Can you fake a 7.1 setup by taking a 6.1 receiver and splitting the back channel?

Discussion in 'Speakers & Subwoofers' started by Lanny_B, Apr 11, 2004.

  1. Lanny_B

    Lanny_B Second Unit

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    I have a 6.1 receiver (Onkyo SR600), and I'm wanting to wire for a 7.1 system. I'm wondering if I can take the 6th channel, and somehow split the sign and send it to the two rear speakers.

    My receiver says it has a 6 ohm minimum, and my rear speakers both say 8 ohms on them. So, does that mean I can't do it, because it would be splitting the 8 ohm signal into 4 ohms and 4 ohms? I'm just guessing here.
     
  2. Stephen Hopkins

    Stephen Hopkins HW Reviewer
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    Since there are NO 7.1 sound formats, that's EXACTLY what 7.1 is. There are many 6.1 receivers that have speaker terminals for 2 surround-back speakers. There are a few matrixing technologies out there that give stereo back surrounds (Logic 7, PLIIx, THX-Ultra2) but these are still derived from a single discrete back channel or (most times) from no discrete back-channel at all.

    Essentially what 6.1 receivers w/ 2 back speaker terminals are doing is wiring the 2 in series inside the receiver. If you wire 2 speakers in series to a single surround-back channel you'll be fine. This means + on the receiver to + on speaker 1, - on speaker 1 to + on speaker 2, - on speaker 2 to - on receiver. This gives you a total 16ohm impedance which is just fine for your receiver. If you wired in parallel you would have a total 4ohm load and it could cause problems depending on how well your receiver handles lower impedances.

    Hope this helps [​IMG]
     
  3. Chris PC

    Chris PC Producer

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    Some say two rear speakers is better than a single rear centre due to the fact that a single centre speaker is strange sounding sometimes. Feels like the sound is directly in front of you just quieter. Two rear centre speakers often make it more obvious that the sound is from the rear. ymmv...its just what I've heard.
     
  4. Phil Iturralde

    Phil Iturralde Screenwriter

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    Actually, what Stephen means wire them "in-series", so two 8 ohm speakers will total out = 16 ohms. If you wire them in parallel, the two 8 ohms speakers will = 4 ohms.

    Example: Two 4 ohm speakers wired In-series = 8 ohms ...
    [​IMG]

    Phil
     
  5. DonnyD

    DonnyD Screenwriter

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    I'm using two 8 ohm speakers in parallel for my rear center and love the extra dimension it gives....if you run them in the "small" setting, the 4 ohm load shouldn't cause any problems......and if you're counting, I have a 9.1 setup.....but of course nothing has more than 6.1 anyway but those extra speakers DO make a difference, at least to me........
     
  6. John Garcia

    John Garcia Executive Producer

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    Using the pre-out for the rear center with an external amp and a splitter will solve the problem without having to worry about the speaker impedance.
     
  7. Lanny_B

    Lanny_B Second Unit

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    Well, I wired them In-series like in the picture above. I can hear sound coming out of both speakers, and, I haven't tested them for volume and power yet but, they seem to be fine. Could there be anything wrong with this setup? Because if not, this was a great easy fix.

    Is anything at risk by me doing this? Or am I losing power to each speaker or to other speakers or anything?
     
  8. Allen Marshall

    Allen Marshall Supporting Actor

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    Let me get this straight, if you put on Dolby Digital EX or DTS ES, and you have a 7.1 setup, both rear centers will be working?
     
  9. ChrisWiggles

    ChrisWiggles Producer

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    Yes, this is the preferred setup. A discrete 6.1 (DTS-ES discrete), or matrix 6.1 (DTS-ES matrix, or DD EX) via 7.1 speakers, with the 6th channel split in mono between the rear backs.

    Further processing to create those two rear back in stereo to allow panning around all 4 surrounds can be beneficial too, but not necessary for a "7.1" speaker setup. The latter would not be true 7.1 discrete either, but it would be 7 channels on 7 speakers, rather than 6 channels via 7 speakers.
     
  10. Justin Ward

    Justin Ward Supporting Actor

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    If you find it hard on your amp and you have pre-outs on the reciever, you could get another amp to do the work as well.
     
  11. Lanny_B

    Lanny_B Second Unit

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    I'm wondering how I would know if it's being hard on my amp (I assume you mean receiver, right?)?
     
  12. PeterK

    PeterK Supporting Actor

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    I know I am reviving an old thread here but I would also like an answer to lanny's question of how do I know if I am working my amp (in my case my reciever) too hard with my speakers?
    thanks.
     
  13. Lee Carbray

    Lee Carbray Second Unit

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    If your amp is working too hard it will probabaly get pretty hot. Now receivers generally get pretty warm under normal circumstances, generally if it is too hot to keep your hand on it, it's working to hard. Most receivers now have thermal protection circuits as well that should shut it down before you even realise you are doing damage.
     

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