Read Harman Kardon AVR 85 (serv.man3) Service Manual online
IV. TECHNICAL DESCRIPTION
This product is a “Dolby Digital (AC-3)” decoder. By connecting this product with a Dolby digital compatible component such
as a DVD player or DBS tuner, it will be capable of 5.1 CH (Front L/R, Rear L/R, Center and Sub-woofer) play.
This product is composed of approximately of 5 blocks including the AC-3 decoder & DAC block (P604), crossover block
(PC04), power supply block (P704), volume control block (PE04) and front key input block (PU04).
V. SIGNAL AND CIRCUIT DESCRIPTION
OPT/COAX (AC-3/PCM input)
This signal is based on an additional format for transmitting the AC-3 data through the conventional digital audio interface
(SPDIF). This SPDIF contains the compressed data for AC-3, instead of PCM Audio data. Similarly to the case of ROM data,
whether the data is audio or non-audio is identified according to the status in the signal. This signal can be output from a DVD
player, etc.
DAI (Digital Audio Interface) Receiver
This circuit extracts various clock and data signals from the signal input in the SPDIF format.
AC-3 Decoder DSP
This circuit generates the 6-channel data (Front L/R, Rear L/R, Center and LFE) based on the data output from the DAI, and
outputs the 6-channel data to the DAC as 3 sets of 2-channel data.
Crossover
This circuit consists of 100Hz HPF for each channel, 100Hz LPF for sub-woofer channel, and mixing for sub-woofer output.
Depending on the speaker mode setting, frequencies of this circuit will be changed.
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Harman Kardon
Dolby Digital Audio/Video Receiver
AVR75/85
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