Meridian 861Digital Surround controller reference standard

No remote, no box, no power cords and no meridian cables, VERSION 2.81

Meridian Reference Digital Surround Controller 861

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The 861 Reference Digital Surround Controller
Digital signal processing, or DSP, is a technique pioneered by Meridian in hi-fi products for achieving extremely accurate reproduction of audio signals. Unlike conventional analogue systems – which process signals using electronic circuits based on resistors, capacitors, and inductors – DSP works by performing exact mathematical calculations on digital versions of the signals.

The advantage of DSP over analogue circuitry is that the signals are held as precise numbers, rather than voltages in a circuit. This means that any number of stages of processing can be performed with high precision, and without any of the cumulative noise or degradation that inevitably occurs, even with high-quality analogue circuitry. In addition, several of the surround-sound decoding techniques and signal improvement techniques available in the 861 would be virtually impossible to implement in analogue circuitry.

At Meridian we have taken advantage of the availability of high speed DSP microprocessors to incorporate DSP in hi-fi products, and the 861 is the result of over a decade of our research and development in this field.

The 861 takes advantage of DSP for several different functions:
• To de-jitter incoming digital signals and expand the precision of the signal.
• To perform filtering or adjustment of the frequency response; eg treble or bass.
• To decode digitally-encoded signals from Dolby Digital (AC-3), DTS, or MPEG Audio.
• To process the audio into a multi-channel signal, and match the source channels to the configuration of main loudspeakers and subwoofers in the system.
The 861 converts analogue input signals to digital format, using high quality analogue-to-digital converters (ADCs). Digital signals, from CD, DVD, LaserDisc or digital broadcasting, are already in digital format and do not need to be converted.
The signals are then retained in digital form throughout the 861 until they are converted back to analogue form at the analogue outputs, to drive power amplifiers. If you are using the 861 with Meridian DSP Loudspeakers, the signals remain in digital form until the last possible stage.

Format decoding, DSP presets, and layouts
The 861 provides an extensive range of options for decoding and processing analogue and digital signals for multi-channel reproduction.

The formats processed by the 861 can be divided into the following categories:
• Discrete multi-channel.
• Encoded multi-channel.
• Encoded two-channel.
• Conventional stereo.

Encoded multi-channel formats
Dolby Digital
Dolby Digital, previously called AC-3, is the preferred sound format for DVD, and is widely used on NTSC LaserDisc soundtracks. It is also the audio standard for US digital television.

DTS
DTS uses an audio compression technique to encode five channels of audio onto a digital signal. The DTS format is used to encode multi-channel film soundtracks on LaserDiscs and DVD-Video discs. DTS can also be used to compress 5.1 channels of high-quality audio into the same space as two channels of unencoded sound, to provide 5-channel music CDs.

MPEG
MPEG Surround is an alternative to Dolby Digital, used to encode multichannel soundtracks on DVD-Video.
When the 861 detects the input format it automatically decodes it for the appropriate number of speakers. It then allows you to apply a range of signal processing options, called DSP presets. These provide effects such as:
• Creating additional channels to enhance the surround effect.
• Controlling the width and depth of the image.
• Adjusting the tonal balance of the sound.
The presets available for each audio format are described in the following section Two-channel presets

Direct
Uses only the left and right speakers, bypassing spatial processing. Tone controls and speaker protection still operate.

Music
Extracts the mono and surround components of the original recording. The mono element is equalised to match the tone colour of the centre speaker.

Trifield
Similar to Music, but gives a more focused front stereo image and allows the width of the image to be adjusted.

Ambisonics
Decodes stereo-UHJ Ambisonics recordings to produce a realistic soundfield at the listening position.

Super
A variation of Ambisonics that has been optimised to work with unencoded stereo material. Particularly effective on recordings that have been made using true coincident microphones.

Stereo
Applies bass management to the left and right speakers. No spatial processing is performed.

MusicLogic
A music DSP preset based on the ProLogic II processing mode with the addition of user-adjustable steering, designed to provide an exciting experience with many types of studio-produced music.

Mono
Enables listening to only one of two input channels, such as when different languages or material are carried on each channel, or a combined version of the two channels when a mono recording is conveyed on a two-channel carrier.

TV Logic
A movie preset based on the ProLogic II processing mode with the addition of user-adjustable steering, designed to give higher intelligibility and a more appropriate spatial presentation for studio-based TV material.

PLII Music
Designed to use the Pro Logic II processing mode to decode music sources.
It provides additional Width, Dimension, and Panorama preset parameters to allow you to adjust the soundfield.

PLII Movie
Uses the Dolby Pro Logic II processing mode, and is the recommended choice for Dolby Surround encoded material.

PLII THX
Provides additional signal processing refinements developed by Lucasfilm Ltd. designed to provide a better match between the sound of the movie theatre and a home cinema.

