2-52
INSTALLATION
ORBAN MODEL 1101
•
Be sure that the output meters for the processor mixer and Direct Mixer never go
into the red. If they do, turn down the input attenuator(s) connected to the sig-
nal causing the overload.
•
If you are running Windows 7 or Serve 2008 and are using Optimod-PC’s WAVE
I/O, see instructions on installing the Windows SRC hotfix (step 18 on page 2-16).
Audible noise in processed audio
(See also “RFI, Hums, Clicks, or Buzzes” on page 2-50.)
•
Excessive compression will always exaggerate noise in the source material.
OPTIMOD-PC reduces this problem with its compressor gate, which freezes the
gain of the AGC and compressor systems whenever the input noise drops below a
level set by the Gate Threshold control, preventing noise below this level from
being further increased.
There are two independent silence gates in each processing channel of the 1101.
The first affects the AGC and the second affects the Multiband Compressor. Each
has its own threshold control. (See Mb Gate on page 3-59.)
In sound for picture, the setting of the Gate Threshold control is quite critical if
you want the processing to be undetectable to the audience. If this control is set
too low, then the 1101 will pump up quiet sounds like ambiance and underscor-
ing to unnaturally high levels. Refer to Section 3 of this manual for a further dis-
cussion.
•
If you are using OPTIMOD-PC's analog input, the overall noise performance of
the system is usually limited by the overload-to-noise ratio of the analog-to-
digital converter used by OPTIMOD-PC to digitize the input. (This ratio is better
than 100dB.)
•
It is important to specify the
A
NALOG
I
NPUT
R
EFERENCE
L
EVEL
correctly (see step 1
on page 2-35). You should specify the level as the highest peak level that
OPTIMOD-PC will receive under normal operation. If, in an attempt to build in a
“safety factor” or increase headroom, you specify a higher level than this, every
1dB of extra headroom that you gain will increase OPTIMOD-PC's noise floor by
1dB.
•
OPTIMOD-PC's AES3 input is capable of receiving words of up to 24 bits although
the dynamic range of its input sample rate converters limits the worst-case dy-
namic range to 20 bits. A 20-bit word has a dynamic range of approximately
120dB. OPTIMOD-PC's digital input will thus never limit the unit's noise perform-
ance even with very high amounts of compression.
•
In digital radio applications, if an analog studio-to-transmitter link (STL) is used
to pass unprocessed audio to OPTIMOD-PC, the STL's noise level can severely limit
the overall noise performance of the system because compression in OPTIMOD-
PC can exaggerate the STL noise. For example, the overload-to-noise ratio of a
Summary of Contents for Optimod-PC 1101
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