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Rear speaker position question

Discussion in 'Home Cinema Speakers' started by Stuart Wright, Mar 2, 2002.

  1. Stuart Wright

    Stuart Wright
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    See attached diagram.
    Because of the constraints of the room, the speakers are ceiling mounted. They are direct firing Ruark Dialogue IIs. I'm about to install the EX rears and they will have to go either side of the projector. Because some electricity pipes make the back right-hand corner of the room void, and because the seats are positioned over to the left of center, I'm wondering whether to position the left rear speaker right next to the projector or in the corner or maybe between these 2 positions.
    I can't try various positions to see what it sounds like cos the speakers are 9kg each and the girlfriend won't stand there holding them up for me.
    Where do you think I should place the rear left?
     

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  2. MartinB

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    I'd go for placing it close to the projector, that way everything's nice and symmetrical.

    Martin.
     
  3. Stuart Wright

    Stuart Wright
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    I think I will put there - though it's not symmectrical at the seating positions - which I guess is what counts. Which is what prompted the question.
     
  4. bob007

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    If they are surround back speakers ( by the looks of them they are) they should be placed at a narrower distance than the fronts (L/R)........so i would place it near the projector.
     
  5. Stuart Wright

    Stuart Wright
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    For future reference, Eric was kind enough to send this reply by email:

    Stuart,
    You need to get your two rears as close as you can to each other. As you
    can't get them next to each other, just either side of the Barco will have
    to do. You probably know that a single rear (middle of the back wall) is now
    the order of the day but in your case that solution looks like it would be
    lopp sided as its either just to the left or right of middle rear because
    the Barco looks to be in the way.

    However, mounting the rears in the rear corners (apart from more acoustic
    problems) will result in a poor, irrational and incorrect rear phantom
    image.
    In other words, if the rears are placed in the rear corners, the sound from
    EX/ES matrixed and ES Discrete encoded material (depending on where the
    individual is sitting) will appear to be coming from the left back or right
    back and confusing the image. This is not what the sound designers wanted
    which was to keep this image exactly in the centre back position and extend
    the sound to the side left or side right for further creativity. Placing the
    rears in the far left and right would be further adding to problems with a
    sonic 'hole'.

    THX Ultra 2 have woken to this fact and are now stipulating placement of the
    two rears right next to each other in the centre back position.
    Of course they can't tell the public that they paid for extra amplification
    in their amps for nothing or unnecessarily bought a seventh speaker.
    At least they are correcting their mistake by getting people to place them
    as if the pair were one speaker. Funny how no ones gone balastic over this
    yet but theres still time.
    Your side speakers are dead on.
    Hope the explanation helps.

    Best Regards
    Eric
     
  6. bob007

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    I would have expected more posts than this, as it is a current topic on a few different threads.
    So i suppose those with 6channels (single surround back) are out celebrating and for those with 7 channels (pair of surround backs) are repositioning their speakers right now.

    Feel sorry for those who have spent 15k/20k on dedecated rooms, all nicley furnished and decorated with the wires all sunk in the walls, only to be told their surround backs are in the wrong position, i would be well pi**ed off.

    Only the missus so far........
    My wife thanks uncle eric for bringing this to spectre's attention, and spectre for posting it for our reference, she said this while filling 8 holes in the front room where two speakers were :D.

    We had just decorated 2weeks before xmas.....who said HC isn't fun.
     
  7. johnson

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    I was under the impression(form Dolby/THX)That two rear channels were needed to widen the rear sound.

    Apparently this is needed because a single speaker directly behind the head has been shown to fool the brain into thinking the sound is coming from the front.

    Therefore even having the two rear speakers next to each other,you are still widening the sound feild compared to your single front.

    Once again these are not my Ideas but ones gleaned from the afformention from the avs forums.

    Regards
     
  8. uncle eric

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    Simon,
    The AVS Forum is a good forum. No, let me re-phrase that, its a great forum. There are a number of industry pro's and some fantastic amateurs that contribute with some very helpfull info on the boards.

    However, like many forums, (in the words of Ian J) some members who were newbies two weeks prior, have become experts after a handfull of posts. Or have gone from zero to hero at a speed that would embarrass Isaac Newton.

