HDMI Audio Processor
Six-input HDMI switch.
HDMI video output.
Extracts up to eight channels of
high-resolution audio from the
HDMI data stream, supplying them
to separate audio-only outputs.
Connects HDMI audio direct to a
Smartlink coaxial digital audio
output (up to 8 channels).
The Meridian HD621 HDMI Audio the HD621 to the display, while enhanced Multichannel Meridian High
Processor extracts the audio signal digital audio is fed to the sound system. The Resolution (MMHR): balanced
from the data stream at the HDMI HD621’s audio outputs connect directly digital audio output via RJ45/Cat
input and provides separate audio to an existing Meridian processor, offering 5 cable (up to 8 channels).
outputs suitable for a Meridian complete and immediate system integration. Up- and down-sampling of digital
surround controller. Internal buffering audio.
and processing improves audio The HD621 includes Meridian’s
Audio FIFO buffering and
quality. It is also a 6-into-1 HDMI video comprehensive FIFO buffering system and
resolution enhancement improves
switch, allowing all your HDMI-based resolution enhancement, based on that used
PCM audio received via HDMI.
components to be fed via a single in the 800 Series. This cleans up incoming
video cable to your display. PCM digital audio signals, removing the Lip-sync control compensates for
timing and other degradations audio suffers latency resulting from external
HDMI (High Definition Multimedia Interface) when combined with video in HDMI. The digital video processing.
connectors are a common sight on HD video audio is clocked into a dual-section buffer Keeps HDMI video signals away
and other equipment. Usually employed to and clocked out again after re-shaping from your audio equipment,
carry digital video, HDMI also carries digital the digital audio waveform structure and minimising signal degradation.
audio. However, having both audio and video re-timing with extremely accurate reference
on the same cable is not always convenient, clocking signals. The result is a significant
nor does it deliver the maximum level of and audible improvement in quality, including Outline specification
quality of which digital multimedia signals are accuracy of stereo and surround imaging and
capable. localisation, as well as overall sonic benefits Form factor
including improved transparency at the high • 1U 19in rack mounting
Digital video signals have traditionally been frequency end. The unit also allows for up-
the bane of those in search of the best audio and down-sampling of digital audio signals, Power
• Internal universal power supply,
quality. They include very high frequency to provide outputs at standard (44.1/48 kHz) 100–250Vac
signals with very fast rise-times and thus or high (88.2/96 kHz) resolution sampling
tend to radiate an enormous spectrum of rates. Connections
harmonics. This unwanted radiation can leak • Power input (IEC connector)
into audio circuits, causing noise and even A configurable audio delay system is built in, • DB9M Sub RS232 serial connector
• BNC and DIN Meridian Comms
disrupting the signals themselves, causing allowing you to ensure that sound is always
• Six HDMI input sockets
muting, interpolation and other effects. In in perfect synchronisation with the picture, • HDMI output
particular, digital video (indeed video of any even if the image is being processed with • 8-channel MMHR digital audio out
sort) can leak into analogue audio circuitry, significant amounts of latency. The HD621 (RJ45)
causing hum, buzz, noise and other unwanted also ensures that the HDMI interface is • 8-channel coax digital audio out (4 x
artifacts. driven correctly, which may result in improved phono)
video as well as audio performance.
The HD621 solves these problems at a Front-panel Indicators
stroke, while allowing all your components The HD621 is housed in an elegant black • Power LED
that deliver video via HDMI a common slimline 1U rack-mount panel for unobtrusive • 6 x HDMI Input LEDs (selected input
destination. A single cable can be run from installation.
HDMI Audio Processor
Front panel SmartLink Output – These four phono HDMI audio processor reclocks PCM digital
sockets each carry a pair of digital audio audio information received via HDMI and
The front panel (see above) simply shows a
channel signals at up to 96 kHz sample rate: re-times it, clocking it into and then out of a
power LED plus six LEDs indicating which
1/2, 3/4. 5/6 and 7/8. These are encrypted FIFO (First In, First Out) buffer system. This
input is currently selected. A manual select
to Meridian High Resolution (MHR) ensures that the audio extracted from the
button allows you to step through the inputs.
specifications when carrying high resolution HDMI stream is of the highest quality.
HDMI carrying both video and audio is not
The rear panel features the following Power input socket, power switch and fuse the best environment for digital audio and
connections (L to R): holder – the power supply accepts a standard the integrity of the audio signal can be
IEC power connector and is a universal compromised, especially as far as timing
RS232 DB-9M Sub connector - this enables voltage type accepting voltages between 100 is concerned, where the rise-time of digital
the processor to be controlled remotely via and 250Vac at 50/60 Hz. audio signal pulses can be lengthened,
serial command. resulting in uncertainties about exactly when
Up/downsampling of digital audio the value changes between 0 and 1. This
Meridian Comms BNC and DIN results in timing irregularities which can
The MMHR and SmartLink outputs can be
connectors – these enable the processor adversely affect stereo and surround imaging
set to deliver either standard (44.1/48 kHz)
to be integrated with a Meridian audio/ and blur the soundstage. These problems are
or high resolution (88.2/96 kHz) sample rate
video system and controlled by it, for minimised by the buffering stage resulting in
digital audio, with resolution enhancement to
example, switching the HDMI input when the the highest possible audio quality from the
appropriate selection is made via the system original HDMI signal.
When set to standard rates, the output
Non-Meridian sources sending audio via
is either 44.1 or 48 kHz irrespective of
HDMI Inputs H1–6 – These follow the HDMI should in most cases be configured
the input rate, high sample rates being
standard input identification in a Meridian to decode the audio to PCM in the source
downsampled by a factor of two (ie an 88.2
system (this can be overridden when the component to take advantage of the
signal is downsampled to 44.1, while a 96
system is being configured). resolution enhancement and upsampling
kHz signal is downsampled to 48 kHz). 44.1
features of the HD621. As a general rule,
and 48 kHz rates are unchanged.
HDMI Output: Video – This outputs the audio from Meridian sources is fed direct to a
video information present on the selected Meridian surround decoder via SmartLink.
When set to high rates, the output is
HDMI input. By default, it does not carry the
always either 88.2 or 96 kHz, irrespective
audio information, but can be configured to Lip-sync Delay
of the input rate. Standard sample rates
are upsampled by a factor of two using The processor also includes a configurable
Meridian’s powerful DSP technology, so that audio delay of up to 85ms to allow lip-
MMHR Output – This RJ45 connector
input signals of 44.1 and 48 kHz are output syncing in the event of a delay between the
carries eight channels of balanced digital
at 88.2 and 96 kHz respectively. 88.2 and audio and video. This is often the case when
audio data at up to 96 kHz sample rate
96 kHz input signals are passed with their an amount of digital video processing is
conforming to the Meridian Multichannel
sample rates unchanged. being carried out, which can add considerable
High Resolution (MMHR) specification, with
latency to the system (video processing is
encryption where required to carry high-
FIFO Buffering more complex, thus more time-consuming,
resolution audio data.
than audio processing in most cases).
In addition to the features noted above, the
Meridian Audio Limited, Latham Road, Huntingdon, Cambridgeshire PE29 6YE, UK. T +44(0)1480 445678 F +44(0)1480 445686 E firstname.lastname@example.org
Meridian America Inc., 8055 Troon Circle, Suite C, Austell, GA 30168-7849, USA. T +1(404) 344 7111 F +1(404) 346 7111
HD621DS-ENG v1.4 • REƒ • P88379 • 20090114