Meridian America 561 manual Movie formats, How does THX fit in?, Music formats, Bass management

Product Information Meridian 561 January 1999

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.

Registered trademarks: “THX” and “THX Cinema”Lucasfilm Ltd; “Dolby”, “Pro Logic” “DolbyDigital”and “AC-3” Dolby Laboratories Licensing Corporation; “Ambisonic” Nimbus RecordsLtd; “Trifield” Trifield ProductionsLtd; “Meridian”, “Boothroyd Stuart Meridian”, “MLP”, “Meridian Lossless”, “MeridianLossless Packing”, “LipSync”and “Meridian Digital Theatre” Meridian AudioLtd; “DTS” Digital Theatre Systems Inc.; “DVD” DVD Forum.