    Having read rear speaker placement on the Dolby site, these same folks now swear by god that two rear speakers is gospel. If you have a look for yourself, you will see that Dolby also recommend a 'minumum distance of four feet' between these rears.

    THX, in their new Ultra 2 spec, recommend the two speakers to be placed side by side (as in next to each other).

    Who is correct, THX or Dolby?

    Before you answer, THX also recommends the use of perforated screens in Home Cinema's. Many Pro's and knowledgable amateurs wouldn't be caught dead with these screens.

    Look again at the Dolby site (E.S. section), and you will see a speaker placement diagram of a home theater set up illustrating amongst other things the completely incorrect postions of even the front three speakers in relation to the main listening position. The front left and right should be brought forward with 'toe in' applied so that together with the centre, they will be equidistant to the main listening position.

    Sure, you can compensate by using delay but adding more processing, especially when not needed, compromises sound quality further.

    Going back to the subject in hand, I do not agree that by using one rear speaker, sound can 'sometimes appear to be coming from the front'. This is total rubbish IMO.
    The next time someone behind me calls to me, I'll answer looking directly in front.

    Regarding a pair of rears widening the rear soundfield, this again is not true. If the rear were two discrete channels, then yes, sound designers can and would use these to 'widen the soundfield'

    I'm about to make a shocking statement for 'Two Rears' followers. By using two rears you would actually be 'Narrowing' your rear soundfield.

    How? Let me explain. The further apart your 'rear pair' are placed, the nearer to your sides these would be. As the sides are obviously discrete, these can be manipulated by the sound designers to create a soundstage (similar to stereo) between the left SIDE speaker and rear, and right SIDE speaker and rear. The wider the distance between the proposed two rears, the narrower the soundstage would be to the true discrete sides.

    Due to the above FACTS, I suggest that the 'Widening of the rear soundfield' comments made by these 'experts' (in their slang) is total garbage.

    Just a word regarding Cinema's before someone else jumps up and tells me that 'they have multiple rears'.
    Thats right, they do. The reason for this is mainly to envolope the audience without any concern for other matters such as optimal imaging.

    For a 'Perfect' home theater, or as close to perfect as I've seen, look no further than Gary Rebers Holosonic Widescreen Review Lab.
    Each of the SIX speakers is equidistantly placed and toe'd in so as any two vector points image optimally. Perfect.

    As I've mentioned before, I've not heard a single decent logical reason for the use of two rear speakers, where as in point of 'fact', there are many reasons against.

    Eric
     
  9. johnson

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    Eric,
    Thanks for the reply.
    You may be completely correct in everything you say.I don't know.
    I'ts confusing these days.Too many "experts".
    Particularly when big names like,Dolby,THX and DTS disagree.
    I should imagine it will always be this way from now on.I suppose the only "correct" way is the one that sounds good to you.Afterall we all use different equipment.
    I'm using the best equipment I can afford,and I hope I've got it at least partially correctly set-up,but in reality wer'e using different sound formats like those above(and more, TMA7) so one speaker setup can't be perfect for all.
    Anyway,I'm confused
    Best regards
    Simon
     
  10. uncle eric

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    Simon,
    Your Welcome.
    Thank god I'm not an expert.

    Best Regards
    Eric
     
  11. lmccauley

    lmccauley
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    Actually, it happens all the time to me at work - when a phone goes off in one of the desks far ahead or behind me I have to turn my head through about 45 degrees to be sure which direction it is actually coming from.

    I think you need to find a different analogy ;).

    Cheers,
    Liam
     
  12. rigman

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    Uncle Eric

    what about if you have a Lexicon in logic 7 mode. Do your rear speakers still need to be as close as possible to each other or does this just apply to DD EX / DTS ES.

    thanks

    Darren
     
  13. Reiner

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    Interesting thread. Actually I always wondered if somebody has tried to simulate a cinema at home, i.e. uses a speaker array (direct radiating) at the back, driven by multiple (daisy-chained) power amps?

    As for L7 I think it uses two add. side speakers, so I would say the rear speakers should remain where they are.
    (The others are discussing the position of the surround back speakers which are used in Ex/Es systems only.)
     
