Orban OPTIMOD-FM 5500 Operation Manual page 126

3-2
OPERATION

Input meters show the peak input level applied to the 5500's analog or digital
inputs with reference to 0 = digital full-scale. If the input meter's red segment
lights up, you are overdriving the 5500's analog to digital converter, which is a
very common cause of audible distortion.

Gate LED indicates gate activity, lighting when the input audio falls below the
threshold set by the AGC gate threshold control (via the Full Modify screen's
control). When this happens, the AGC's recovery time is slowed to
AGC G
ATE
prevent noise rush-up during low-level passages.
There is also an independent gate for the multiband compressor (3-band
and 5-band). You can only see its action from the Optimod PC Remote
software.

Gain Reduction meters normally show the gain reduction in the multi-band
compressor. Full-scale is 25 dB gain reduction.
When the Five-Band structure is operating, all the meters indicate gain reduc-
tion.
When the Two-Band structure is operating, the Band 1 and 2 meters indicate
gain reduction in the Master and Bass bands, the Band 3 meter indicates the lar-
ger of the actions of the left and right HF enhancers, and the Band 4 and 5 me-
ters indicate left and right HF Limiter gain reductions.
When the 5500 is in stand-alone stereo encoder mode, the Band 4 and 5 meters
show the gain reduction in the left/right overshoot limiter meters. Full scale is 5
dB gain reduction. If the overshoot limiter is turned off, these meters will not il-
luminate. The Band 3, 4, and 5 meters are not used in stand-alone stereo en-
coder mode.

Composite meter shows the output level of the stereo encoder before
the composite output attenuators. The meter's reading is calibrated in
percent modulation.

Multiplex Power meter indicates the action of the ITU412 Multiplex Power
controller. It shows how much the MPX Power Controller has reduced the clipper
drive, thereby reducing the average power in the processed audio. It will show
no gain reduction unless the MPX Power Controller is turned on.
The following meters and indicators do not operate when the 5500 is in stand-alone
stereo encoder mode:

Gate LED indicates gate activity, lighting when the input audio falls below the
threshold set by the multiband gate threshold control (with the Full Modify
screen's 2B G control). When this happens, the multiband compressor's recov-
ATE
ery time slows drastically to prevent noise rush-up during low-level passages.
ORBAN MODEL 5500