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Product Information Meridian 561 January 1999
Registered trademarks: “THX” and “THX Cinema” Lucasfilm Ltd; “Dolby”, “Pro Logic” “Dolby Digital”and “AC-3” Dolby Laboratories Licensing Corporation;
“Ambisonic” Nimbus Records Ltd; “Trifield” Trifield Productions Ltd; “Meridian”, “Boothroyd Stuart Meridian”, “MLP”, “Meridian Lossless”, “Meridian Lossless
Packing”, “LipSync”and “Meridian Digital Theatre” Meridian Audio Ltd; “DTS” Digital Theatre Systems Inc.; “DVD” DVD Forum.
Movie formats
It was natural that when Meridian
turned their attention to Pro Logic and
THX, the only way they could satisfy
their exacting standards for clarity,
transparency and function was to
develop the whole thing from scratch
using only the best hardware and
software DSP techniques.
Like in the Meridian 565, all the
surround processing is performed in
powerful audio computers, using
algorithms and code developed
uniquely by Meridian. This approach
has allowed our customers to obtain
hardware and/or software upgrades to
keep up with the latest sources.
The Meridian 561 uses three powerful
DSP processors to provide movie
modes for Pro Logic, THX, ‘stereo
surrounds’ and Academy, and
decoding for Dolby Digital (AC-3), DTS,
MLP and MPEG Surround.
The Dolby Digital decoder built by
Meridian is the most powerful on the
market and passes all the most
extreme bitstream tests. Dolby Digital is
the preferred audio format for DVD in
NTSC territories.
Dolby Digital is also available on
NTSC LaserDiscs – to replay these, a
Meridian 519 Demodulator is also
required.
MPEG Surround is the preferred
audio format for DVD in PAL territories;
however, MPEG audio is widely
available – including US satellite
broadcasts and in computer
multimedia.
Finally, in addition to AC-3 and
MPEG, the 561 will decode DTS. The
processor fitted to 561 is fully capable
of decoding all the DTS formats seen
on DVD – as well as DTS from
LaserDiscs and CDs.
How does THX fit in?
THX Cinema has a huge amount to
offer in the 5.1 era. The 561 has all the
signal processing in place to comply
with THX requirements for Dolby
Digital, DTS and MPEG. The front
channels carry re-equalisation; the
surrounds use a new timbre-match
curve and an updated de-correlation
technique.
Music formats
The 561 provides Meridian’s now-
famous music-processing modes
including: Music, Trifield, Ambisonics,
SuperStereo and Music Logic – as well
as 2-channel stereo bypass and Mono.
Bass management
The 5.1 signal has the potential to
require a 12dB increase in bass power
handling in a system. Not only can the
LFE (Low-Frequency Effects – i.e. 0.1)
channel convey 10dB more bass, but
the potential exists for that to happen
as well as full bass level in the other
five channels.
Although the Dolby Digital, MPEG
and DTS encoders limit the total bass
level to around +15dB, the resulting
bass energy can still be incredibly
demanding for even the very best
systems – and equally important – may
be disastrous for other, less capable,
speakers.
The Meridian 561 incorporates a very
sophisticated series of bass protection
schemes for digital surround formats.
The overall amount of LFE added in
can be controlled by the user. In
addition, the 561 has a bass limiting
function to control the total amount of
bass passed to the system.
As well as the overall bass protection,
the 561 can monitor all eight speaker
outputs. If the signal demands more
bass than a speaker can supply, a
proprietary, psycho-acoustically
optimised limiting filter momentarily and
elegantly reduces the load on that
speaker. This unique protection method
means you can get the most out of all
the speakers in the room without any
fear of damage or unpleasant overload
noises.
Inputs and outputs
The 561 offers both analogue and
direct-digital inputs and outputs. Eight
digital and six analogue outputs provide
feeds for any combination of Active,
Passive, Digital or DSP loudspeakers
in 12 different layout configurations
including up to 3 different subwoofer
signals. Each output is individually
adjustable for type, sensitivity and time
alignment.
Specification highlights
Audio inputs
8 analogue adjustable
1 digital optical
5 digital coaxial IEC1937, IEC958
Audio outputs
6 analogue for: main or sides, centre, sub
and rear speakers
8 channels digital output for: main, sides,
centre, sub and rear speakers
2 analogue tape. Independent Copy
Video inputs
4 composite video inputs
4 S-VHS video inputs
Video outputs
Tape outputs for composite and S-VHS
Main outputs for monitor of composite and
S-VHS
On-screen display for user and setup on
both composite and S-VHS
S to composite conversion
Others
Flash memory for easy updates
RS232 for computer control, setup and
software updates
2 Trigger outputs
Music signal processing
Mono, Stereo, Music, Trifield, Super
Stereo, Ambisonic, Music Logic.
Movie and TV processing
Pro Logic, THX Cinema, Academy,
‘Stereo’ Surrounds, TV Logic.
Decoding for: MLP, Dolby Digital AC-3,
DTS and MPEG Surround.
Controls and Display
Front panel controls for: Source, Copy,
Mute, Display, Volume and Off. Other
features accessed using a Meridian
System Remote (supplied).
12-character dot-matrix display; lights for
AC-3, DTS, MPEG and THX.