  14. rigman

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    ooo thats a relief I was just about to get the drill and screwdriver back out ;)

    Darren
     
  15. uncle eric

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    Liam,
    When you say "Far ahead of me", how big is your office and how many phones are there?
    I think you will find that in a typical office, phones are scattered a little more liberaly than your 5/6/7 speakers at home. In large offices containing a multitude of phones all producing the same ringing tone, confusion sometimes does arise.
    However, we are talking about a few speakers with a 'slightly' wider frequency range than the average ring tone, thus making source location a little easier.
    Any other analogy you can think of?

    Eric
     
  16. uncle eric

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    Guys,
    Reiner is correct. We are discussing the 'SINGLE' rear channel in an EX/ES set up.
    Logic 7 is another long story that would justifiy another thread in itself.

    Eric
     
  17. Jase

    Jase
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    Angling the rear centre speak down towards the listening position helps greatly, did in my case, mind you I´ve now got two rear centres close together angled down.

    In my case the two rear centres spread out did cause problems with sound coming in front of me, also buggered up the side surrounds as well, which was weird.
     
  18. Lowrider

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    If you are not sure, why not stick to 5.1 with the surround speakers in the back corners... :confused:

    It works great, looks good, and doesn´t bother the wife too much, not to mention the economy in speakers and amps... ;)
     
  19. lmccauley

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    I have difficulty identifying 2 phones about 20' in front and 2 also about the same distance behind me on the first ring. I then turn my head a bit and I can identify them on the second ring.

    I was just doing a bit of stirring, to be quite honest ;). I have never heard a well set-up 7.1 system in either configuration, so I'm really just listening in to the thread, rather than offering an opinion.

    This, and especially the REL SUBterfuge threads have been fascinating.

    Cheers,
    Liam
     
  20. uncle eric

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    Liam,
    I'm going to send Chompy round :eek: .
    To be honest with you, I have trouble with my wifes location when she's calling for me. :mad: :rolleyes:

    Best Regards
    Eric
     
  21. uncle eric

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    Reiner,
    I wouldn't want to simulate any Cinema I've been to in the last 2/3 years. I think that a well set up dedicated room will equal and and in some case's, better the 'Cinema Experience' offered in most theatres.

    Eric
     
  22. Phil Hinton

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    I have just upgraded to the ex/es club, mainly out of interest to see how different it sounds. I was quite happy with 5.1 to be honest, but when the opertunity arouse I thought what the hell and swapped my Yammy A2 for a Denon 3801.

    I have positioned the rear channels side by side and central to my seating position. I have found this approach to give the best results, and now want to experiment with dipoles insteda of Direct radiators. This set up means i clearly get the right signals coming from the right directions and The Haunting in dts discrete sounds fantastic.

    But as I understand it for Logic 7 the rears should be spaced out a little and toed in, I would hate to try and come up with a comprimise for THIS!
     
  23. Lowrider

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    Phil,

    I saw your setup in another post, and wanted to ask if you tried the surrounds in the back corners, with and without back speakers, that´s how I would have set them...
     
  24. uncle eric

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    Antonio,
    Are your L/R side's in the back corners?

    Eric
     
  25. Phil Hinton

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    Antonio,

    The Pictures you saw were before I repositioned the Rears to the side walls, slightly above seating position and facing the seating position. The Back Rears are directly behind me at the same height.

    Cheers
     
  26. Lowrider

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    My surrounds are in the back corners, I hated them besides the seating position, as I ended up hearing them too much, very distracting. Besides, it is supposed to be the best position for music...

    I didn´t get in the 6.1 bandwagom, I don´t see a big advantage, and it would ruin the decoration... ;)
     
  27. uncle eric

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    Antonio,
    I have my reservations regarding placement of (any) speakers in corners but if you are happy with this arrangement, both visually and sonically, thats all that counts .

    Eric
     
  28. Lowrider

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    I also wouldn´t place my front speakers in corners, unless they where made for that position...

    In this case, when I say corners, I mean the general place, in fact my lounge has open sides in the back... Anyway I also think it wouldn´t be critical if they where in corners, you just have to put them where the sound is satisfactory, could be one foot away or so, and the toeing in depends of how far you seat too...
     
  29. uncle eric

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    ?????????

    Eric
     
  30. Lowrider

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    Yes, there where speakers made for corner placing, for instance the Altec Lansing horns...

    Also some Boston made to be placed against the back wal (I owned a pair), they where wide, tall, but very shallow...
     

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