Optimod-Surround 8685 V1.0 Operating Manual - Orban

2-26
INSTALLATION ORBAN MODEL 8685
the typical indications with program material on a VU meter versus the higher
indications on a PPM.
A) LOCATE to RECALL/IMPORT.
B) Turn the knob until ROCK MEDIUM appears in the lower line of the display.
C) Press the ENTER button to recall the preset.
D) Verify that the 8685’s SURROUND EXTERNAL AGC control is set to NO.
Refer to step 2 on page 2-20.
E) LOCATE to INPUT/OUTPUT > INPUT > SURROUND INPUT REFERENCE (VU or PPM, depending
on which metering system you use).
F) Calibrate using tone.
If your facility does not use a formal reference level and/or if the link to
the 8685’s input uses J.17 preemphasis (which is only available for the 2.0
input; see step 5 on page 2-23):
• To calibrate using tone, perform steps (a) and (b) below.
• To calibrate using program material, skip to step (G) on page 2-26.
a) If you are not using a studio level controller, feed a 400 Hz tone into the Lf
and Rf channels of the 8685 through your console at your normal program
line-up level (typically 0 VU if your console uses VU meters). Do not drive
any other channels.
b) If you are using a studio level controller that performs an AGC function,
feed a 400 Hz tone at your normal program level into its Lf and Rf channels
and adjust the studio level controller for normal operation.
c) Adjust the 8685’s SURROUND INPUT REFERENCE (VU or PPM) control to make
the 8685’s AGC meter indicate 10 dB gain reduction.
d) Skip to step (H).
G) Calibrate using program.
[Skip this step if you are using Tone to calibrate the 8685 to your standard
studio level—see step (F) above.]
a) Feed normal program material to the 8685
Play program material from your studio, peaking at the level to which
you normally peak program material (typically 0VU if your console uses
VU meters).
b) Adjust the SURROUND INPUT REFERENCE (VU or PPM) control to make the
8685’s AGC meters indicate an average of 10 dB gain reduction when the
console’s VU meter or PPM is peaking at its normal level.
If the AGC gain reduction meter averages less than 10 dB gain reduction
(higher on the meter), re-adjust the SURROUND INPUT REFERENCE (VU or
PPM) to a lower level.