Orban OPTIMOD-AM 9300, Руководство по эксплуатации

Страница: 208 / 242

6-8
TECHNICAL DATA ORBAN MODEL 9300
verter IC107. IC105A and associated components comprise a servo amp to cor-
rectly DC-bias the signal feeding the A/D converter. R137-139, C109, C110
make an attenuator / RC filter necessary to filter high frequency energy that
would otherwise cause aliasing distortion in the A/D converter.
The corresponding right channel circuitry is functionally identical to that just
described.
IC100, 102 are socketed for easy field replacement. All other circuitry is sur-
face-mounted and is not field-replaceable.
Stereo Analog-to-Digital (A/D) Converter
Located on input/output/DSP board
The A/D converter, IC107, is a stereo 24-bit sigma-delta converter. (This is a sur-
face-mount part and is not field-replaceable,)
The A/D oversamples the audio, applies noise shaping, and emits a bitstream at
64 kHz sample rate. The 9300 decimates this to 32 kHz using a high-quality syn-
chronous sample rate converter realized in DSP. The 9300’s audio processing op-
erates at a 32 kHz sample rate and multiples thereof.
Digital Input Receiver and Sample Rate Converter (SRC)
Located on input/output/DSP board
The receiver IC300 accepts digital audio signals using the AES3 interface format
(AES3-1992). It applies its output to sample rate converter IC302. This accepts and
sample-rate converts any of the “standard” 32 kHz, 44.1 kHz, 48 kHz, 88.2 kHz,
and 96 kHz rates in addition to any digital audio sample rate within the range of
32 kHz and 96 kHz. The SRC converts the input sample rate to 48 kHz for process-
ing by the DSP.
Receiver IC301 accepts sync signals in either AES11 or word clock formats and
generate a reference sample rate for the 9300’s output sample rate converters.
Relay IC304 determines if the 9300’s sync input will accept AES11 or word clock.
These chips are surface-mounted and not field-replaceable.
Output Circuits
This circuitry interfaces the DSP to the analog and digital audio outputs. The digital
audio from the DSP is transmitted to the digital-to-analog converter (D/A) and out-
put sample rate converter (SRC). The digital-to-analog (D/A) converter converts the
digital audio words generated by the DSP to analog audio. The analog output stag-
es scale and buffer the D/A output signal to drive the analog output XLR connectors
with a low impedance balanced output. The digital output transmitter accepts the
digital audio words from the output sample rate converter (SRC) and transmits them
in AES3-format digital audio signals on the digital output connector.