Meridian Audio Stereo System 568V25 User Manual

Technical Information  
JMB v 1.0 – 8th Dec 2003  
V4 Presets and Usage  
Introduction.  
This document is intended as an introduction to the style of DSP Presets in 861v4, G68 & 568v2.5 -  
primarily for customers who are already familiar with earlier Meridian processors such as the 561 or earlier  
versions of 568 and 861.  
861v4, 861v3.5, 568v2.5 and G68 share the same decoder modes and DSP presets. This is at the point in  
time where they incorporate THX UltraII Cinema and Dolby PLIIx.  
Basic Preset structure - why have we changed it?  
In older products a Preset was linked directly to a type of audio stream. E.g. “Digital” was a Preset for  
Dolby Digital multichannel streams only, “Dig THX” added THX extensions to the basic Dolby Digital  
mode.  
Adding extra processing modes, such as Dolby PLII and THX Surround EX, was beginning to make the  
range of options quite complicated - particularly in the GUI, where the user is presented with all of the  
possible options at once.  
For these reasons the processing performed in Version4 is split into two parts, the decoder and the mode.  
The mode is what the user sees as a ‘Preset’, the decoder is automatic and does not require any settings  
or adjustment.  
This presents a uniform set of options, based on how many channels of audio are actually on the source  
medium.  
Discrete  
Cinema  
THX  
PLIIx Mov6  
PLIIx Mus6  
THX EX  
THX UltraII  
THX Music  
Dolby Digital 5.1  
DTS 5.1  
MPEG 5.1  
Multichannel PCM  
Multichannel analogue  
Decoder  
Speakers  
Direct  
Music  
Trifield  
Ambisonics  
Super Stereo  
Music Logic  
Mono  
TV Logic  
PLIIx Music  
PLIIx Movie  
PLIIx THX  
Dolby Digital 2.0  
DTS 2.0  
MPEG 2.0  
2-channel PCM  
2-channel analogue  
Decoder  
Speakers  
The decoder mechanism.  
The processors automatically select the decoder based on whatever stream is coming in, be it Dolby  
Digital, DTS, MPEG or PCM. The stream display exists in the same form as previous processors. E.g.  
“DVD AC3 3/2.1 48k”  
In this case the decoder part of the product will pass 6 channels of decoded audio to the surround  
processing section. The user is then presented with a range of Preset options for 6-channel audio.  
Meridian Audio Limited, Stonehill, Stukeley Meadows, Huntingdon, Cambs PE29 6EX  
Tel +44 1480 445678 Fax +44 1480 445686  
 
Technical Information  
JMB v 1.0 – 8th Dec 2003  
What types of streams are associated with which Preset category?  
Streams in parentheses indicate streams that are decoded in a Meridian DVD player.  
Two-channel PCM  
Analogue  
CD  
(MPEG 2/0)  
(DTS 2/0 music)  
(AC3 2/0)  
Music2  
(DTS 2/0 movie)  
Movie2  
Music6  
Multichannel PCM  
Analogue  
DVD-A  
(DTS 5.1 music)  
(AC3 5.1)  
(MPEG 5.1)  
(DTS 5.1 movie)  
Movie6  
Encoded formats  
AC3 2/0  
MPEG 2/0  
DTS 2/0  
AC3 5.1  
MPEG5.1  
DTS 5.1  
Meridian Audio Limited, Stonehill, Stukeley Meadows, Huntingdon, Cambs PE29 6EX  
Tel +44 1480 445678 Fax +44 1480 445686  
 
Technical Information  
JMB v 1.0 – 8th Dec 2003  
What happened to EX/EZ?  
EX and EZ were multichannel Presets that generated an additional mono surround back signal from a  
two-surround signal. These have been replaced by Dolby PLIIx Mov6 and PLIIx Mus6, which generate  
four surround signals from a two-surround signal.  
Can I achieve an equivalent of the old “DTS Music” preset?  
Not directly, but you can set up a ‘phantom source’. If you define a source to have audio input ‘last valid’  
then switching to it will just apply the new default presets to whatever physical source is currently  
selected. A phantom source like this, with the Movie6 Preset set to “Discrete” and the 2+2+2 menu set to  
“7.1” would achieve the equivalent functionality.  
Can I upsample movies?  
Only audio streams that arrive at the processors input as PCM or MHR can be upsampled. The common  
way to achieve this is to use a recent Meridian DVD player to decode the audio stream and output to the  
processor via a multichannel digital connection.  
Can I still force the DTS decoder for sources that play DTS poorly?  
Yes, this feature still exists and is configured in the GUI. The decoder will not play any audio unless it is  
DTS encoded.  
Why aren’t my side speakers playing multichannel audio?  
The “Discrete” preset is designed for use with DVD-A multichannel audio streams. There is a parameter in  
the Preset called “2+2+2” which tells the processor what to do with the centre/LFE channel pair. This  
menu defaults to “5.1”, which means the processor passes the six channels straight through to the  
speakers (performing time alignment and bass management on the way). The menu should be set to “7.1”  
if you want the side speakers to play audio derived from the surround channels.  
Why can’t I add gain to the LFE channel?  
THX require that the default gain applied to the LFE channel during their processing is 10dB, but that the  
user should see this as +0dB. As such the displayed setting of +0dB is actually applying gain of +10dB.  
Discrete is a Music Preset, not subject to THX approval, so the display in this case is allowed to show the  
true maximum value, +10dB.  
What is Automatic THX-EX switching?  
For systems with four surrounds a new setting has been added to THX, THX Music and THX UltraII  
Cinema - automatic THX Surround EX switching. If an EX encoded stream is detected in any of these  
three modes the processor will automatically use THX Surround EX processing to generate the surround  
signals. This will not change the ‘Preset’ chosen, but will change the DSP processing selected. The front  
panel ‘Preset’ display will change to show:  
“DVD THX Sur.EX 65”.  
The user can defeat this automatic switching by setting the “Auto EX?” menu to “no”, in the GUI or from  
the front panel. User Presets can be created (based on THX, THX Music or THX UltraII Cinema) with or  
without automatic EX switching.  
Note that the EX flag is not transmitted via Smart Link, so this feature is not accessible when decoding in  
a Meridian DVD player. Play the Dolby Digital bitstream from the Aux output into a two-channel digital  
input to utilize this feature.  
Meridian Audio Limited, Stonehill, Stukeley Meadows, Huntingdon, Cambs PE29 6EX  
Tel +44 1480 445678 Fax +44 1480 445686  
 

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