HD621 HDMI Audio Processor
User Guide
6
The HD621 accepts a maximum input sample rate of
192kHz.
If possible, set the output sample rate of your source to
match the sample rate of the content being played.
How sources and displays behave
The HDMI interconnection system uses handshaking to
establish a dialogue between a source and a display. Typically
the display signals its capabilities to the source, and the source
then generates the highest quality signal it can to meet those
capabilities. This is why, when you first activate a system, there
may be a succession of blank and blue screens while the two
components work out how to communicate with each other at
the highest level of quality common to both.
When the HD621 is added to the system, it reads the display
capabilities and passes them to the source, but at the same
time adds a description of its own enhanced audio capabilities.
Essentially, the HD621 tells a source what audio it is capable
of handling (or is configured to handle), but it is left up to the
source how it satisfies those capabilities. For example, if you
configure the HD621 for 2-channel audio but also specify that
it can handle bitstreams, you will need to configure the source
as to whether it should send a 2-channel PCM track on the disc
or a 5.1 DTS bitstream, if both are possible.
The HD621 also has a “receiver” mode, which it will
enter automatically if the display device is switched off or
disconnected. This allows music to play or continue to play
without a display. It may take a few seconds while the units
handshake to establish this mode. It may also take a few
seconds to re-establish communications if the display is
reactivated, because of the HDMI handshaking procedure. Also
see the Operational Notes section at the end of this guide.
System defaults
By default, the unit is set to work with Meridian Surround
Controllers and DSP Loudspeakers, and to enhance up to
6-channel PCM inputs. If they have not been decoded in
the player or source (decoding in the source is the preferred
configuration), Dolby Digital, DTS and AAC bitstreams are
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passed through untouched. If you are using the HD621 with
other equipment that does not support Meridian’s MHR, then
you will need to run the Meridian Configuration Program to
disable MHR.
To reconfigure the HD621 from its standard defaults, you will
need to connect a Windows computer via the RS232 connector
and use the Meridian Configuration Program to set it up. See
below for details.
Controlling the HD621
The HD621 can be controlled via Meridian Comms, from the
front panel and via RS232 serial commands.
The front panel allows you to step through the active inputs. An
input that has been disabled will not be included as you step
through. No other functions are accessible from the front panel.
RS232 can be used to control the HD621 in conjunction with
a home automation system. The unit responds to standard
Meridian commands to select named sources, enter Standby
and other functions. An RS232 command table is available on
request.
