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Height of rear speakers (Quads) in 5.1 setup

Discussion in 'Home Cinema Speakers' started by krungthep56, Apr 10, 2005.

  1. krungthep56

    krungthep56
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    Hi,

    I have a pair of Quad 12L's for fronts and have just added a pair of 11L's for rear service.

    I have read earlier threads on rear speaker positioning, and understand that the rear pair should be between 90-120 degrees from the viewing plane. However I can't come to a conclusion on the best placement for the rear pair.

    Am I correct in thinking that (i) they should be higher than the fronts and pointed down towards the seating?? - in which case they would need to go on wall brackets?? Or (ii) do they go on stands similar to the fronts with the tweeters at ear height and pointed towards the listener?? Or (iii) does either option work equally well.

    Bearing in mind the need to select based upon the room characteristics, option (i) is preferred in my sitation, but I have read differing opinions on the placement of speakers on brackets presumably due to the so-so quality of wall brackets, and speaker placement immediately adjacent to the wall?

    Regards,

    HT
     
  2. nheather

    nheather
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    Although inexperienced (so others will be better qualified to answer) I will give the views I have gained from asking similar questions.

    The aim is that the rears provide background sound and it should not be possible to pinpoint the direction of the sound coming from them.

    I've been told that the rears should be at hear height (or slightly above) and in line with the listener. This is fine with dipoles/tripoles but if you are using normal satellites then this position can result in the rears being too close to the listener and giving directional sound. So if using normal satellites, the best approach is to mount them higher up the wall.

    I hand over to the experts to give a more technical response.

    Cheers,

    Nigel
     
  3. krungthep56

    krungthep56
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    Hi Nigel,

    Cheers for the succinct advice - experts awaited, hello hello.

    HT
     
  4. Jules Tohpipi

    Jules Tohpipi
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    A quick question. If you are putting the speakers on the rear wall, then how far from the rear wall are you typically sat ?
     
  5. krungthep56

    krungthep56
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    Hi,

    The main listening position (sofa) sits immediately in front of the back wall where the speakers would be either mounted or sit on stands: the max comfortable distance that I can push this forward would be say 50cm, although ideally they would be closer to the wall.

    I guess anything will be a compromise, but suggestions welcome.

    Regards,

    HT
     
  6. Jules Tohpipi

    Jules Tohpipi
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    In which case you are best proceeding with option i)

    Generally speaking, rear speakers need to do two jobs simultaneously:-

    a) Act somewhat like front speakers by providing direct sound to the listener. This will allow you to localise 'stereo' rear effects (in the same way that properly positioning front speakers allows you to hear stereo effects). If you are not hearing direct sound from the rear speakers - but only reflected sound - then stereo info in the rear channels will be lost. So, you need to set up your rear channels such that you can hear some direct sound from them.

    b) Provide plenty of ambience. Ambience is sound that has reflected off something before it reaches your ears. Ambience differs from simple 'reflected sound' in being a whole host of reflections. To provide good ambience, then the rear speakers need to generate plenty of reflected sound in the room, and that typically means putting them in a high position (such that sofas, people etc don't absorb the sound waves hence stopping reflections). It also means not angling them down...

    The ideal scenario is to be ahead of the rear wall, such that you can put the rear speakers up high, not angle them down, meaning that you can hear some direct sound from the rear speakers (they're not firing over your head) whilst getting plenty of ambience (!). I don't think you are not going to be able to hit both marks here because you are so close to the back wall, so you need to choose between having rear effects (option i) or just ambience (put them up high and don't angle them - sound fires over your head). Personally, I would go with the having rear effects option - but you (and others) may disagree; give both a try. In any scenario option ii) is incorrect IMO.

    HTH
     
  7. krungthep56

    krungthep56
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    Hi HTH,

    Thanks for the considered response, and I will follow your lead by trying out the solution of brackets on said rear wall, higher than the listening position so that they can hopefully give both some direct and reflected sound. Sounds like a tall order for a 'traditional' speaker, to satisfy both criteria but will have a go.

    I have the speakers and cable already purchased and will head out this weekend to get the cable terminated, then will experiment with various shelves and stands as a temporary solution before fixing into wall. One concern I had was in putting the Quads so close to the rear wall, but will experiment and have a go to see what happens.

    Will update after installation, and any other suggestions.

