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INTRODUCTION
ORBAN Model 6200
If you are encoding at a sample rate lower than 44.1kHz, set the 6200's lowpass filter
cutoff frequency to approximately 45% of the encoder's sample frequency. You may
have to read your encoder documentation carefully to determine the sample frequency,
because this bears no relationship to the output bit rate after lossy audio compression by
the encoder. The encoder may do a sample rate conversion on its input before encoding.
Using the 6200 in Non-Streaming Applications, to Prepare
Audio Files for Download
The 6200's inputs and outputs will be connected the same way that they are for stream-
ing applications. There are two scenarios. In the first, you pass external program material
through the 6200 and then record the processed program onto your hard disk. This can be
done with any sound card having a digital input. The resultant files are then processed
offline through the appropriate encoding application(s).
The second scenario supports processing of files already existing on the computer's hard
disk or other storage device. It requires a sound card capable of full duplex operation,
such that its digital input and output can be used simultaneously. Few consumer-grade
sound cards support this mode of operation, but most cards designed for audio produc-
tion will do so. The processor is then used in loop-through mode, accepting unprocessed
playback from the computer and emitting processed audio, which is then recorded as a
separate file through the sound card's input onto the hard disk.
Decoder Headroom
It is possible that highly processed audio (like the output of the 6200) will cause certain
decoders to overshoot and clip, even if no clipping occurs at the encode side. This is a
design defect in the decoder. Nevertheless, you should carefully test and qualify the lat-
est decoding software (and possibly hardware) that complements the encoding algorithm
you are using. If you observe clipping or other distortion, you will have to reduce the
6200's output level until the decoder no longer distorts.
You should periodically re-test suspect decoders and hardware as new revisions become
available to ascertain when (or if) the problem has been fixed.
Loudness
You can expect a large increase in loudness from 6200 processing by comparison to un-
processed audio. (An exception is recently mastered CDs, which may have already been
aggressively processed for loudness when they were mastered.) In radio broadcasting, it
is generally believed that loudness relative to other stations attracts an audience that per-
ceives the station as being more powerful than its competition. We expect that the same
subliminal psychology will hold in webcasting too.
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