Multi-channel presets

Discrete
A multi-channel preset to be used when no further processing is required. Uses the Music speaker layout.

Cinema
Similar to Direct, but uses the 5.1 Movie speaker layout.

EX
Allows 5.1-channel film soundtracks to be encoded with an extra surround channel to give improved surround imaging with four surround speakers.

EZ
A Meridian variation of EX processing with the addition of user-adjustable
steering.

THX
Provides additional signal processing refinements developed by Lucasfilm Ltd. designed to provide a better match between the sound of the movie theatre and a home cinema.

THX EX
A combination of THX filtering and EX spatial processing.

THX Ultra2
Uses a THX proprietary process to create four surround channels from a
5.1-channel film soundtrack.
THX Music
Uses a similar processing technique to THX Ultra2, but optimised for music reproduction.

Ambisonics
Decodes multi-channel B format Ambisonics recordings to produce a realistic soundfield at the listening position. Ambisonics is only available on multi-channel PCM input, such as from DVD-A.

Layouts
The 861 allows you to define three different speaker layouts, called Music, Logic, and 5.1 Movie, optimised for different types of preset. The layout used for each preset is shown in the following table:

Layout DSP presets
Music
Direct, Music, Trifield, Ambisonics, SuperStereo, Stereo, PLII Music, Discrete, THX Music
Logic MusicLogic, Mono, TV Logic, PLII Movie, PLII THX
5.1 Movie Cinema, EZ, EX, THX, THX EX, THX Ultra I

Overview
The architecture of the 861 allows for wide flexibility – future sources and
formats can be handled by upgrading either software or cards.

Meridian MHR Smartlink
The 861 Reference Digital Surround Controller incorporates a unique multichannel link, which allows it to receive an upsampled 6-channel PCM stream from a compatible source, such as the Meridian 800 Reference DVD / CD Player, for the highest possible sound quality.

An additional feature of the Meridian MHR Smartlink is that it obtains intelligent stream content information from the source, allowing the 861 Reference Digital Surround Controller to select an appropriate preset depending on whether the source is music or a movie soundtrack, and whether it is 2-channel or multi-channel.

Inputs
The 861 is a full-system controller preamp that provides seamless control of up to 12 sources.

The optional Tape card provides additional A/D and D/A converters to give support for both tape recorders, extensive 2- and 3-zone multi-room capability (analogue or digital formats), and headphones.

By providing digital as well as analogue inputs the 861 can give radically higher sound quality for sources that are originally digital – like CD, LaserDisc, Digital Radio and DVD.

As well as accepting 2-channel digital audio, the 861 will handle SPDIFencoded Dolby Digital, DTS or MPEG from sources like DVD, Satellite and LaserDisc (via an RF00 LaserDisc Demodulator Card).

Processing
The Meridian 861 routes all signals – if necessary via a 24-bit A/D converter – into the digital domain for processing in the highly developed Meridian 24-bit DSP cards.

The incoming signals are processed using a variety of proprietary algorithms, and up to eight output signals are generated. These output signals can be used to feed a number of speaker layouts, ranging from two to seven speakers with up to eight Meridian digital subwoofers.

The on-board algorithms include Meridian’s own highly transparent Dolby Pro Logic, PLII, Dolby Digital, MPEG Surround, DTS, THX extensions, TV Logic, and a variety of award-winning music programs including Trifield and Ambisonic.

Outputs
The 8+ outputs can be provided as digital signals to feed Meridian DSP Loudspeakers, or as variable analogue outputs using a proprietary on-board 24-bit resolution conversion method.

Video control and OSD
The Meridian 861 provides broadcast-grade video switching options for monitors, projectors and video tape routing. The comprehensive set-up and customising facilities allow the user to link any video and audio combinations to the 12 sources (accessed from the Source key on the front panel or the remote control).

In addition to providing high-quality video buffering, the 861 has the ability to give help and system control feedback information in an on-screen display. Video formats supported include Composite, S, and Component.

Typical specification

Audio in and out
• Up to 12 analogue inputs. User-adjustable sensitivity. Re-nameable legends.
• Up to 12 digital inputs. Re-nameable legends. 32 to 96kHz sampling, and up to 24-bit precision.
• Digital and analogue tape loops.
• Independent copy and 2-room+ capability.
• Up to 10 digital outputs.
• Up to 10 analogue outputs.
• Optional 5.1-channel analogue input.

Control signals
• 3 trigger outputs, programmable by source.
• Meridian Comms and RS232 for control and setup.

Controls, etc.
Front-panel facia controls for: • Source, DSP, Mute, Volume, and Off.
Hinged control panel provides additional switches for:
• Display, Copy, Store, parameter menus, Assign, Calibrate, and Configure. Display
• 20-character dot-matrix display: adjustable brightness and contrast.
• Lights for Dolby, Digital, THX, DTS, and MPE