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OK - Lets get 7.1 straight.

Discussion in 'AV Receivers & Amplifiers' started by Craig_Nike, Dec 12, 2001.

  1. Craig_Nike

    Craig_Nike
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    I know what 5.1 is and where the speakers go.
    I know what DD 5.1 EX is
    I know what THX 5.1 EX is
    I know what dts 5.1 ES is
    I know what dts 6.1 ES is

    In fact I am very excited to say that my receiver does them all.

    Can somebody please explain to me what 7.1 is and where the speakers go ?

    Does 7.1 have a centre rear channel ?
    Is it 2 channels of side effects ?
    What are side effects and are they full range ?
    Is it 1 channel of centre rear and 1 channel of side effects driving 2 speakers ?
    Have any movies in the Cinemas ever been shown with it ?
     
  2. Guest

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    1. Right
    2. Centre
    3. Left
    4. Left Surround
    5. Left Rear
    6. Right Rear
    7. Right Surround

    .1 Sub Woofer
     
  3. russraff

    russraff
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    I think that 7.1 is just refering to the two speakers you normally have as your rear centre channel. So 7.1 is actually 6.1, but gets the extra number due to the two speakers acting as one channel.
    Also, I believe that if you use dipole speakers as your rear centre channel, then these speakers should have their orientation reversed. So the one marked "Right" goes to the "Rear centre left" position, and so on.

    Of course, I could be completely wrong...

    Russell
     
  4. t-force

    t-force
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    There is, at the moment, no such thing as true 7.1. A lot of people use it to describe systems with a pair of speakers for the back channel.

    The closest thing to 7.1 at the moment is DTS ES discrete, which has 7 discrete channels (inc. sub), but no-one as of yet has gone all the way with 8.

    Lexicon do have their Logic 7 processing, which is the traditional 5 speakers, plus two of what they call "side" speakers, but that is a matrixed format.
     
  5. Fuddle

    Fuddle
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    The 7.1 is for a surround rear left and right channel. My amp, a Pioneer VSX859 supports this and shows diagrams to explain.
     
  6. Reiner

    Reiner
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    Like t-force says there is currently no such thing as 7.1 available for the home cinema market.

    SDDS for example is a true 7.1 system (two additional front speakers) and I think MPEG-MC is capable up to 7.1 (like e.g. DTS which is not limited to 5.1 or 6.1 but scalable).

    Some people confuse the naming conventions (probaby just to simplify things), DD Ex and DTS Es are actually 3/2:3.1 systems and only DTS ES Discrete is a true 6.1 system.
    Yet all of those are recommended to use two additional rear speakers (the signal remains mono though) on top of the traditional 5.1 system and hence some people wrongly call it 7.1 (or 6.1 if only one speaker/channel is used).

    And btw, cinemas are 5.1 (DD/DTS 5.1) or 7.1 (SDDS), DTS ES Discrete 6.1 / THX Surround Ex) were specifially created for home cinemas only since most people can't afford myriads of speakers and the required amplification for it like you find it in the cinema.
     
  7. uncle eric

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    I'd just like to throw another spanner into the equation and confuse things further.
    While seven speakers with a pair for the matrixed back or rear channel is acceptable for 6.1 matrix (whether DTS or DD EX), the latest line of thinking for 6.1 discrete is that only one back/rear speaker should be used.

    Eric
     
  8. Craig_Nike

    Craig_Nike
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    Thanks guys - good clarification.

    So all the amps that claim 7.1 just have an additional amplifier in them (7 amplifiers) and just send exactly the same signal to both centre rears ?

    Now - here is my doosy.
    If I have a 6.1 amp, and I can send a centre rear channel through to a speaker - but instead I 'Y split' to 2 speakers back there (or run them in series) what happens to the amplification running through my wire ?

    Does the 100W going to the centre rear turn into 2 x 50 into each of the 2 speakers ? Or does it go 80 W & 20 W ?
    I know ohms come into this here somewhere but I am very afraid of ohms because I understand them less than my wifes mood will be tomorrow.
     
  9. Reiner

    Reiner
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    Well, some amplifiers are "6.1" (e.g. Yamaha DSP-AX1) while others are "7.1" (e.g. Denon AVR-3802).

    Some even do the decoding but do not have the required amplification on board and hence require an additional power amp which will be connected to the pre-outs, see e.g. the Denon AVC-10SE.

    You can connect two speakers (in parallel) to any ouput, but I recommend this only if they are identical and have at least 8 Ohm impedance as not to give too much load to the amp.
    The power output of the amp will remain at e.g. 100 Watt but it's shared between both speakers.

    You could connect just one power amp or two channels using two pre-outs, if there is only one pre-out you can just split the signal (using a Y-adaptor) and drive two speakers with two power amp channels if required.
     
  10. Guest

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    Can someone draw a 7.1 setup please!
     
  11. Jase

    Jase
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    Its like this

    FL....... C.......... FR


    SL ....................SR


    SBL ............. SBR

    Roughly!!;)
     
  12. Reiner

    Reiner
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    FL....... C.......... FR

    ..........SUB............

    SL ...SBL...SBR...SR


    You may substitute the SBL and SBR with a 'Center rear' for a 6.1 setup.
     
  13. Jase

    Jase
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    OOOPS!! forgot the sub!!:eek:
    :rolleyes:
     
  14. Guest

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    I have a 4 * 4 m square room with a bay window.

    See the enclosed .bmp.

    How do I set up 7.1

    I need to make sure that 7.1 will be available on any of the sofas I would sit on.

    :confused:
     

    Attached Files:

  15. sweetmate

    sweetmate
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    The EX/ES sound format was not created for home cinemas, it was created as a cinematic sound format and sound designer Gary Rydstrom was the driving force behind it. He essentially invented the format by requesting an extra channel from Dolby and THX and I've heard that his first test of the format was on the soundtrack to "A Bug's Life" (try it in EX, it works pretty well).

    The format was theatrically marketed as Dolby Digital Surround EX and launched with the Phantom Menace soundtrack (Rydstrom) in May 1999 and closely followed that summer by The Haunting (again mixed by the amazing Mr Rydstrom) and Austin Powers 2 which all featured Dolby Digital Surround EX soundtracks.

    There are commercial decoders built for cinemas for retrieving the EX/ES channel in matrix form from both Dolby and DTS but not for decoding DTS-ES in discrete mode because as far as I understand it, an extra discrete channel cannot be encoded into the cinema version of the DTS codec.
     
  16. Reiner

    Reiner
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    Oink Oink, I think with no room behind the listening position there is not much point with a 7.1 setup, as well it may depend on what speakers (normal or di/bipole) you intend to use.

    Thanks for the clarification, sweetmate, had forgotten that TPM did actually feature DD Ex at the cinema.
     
  17. Guest

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    I have upto a foot behind the sofas.
     

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