User-Friendly Interface; Absolute Control Of Peak Modulation - Orban Optimod-FM 8300 Operating Manual

1-2
INTRODUCTION

User-Friendly Interface

Absolute Control of Peak Modulation

OPTIMOD-FM was designed to deliver a high quality sound while simultaneously in-
creasing the average modulation of the channel substantially beyond that achiev-
able by "recording studio"-style compressors and limiters. Because such processing
can exaggerate flaws in the source material, it is very important that the source
audio be as clean as possible.
For best results, feed OPTIMOD-FM unprocessed audio. No other audio process-
ing is necessary or desirable.
If you wish to place level protection prior to your studio / transmitter link (STL), use
an Orban studio level control system expressly designed for this purpose. (At the
time of this writing, this is the Orban 8200ST OPTIMOD-Studio Compressor / Limiter /
HF Limiter / Clipper.) The 8200ST can be adjusted so that it substitutes for the broad-
band AGC circuitry in OPTIMOD-FM, which is then defeated.

An LCD and full-time LED meters make setup, adjustment and programming
of OPTIMOD-FM easy — you can always see the metering while you're adjusting
the processor. Navigation is by dedicated buttons, soft buttons (whose functions
are context-sensitive), and a large rotary knob. The LEDs show all metering func-
tions of the processing structure (Two-Band or Five-Band) in use.

The 8300 provides universal transmitter protection and audio processing
for FM broadcast. It can be configured to interface ideally with any commonly
found transmission system in the world.

The 8300 provides pre-emphasis limiting for the two standard pre-emphasis
curves of 50s and 75s. Its pre-emphasis control is seldom audibly apparent,
producing a clean, open sound with subjective brightness matching the original
program.

By integrating the stereo encoder with the audio processing, the 8300 elimi-
nates the overshoot problems that waste valuable modulation in traditional ex-
ternal encoders. The stereo encoder has two outputs with independent level
controls, each capable of driving 7in parallel with 47,000pF, (100ft / 30m of
coaxial cable).

The 8300 prevents aliasing distortion in subsequent stereo encoders or transmis-
sion links by providing bandwidth-limiting and overshoot-compensated 15
kHz low-pass filters ahead of the 8300's audio outputs and stereo encoder.

Anti-aliased clippers running at 256 kHz sample rate prevent any trace of
"digital clipper" sound.
ORBAN MODEL 8300