Cambridge Audio 551R user manual Surroundsoundmodes, DTS-HDHighResolutionAudio, MonoBackSurrounds

Surroundsoundmodes

The 551R supports several music and home-cinema listening modes. The outputthe551Rcanprovide,dependsbothonthesourcesignalpresent,the speaker setup selected and the decode mode selected. Before we describe how to operate the 551R, below is a brief guide to the Surround Sound formatsthatthe551Riscompatiblewithforreference:

Dolby’s lossless audio technology developed primarily for high capacity Blu- ray discs/players. Dolby True HD delivers theoretically bit-for-bit sound identicaltothestudiomasterbytheuseof100%losslessencoding.Previous formats such as Dolby Digital 5.1 or EX have used lossy encoding where some data (that is theoretically less audible) is always lost in the encoding process to reduce the storage capacity needed on the disc. This is a new formatthatsupportsuptoeight(usuallyusedas7.1)full-rangechannelsof 24-bit/96kHzaudioortwochannelsof24/192kHzviaBlu-raydiscsand is not backwards compatible with earlier schemes. The format can either be transmitted as a ‘bitstream’ to the 551R for internal decoding (recommended) or can be decoded by some Blu-ray players internally and sent to the 551R as multi-channel PCM. In both cases an HDMI connection isrequiredtothe551RandasuitableBlu-rayplayerasDolbyTrueHDisonly evertransmittedoverHDMI.

Anencoding scheme based on the original Dolby Digital CODEC, but with enhancements to improve coding efficiency and improved audio quality. Dolby Digital Plus supports 7.1 fully discrete channels compared to Dolby Digitals5.1(or6.1initsEXvariantwherethe6thchannelismatrixencoded). TheseDolbyDigitalPlusbitstreamsarenotbackwardcompatiblewithlegacy DolbyDigitaldecodersbutrequireanAVReceiverdevelopedtodecodethem (suchasthe551R)andanHDMIconnectionasDolbyDigitalPlusiscurrently onlytransmittedoverHDMI.ItishoweverarequirementthatanyDolbyDigital Plus enabled Blu-ray player must also be able transform the Dolby Digital Plus into a backwards compatible Dolby Digital 5.1 output for playback on legacy Dolby Digital systems. The 551R is however fully compatible with DolbyDigitalPlus.

A newlossless audio CODECfrom DTS, rather than being incompatible with earlier versions, DTS-HD Master Audio is transmitted as an extension to a normal DTS bitstream. A second embedded stream is sent which contains the "difference" between the original studio master and the lossy compressed DTS, plus the two extra channels. DTS-HD Master Audio enabled devices (such as the 551R) are able to use this difference information to recreate a bit for bit lossless version of the original 7.1 data. DeviceswhichdonotsupporttheMasterAudioextensionsimplydecodethe original 5.1 DTS stream and ignore the Master Audio extension providing backwardscompatibility.

DTS-HDHighResolutionAudio

KnownalsoasDTS-HRanextensiontotheoriginalDTSaudioformat.DTS-HD High Resolution Audio supports 7.1 fully discrete channels compared to DTS’s 5.1 (or 6.1 in its DTS ES Matrix or DTS ES Discrete variants). As with DTS-HDMasterAudioasecondembeddedstreamissentwhichcontainsthe "difference" between the original studio master and the lossy compressed DTS, plus the two extra channels, however in this case the extra stream is also formed by lossy compression. Effectively this is a 7.1 version of DTS which can be decoded by devices (such as the 551R) which are able to decode DTS-HD High Resolution Audio. Devices which do not support the High Resolution extension simply decode the original 5.1 DTS stream and ignoretheHighResolutionextensionprovidingbackwardscompatibility

KnownalsoasDD(3/2)orDD5.1,provides(upto)5.1outputfromsuitable encodedDolbyDigitalmaterial,with5mainchannels(FrontLeft,FrontRight, Centre,SurroundLeft,SurroundRight)andaLowFrequencyEffectsChannel for the subwoofer, all discretely encoded. Decoding Dolby Digital requires a Dolby Digital encoded DVD disc and a digital connection from the source equipment(SuchasaDVDplayer)tothe551R.

Note:DolbyDigitalandDTSformatscansometimescarrylesschannelsthan their maximum such as Dolby Digital (2/0) which means a Dolby Digital encoded signal which is actually only carrying a two channel stereo signal (otherchannelsinactive).

