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OPTIMOD 6300 DIGITAL
Section 5
Troubleshooting
Problems and Potential Solutions
Always verify that the problem is not the source material being fed to the 6300, or
in other parts of the system.
RFI, Hum, Clicks, or Buzzes
For good RFI resistance, always use balanced inputs and outputs.
Review the information on grounding on page 2-8. The 6300 has been designed
with very substantial RFI suppression on its analog and digital input and output
ports, and on the AC line input. It will usually operate adjacent to high-powered
transmitters without difficulty. In the most unusual circumstances, it may be neces-
sary to reposition the unit to reduce RF interference, and/or to reposition its input
and output cables to reduce RF pickup on their shields.
The AES/EBU inputs and output are transformer-coupled and have very good resis-
tance to RFI. If you have RFI problems and are using analog connections on either
the input or output, using digital connections will almost certainly eliminate the RFI.
Poor Peak Modulation Control
The 6300 ordinarily controls peak modulation to an accuracy of ±1% when operated
with 48 kHz output sample rate. As explained in Section 1, output sample rate con-
version will slightly compromise this control because the peak control occurs with
reference to individual sample values at 48 kHz. The converted samples no longer
have the same peak values as the 48 kHz samples; some values can be slightly higher.
However, the overshoot of the converted signal almost never exceeds 0.5dB and is
therefore not a significant problem.
Using the analog output will cause similar amounts of overshoot because the sam-
ples in the transmitter are not synchronous with the peak-controlled samples in the
6300. Further, analog connections can cause analog-domain overshoot if the connec-
tion is not phase linear and has a –3dB low-frequency cutoff of greater than 0.15Hz.
Audible Distortion
Make sure that the problem can be observed on more than one monitoring system
and at several locations.
TROUBLESHOOTING
5-1
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Table of Contents
Troubleshooting
