Introduction To Processing; Some Audio Processing Concepts - Orban OPTIMOD-FM 5500 Operation Manual

OPTIMOD-FM DIGITAL

AGC meter shows the gain reduction of the slow two-band AGC processing that
precedes the multi-band compressor. Full-scale is 25 dB gain reduction. You can
switch the meter so that it reads the gain reduction of the Master (above-200
Hz) band, the Bass (below-200Hz) band, or the difference between the gain re-
ductions in the Master and Bass bands.
The latter reading is useful for assessing the dynamic bass equalization
that the AGC produces, and it helps you set the AGC BASS COUPLING
control.
5500 PC Remote software provides meters for both AGC bands.

HF Enhance meter only appears in Two-Band mode and uses the array ordinar-
ily dedicated to indicating B3 gain reduction. The HF E
the amount of HF boost provided by the dynamic, program-adaptive high fre-
quency enhancer located in the Equalization section. Calibration is in relative
units because the amount of enhancement (in dB) depends on frequency. Be-
cause the left and right HF enhancers are independent, we have programmed
this meter so that it reads the larger of the left and right HF enhancement.
The 5500's HF enhancer operates in both Two-Band and Five-Band modes
and in the 5500 PC Remote software is metered in both modes. On the
unit's front panel, there are not enough arrays to meter the HF enhancer
and Five-Band gain reduction simultaneously.
On the 5500's display, the HF Enhancer reads upside down compared to
PC Remote. This is to avoid constantly lighting the red segment at the
bottom of the meter. (Red indicates overload when the meter is indicat-
ing gain reduction.)

HF Limiter meter only appears in Two-Band mode and uses the arrays dedicated
to indicating B4 and B5 gain reduction in Five-Band mode.

Introduction to Processing

Some Audio Processing Concepts

Reducing the peak-to-average ratio of the audio increases loudness. If peaks are re-
duced, the average level can be increased within the permitted modulation limits.
The effectiveness with which this can be accomplished without introducing objec-
tionable side effects (such as pumping or intermodulation distortion) is the single
best measure of audio processing effectiveness.
Compression reduces the difference in level between the soft and loud sounds to
make more efficient use of permitted peak level limits, resulting in a subjective in-
crease in the loudness of soft sounds. It cannot make loud sounds seem louder.
Compression reduces dynamic range relatively slowly in a manner similar to riding
the gain: Limiting and clipping, on the other hand, reduce the short-term peak-to-
average ratio of the audio.
Limiting increases audio density. Increasing density can make loud sounds seem
louder, but can also result in an unattractive busier, flatter, or denser sound. It is im-
meter indicates
NHANCE
3-3
OPERATION