    Cheers for the info, and BFN

    HT
     
  8. rishi

    rishi
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  9. Jules Tohpipi

    Jules Tohpipi
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    In a rear speaker application, I would not be too concerned about the Quads being very close to a rear wall. Yes, bass will be slightly boosted, but you don't need to worry about bass rhythms and drums etc being ruined - as you would with doing the same with the front speakers. A very mild bass boost on explosions, helicopters, etc is nothing to worry about, and typically the film score is not mixed with much bass on the rear channnels, so you should be completely in the clear putting these smallish bookshelf speakers on the rear wall.
     
  10. krungthep56

    krungthep56
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    Thanks guys,

    After having spent countless hours poring magazines and investing in and reading 'the best guidebook we've read on the subject' (ie home theatre), I've learned more from your posts in a few days! Can't wait for the weekend.

    Regards,

    HT
     
  11. OldSkoO1

    OldSkoO1
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    Hi there,

    I was in the same position as you about a month ago. I was pretty in-experienced when it came to all this but i enjoy reading up on stuff and learning how to get the most out of things. So from my very basic prespective i posted this in the all in one forum. Its basically my interpritation of what i've learnt since i got my system.

    Overall, moving the speakers off stands and onto wall brackets in a smallish living room made the world of difference. The rear soundstage opening up loads by placing them high on the walls and pointing them towards the front of the seating position and i did angle them slightly down. But on advice in this thread i might try leveling them out :confused: :) Having them on stands at ear height (as mentioned earlier in this thread) didnt sound too great due to things absorbing the sound. Based on this i'd definatly wall mount them but the hight and direction will ultimatly be up to you. :)

    GL!
     
  12. krungthep56

    krungthep56
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    Hi OldSko01,

    As an aside, and out of interest, where did you find wall brackets and were they of decent quality?

    Regards

    HT
     
  13. OldSkoO1

    OldSkoO1
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    I got some AVF wall brackets, these ones : http://www.avf.co.uk/product.php?cat=HF&product=P6199

    They are very decent brackets and apparently recommended by denon for my particular speakers. I did have major trouble installing them and its a must for them to go into brick or the wood joins on your plaster walls. The denons connect underneath and they only just hold up.
     
  14. demonhale

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    As an enthusiast and as I was taught in school (engineering acoustics) it is very hard to look for help online for 5.1 and quad sound setup. Thus I have formulated quite a short method for Speaker Placement. This is measured so do the Math. Anyway, If youve got the speakers, all you need is a tape measure. I will be talking in inches and will have an approximate measurement error of +-5%. Now I am currently working on an in-depth guide to speaker placement, ideas on room acoustics etc. and post it on my webpage. All of these doesnt require a professional fee, I believe in freedom. All I need are feedback so that I could continue on learning from others. Here Goes.

    Measure the distance between your Left2Right and Front2Back Spaces so for example your room is sized 10ft X 10ft, these gives you a diagonal distance of 14.1421 ft. Assuming there are no obstructions.
    1. REAR Left and Right Speakers
    divide 14.421 by the Left2Right distance resulting in 2.8842 ft right?
    round it off to 3ft (you could also be exact) now that would be the distance of the speaker with respect to the wall. The height of the rear speaker depends on your sitting height. So if you listen to the sound standing up the mesurement is different if you would be listening sitting down. So to make it work both ways. Let us measure the vertical distance of the floor to the roof, example you measured it at 10 ft, youre height is 6 ft and when sitting down about 4 ft. adding up your height sitting down to height standing up, results to the exact height of the room, add both and divide by 3 resulting in 6.667 ft. that would be the distance of the speaker to the floor. Now if one of the sides has a window or anything open or blocking the sound stage, the speaker placed directly there should be adjusted. Therefore the 3 ft distance calculated should be increased to 145% therefore multiply the 3ft by 1.45, resulting in 4.35 ft, that is the new distance from the wall.
    2. Seating Placement.
    Remember that your room mesurement is 10X10ft subtratc the total distance of the rear speaker distance to the wall would be 6 ft right therefore the remaining distance is 4 ft. Place your chair in between the two rear speakers that would be at 2ft from one of the speakers, and 4 ft from the back wall.
    3. FRONT Left and Right.
    Remember that you are sitted 4 ft. from the wall, so the remaining front to back distance is 6ft. Place the front speakers at this distance: 6 ft/2 = 3 ft then 6 ft. - 3 ft = 3 ft. then mutiply it by 2 which is equal to 6 ft. The diagonal distance from the center of the chair to the corner of the wall is 7.81 ft. therefore place the speakers at 6ft in diagonal distance from the chair.
    4. Center
    In Line with Left and Right Front Speakers and in the center.
    5. LFE(Subwoofer)
    Anywhere in the room, its not directional.

    Hope Ive helped,
    :thumbsup: Simplified, download software at http://demonhale.tripod.com
     

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