AVR 2550 (serv.man17) - Harman Kardon Audio User Guide / Operation Manual. Page 25

OPERATION  25

PCM Audio Playback
PCM (Pulse Code Modulation) is the non- com-
pressed digital audio system used for compact
discs, Non-Dolby Digital/DTS Laserdiscs and some
special PCM encoded DVDs. The digital circuits in
the AVR 2550 are capable of high quality digital-
to-analog decoding, and they may be connected
directly to the digital audio output of your
CD/DVD or LD player (LD only for PCM or DTS
programs, for Dolby Digital laser discs an RF
adapter is needed, see ”Dolby Digital” above).

Connections may be made to the Optical or
Coaxial inputs 

L9 on the rear panel.

To listen to a PCM digital source, first select the
input for the desired source (e.g., CD) to feed its
video signal (if any) to the TV monitor and to
provide its analog audio signal for recording.
Next press the Digital Select button Ò

F

and then use the 

⁄

¤

buttons 

C on the

remote, or the Selector buttons 5 on the front
panel, until the desired choice appears in the
Main Information Display M, then press the
Set button Ó

E to confirm the choice.

When a PCM source is playing, the PCM indica-
tor A will light. During PCM playback you may
select any surround mode as described on pages
23 and 24 except Dolby Digital or DTS.

To utilize either digital mode you must have
properly connected a digital source to the 
AVR 2550. Connect the digital outputs from DVD
players, HDTV receivers, satellite systems or CD
players to the Optical or Coaxial inputs on the
rear panel 

L9. In order to provide a backup

signal and a source for analog stereo recording,
the analog outputs provided on digital source
equipment should also be connected to their
appropriate inputs on the AVR 2550 rear panel
(e.g., connect the analog stereo audio output
from a DVD to the DVD inputs 

5 on the rear

panel when you connect the source’s digital 
outputs).

When playing a digital source such as DVD, first
select its input using the remote or front panel
controls as outlined in this manual in order to
feed its video signal (if any) to the TV monitor
and to provide its analog audio signal for record-
ing. When the digital input appropriate with the
DVD player is not selected automatically (due to
the input settings made earlier during the system
configuration, see page 17), select the digital
source by pressing the Digital Input Selector
button 

F Ò and then using the 

⁄

/

¤

buttons

C on the remote or the Selector buttons 5
on the front panel to choose any of the
OPTICAL

or COAXIAL inputs, as they

appear in the Main Information Display M
and Display Indicators BE. When the digital
source is playing, the AVR 2550 will automatical-
ly detect whether it is a multichannel Dolby
Digital, DTS source or a conventional PCM signal,
which is the standard output from CD players. A
Bitstream Indicator A will light in the Main
Information Display Ú to confirm that the
digital signal is Dolby Digital, DTS or PCM.
Note that a digital input (e.g. coaxial) remains
associated with any analog input (e.g. DVD) as
soon as it is selected, thus the digital input need
not be re-selected each time the appropriate
input choice (e.g. DVD) is made.

When a digital source is playing, the AVR 2550
senses the type of bitstream data that is present.
Using this information, the correct surround mode
will automatically be selected. For example, DTS
bitstreams will cause the unit to switch to DTS
decoding, and Dolby Digital bitstreams will enable
Dolby Digital decoding. When the unit senses
PCM data, from CDs and LDs and some music
DVDs or certain tracks on normal DVDs, it will
allow the appropriate surround mode to be
selected manually. Since the range of available
surround modes depends on the type of digital
data that is present, the AVR 2550 uses a variety
of indicators to let you know what type of signal
is present. This will help you to understand the
choice of modes and the input channels recorded
on the disc.

When a digital source is playing, a Bitstream
Indicator A will light to show which type of
signal is playing:

: When the DOLBY D indicator lights, a

Dolby Digital bitstream is being received.
Depending on the audio track selected on the
source player and number of channels on the
disc, different surround modes are possible. Note
that only one channel without subwoofer, called
”1.0” audio, or all five channels with subwoofer
(”5.1” audio) or all steps between can be record-
ed on digitally surround encoded audio tracks
(see NOTE below). With all those tracks, except
”2.0” audio, only the Dolby Digital and VMAx
modes are available. When the Dolby Digital sig-
nal is only two channel (”2.0”) these two chan-
nels (l and r) often contain Pro Logic surround
informations. With those tracks the AVR 2550
automatically switches to the Dolby Pro Logic II
Movie mode (in addition to the Dolby Digital
mode), but you may also select the Vmax mode.
When the D.D. 2.0 signal contains no Pro Logic
information, the pure Dolby Digital mode will be
selected automatically, but you may also select
any Pro Logic II mode (only Music or Emulation
should be used then) or any Vmax mode.

D T S

: When the DTS indicator lights, a DTS bit-

stream is being received. When the unit senses
this type of data, only the DTS mode may be used.

P C M

: When the PCM indicator lights, a standard

Pulse Code Modulation, or PCM, signal is being
received. This is the type of digital audio used by
conventional compact disc and laser disc record-
ings. When a PCM bitstream is present, all modes
except Dolby Digital and DTS are available. Note
that the PCM signal format can be selected on the
DVD player with any audio track, even with Dolby
Digital tracks (but not with Dolby Digital decod-
ing). So, if selected, even ”2.0” D.D. audio tracks
can be played with all surround modes, also with
the most effective Logic 7.