Instruction manual

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Input Level

Calibration

NOTE: This portion of 708 calibration must follow the preceding

Crosstalk Trim procedure directly.

1. Re-apply 400Hz to both channels and monitor the filter buffer stage

at R128 and R135, just as described at the beginning of this

Procedure.

2. Turn the O’SHOOT COMP. switch to the IN position.

3. Make no changes to the 708 INPUT GAIN controls. Note that as the

output level of the Audio Generator is increased, the 9-volt p-p

waveforms will clip, or flatten, top and bottom. Carefully, adjust

the output level of the Audio Generator to a point where the

flattening is scarcely visible. As the O’SHOOT COMP. switch is

switched between IN and OUT, there should be a just-perceptible

change in the amplitude of the waveform(s) as the clipping circuit is

biased into, and out of, operation. This Audio Generator output

level setting represents the 100%-modulation level as applied to the

708 PROGRAM LINE INPUT terminals.

4. With the front-panel meter monitoring the left-channel input, L,

adjust R45 for a half-brightness indication of the 0dB, LED.

5. Step the meter to monitor the right-channel input, R, and adjust

R46 for a half-brightness indication of the 0dB LED.

6. Verify that L+R metering indicates 0dB with the LED at full

brightness, and that nothing shows in the L–R position.

Output Level

Calibration

NOTE: This portion of 708 calibration must follow the preceding

Input Level Calibration procedure directly.

1. Set the MODE switch to STEREO and turn the PILOT switch ON.

2. With the 400Hz, 100%-modulation input signals applied, turn the

front-panel COMPOSITE PROCESSING control fully clockwise to

the +3dB marking.

3. With the Modulation Monitor connected to the COMPOSITE

OUTPUT of the 708, and with the Mod-Monitor set to read Total

Modulation in its peak-responding mode, adjust the OUTPUT LEVEL

control of the 708 for a 100% Mod-Monitor reading.

4. Switch the Mod-Monitor to measure the 19kHz stereo pilot

injection level, and adjust the 708 front-panel PILOT INJ. control for

a 10% reading.

5. If necessary, repeat Steps 3 and 4 to secure simultaneous 100%

Total Mod. and 10% Pilot readings.

6. With 708 front-panel metering switched to MPX, adjust R47 for a

0dB indication.

7. With 708 metering switched to PILOT, adjust R48 for a 0dB

indication.