Knownalso as DTS (3/2) or DTS 5.1, DTS provides (up to) 5.1 output from suitableencodedDTSmaterial,with5mainchannels(FrontLeft,FrontRight, Centre,SurroundLeft,SurroundRight)andaLowFrequencyEffectsChannel for the subwoofer, all discretely encoded. Decoding DTS requires a suitably encodedDTSdiscandadigitalconnectionfromthesourceequipmenttothe 551R.

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KnownalsoasDD(3/3)orDD6.1,anenhancedformofDolbyDigital.Ontop
ofthediscretelyencoded5.1channelsDDEXprovidesanextra6thchannel
(Surround Back, giving 6.1) matrix encoded into the rear surrounds for
greater image depth and more solid sound localisation behind the listener.
DDEXrequiresaDDEXencodeddisc.DDEXisbackwardscompatiblewith
DD5.1decoding.IfDDEXisdecodedasnormalDDtheSurroundBacksignal
will be present in both Left and Right Rear Surrounds (forming a phantom
rear centre). It can also be decoded as 7.1 by sending the Surround Back
decode to both the Surround Back Left and Right speakers (forming two
monoBackSurrounds).

Known also as DTS (3/3) Matrix, an enhanced form of DTS. On top of the discretelyencoded5.1channelsDTSESalsoprovidesanextra6thchannel (Surround Back giving 6.1), matrix encoded into the rear surrounds for greater image depth and more solid sound localisation behind the listener. DTS ES requires a DTS ES encoded disc. DTS ES material is backwards compatible with DTS 5.1 decoding. If DTS ES is decoded as normal DTS the Surround Back signal will be present in both Left and Right Rear Surrounds (forming a phantom rear centre). It can also be decoded as 7.1 by sending the Surround Back decode to the both the Surround Back Left and Right speakers(formingtwomonoBackSurrounds).

AnotherenhancedformofDTS,alsoknownasDTS(3/3)DiscreteorDTSES Discrete6.1.DTSESDiscretealsoprovidesanextrachannel(SurroundBack) for greater image depth and more solid sound localisation behind the listener, however in this case extra data is included in the bitstream so that all channels are discretely encoded. The Surround Back has greater separation from the other channels than is possible with matrix encoded technologies.DTS-ESDiscreterequiresaDTS-ESDiscreteencodeddisc.

DTS ES Discrete is backwards compatible with both DTS 5.1 and DTS ES Matrix 6.1 decoding. If DTS ES Discrete is decoded as normal DTS the Surround Back signal will be present in both Left and Right Rear Surrounds (formingaphantomrearcentre).IfDTSESDiscreteisdecodedwithDTSES Matrix the Surround Back signal will be decoded separately (i.e. as 6.1) but by a matrix process, which will give the same channel separation as if the sourcediscwereactuallyDTSESMatrix(butnotasgoodasDTSEXDiscrete). Itcanalsobedecodedas7.1bysendingtheSurroundBackdecodetoboth the Surround Back Left and Right speakers (forming two mono Back Surrounds).

ThereplacementfortheoriginalProLogic,ProLogicIIisatechnologywhere 5 channels (Front Left, Front Right, Centre, Surround Left, Surround Right) areencodedintoaStereomixbyananaloguematrixprocess.DolbyProLogic II material can be played back by normal Stereo equipment (as Stereo) or decodedinto5channelsurround-sound.

DolbyProLogicIIiscompatiblewiththeearlier4channel(Left,Centre,Right and mono Surround) Dolby Pro Logic system (which was the decoding counterpart to Dolby Surround encoding) as used widely on Video tapes, TV broadcastsandearlierfilms.

Note: Pro Logic does not include a Low Frequency Effects channel for the Subwoofer,butthe551RcancreateaSubwooferoutput(for5.1)viaBass management. Refer to the ‘Tone/Sub/LFE configuration’ section in the ‘Operatinginstructions’partofthismanual.

Anewerversion of Dolby Pro Logic II which is able to recreate 7 discrete surroundsoundchannelsfromsuitableencodedstereosourcematerial. Pro Logic IIx also has modes for post processing either Stereo material or 5.1 material into 7 channels whether or not it has been Pro Logic IIx encoded. When5.1decodingisrequired,DolbyPrologicIIdecodingwillalwaysbeused bythe551RinplaceofProLogicIIxasIIxonlyworksfor7channeloutput.

Note:ProLogicIIxdoesnotincludeaLowFrequencyEffectschannelforthe Subwoofer,butthe551RcancreateaSubwooferoutput(for7.1)viaBass management. Refer to the ‘Tone/Sub/LFE configuration’ section in the ‘Operatinginstructions’partofthismanual.

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