREQUENCY] to produce an output running at 110Hz Apply 3.0V to [1V/OCTAVE] Slightly adjust P104 clockwise to approach 880Hz Repeat steps (7) to (10) for an accurate transpose of 3 octaves

 

The CGS508 are factory adjusted and should not need further calibration.

Functional Testing

1. Apply a sawtooth wave to [AGC]. Manually turning the [FREQUENCY] pot and the [Q] pot should produce filter sweeps of varying "Q"s and frequency ranges at the [LO], [HI], and [BAND] pass outputs.

2. Using a 0-5VDC control voltage, test the VC-F and VC-Q functions. Note the processing input on the [VC-F] as well as the calibrated [1V/octave] input.

3. Apply a signal to the manual gain input [IN], and turn up the manual gain pot. This input differs from [AGC] in that the gain of [AGC] is automatically controlled for use with increasing Q. As Q is increased, the gain of [AGC] is decreased to compensate for the peaked response of the high Q filter. Note the difference by first applying a signal to [IN] and increasing and decreasing the [Q], then applying a signal to [AGC] varying the [Q].

4. The [NOTCH] output should produce a phasing type sound if a sawtooth wave or a noise signal is applied to the filter input, the [Q] is low, and the frequency is swept.

5. Apply a pulse source into the [TRIG] input while listening to the [BAND] output. A percussive timbre should be present which can be changed dramatically by changing the filter frequency and increasing the Q