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EX with 4 KEF dipoles. Which goes where?

Discussion in 'Home Cinema Speakers' started by Jules, Jun 20, 2001.

  1. Jules

    Jules
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    I've just invested in a second pair of KEF
    TDM34 dipoles for my 6.1 system.
    Each pair came labelled L&R (I think so anyway, 'cos there's an L & R at the end of a number by the speaker terminals).
    But which driver fires which way on which speaker ?
    I think I remember reading on this forum that you should reverse the L&R speakers for the surround back channel. Is this correct?
    Does anyone have any useful info on this subject?
    I'd really appreciate some help. Thanks.
     
  2. Nic Rhodes

    Nic Rhodes
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    Ron? You seem to be in demand!
     
  3. Ron Locke

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    Hi Jules,

    Quite right, the 34's on the rear wall should be reversed.
    So as you look at the screen, the side dipoles are placed as they should be (L to the L and R to the R), whereas the rear set are placed L to R and R to L.
    Please ensure a safe distance between these speakers so to acheive the optimum effect.

    Regards

    Ron Locke

    KEF Audio
     
  4. Rob

    Rob
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    I also have a question regarding Kef surrounds.

    I plan to use TDM34DS as side surrounds and my existing Q85s for rears. Will these 2 work well together?

    Regards Rob.
     
  5. Guest

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    I now use 2 pairs of 24's in a manner similar to Ron Lockes advice and i must say, that all mis-givings aside i find them to be outstanding for home cinema duties, worth every (awful lot?) penny IMHO.
     
  6. Guest

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    34's even.
     
  7. Ron Locke

    Ron Locke
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    Hi Rob,

    The Q85S will be OK as EX surrounds, though ideally the TDM34DS would be my preffered choice.
    You have to realise that you are using two completely different speaker types, one that is giving you the feeling of having more speakers around you at rear (34's) and two that are direct radiated and easy to pinpoint at rear (Q85S).
    There is no problem using the Q85S, but this gives you a future upgrade path to the 34's at a later date.

    Enjoy !!

    Regards

    Ron Locke

    KEF Audio
     
  8. george1138

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    Rob. I have some 85s as back surrounds and they work pretty well (til I can afford some more 34s anyway :) ) but they need to be turned right down. Otherwise on descrete 6.1 material the backs can swamp the sides.

    Looking forward to another format with middle sides, top centre and top backs ;)
     
  9. Rob

    Rob
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    Thanks Ron & George.

    Better get saving then! I ve just upgraded my amps to some Rotels , 993 for my front end ( 3 x 200w) and 2 981s for surrounds ( 4 x 130w). I think 4 TDM 34s would be the best option overall. Unfortunately I need a decent processor first. Who said this hobby made any sense!

    Regards Rob.
     
  10. Black 5

    Black 5
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    I wouldn't have expected a great result from using dipoles for both side and rear speakers in an EX setup - if EX is designed to improve steering of sound (and the rear channel is mono I think) I would have anticipated dipoles would lose you a lot of the precise placement involved. Maybe what those users doing this are experiencing is a superficially impressive spacial sound, but one that was unintended by the sound editor??

    I suppose if it works for you, then why change?
     
  11. Phil Hinton

    Phil Hinton
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    Black,

    Actually Dipoles are the best type of speaker for this role as they raidiate the sound in the correct manner as was designed by the sound mixer. If you take a look when you are next in a suitably equipped cinema, you will notice that the surrounds are placed up the side walls and along the back wall. As this is how the sound mix is designed it makes it logical that you should use dipole speakers in the home. Dipoles give out the correct dispersion of sound to recreate the effect of having surround up the sides (and in ex/es to the rear).

    I recently saw Gary Rydstroms' (soundtrack mixer and THX EX inventor) home cinema set up, and what was he using as surrounds? Kef TDM's. I have lost the url but will post it if anybody wants a look at the feature.
     
  12. Phil Hinton

    Phil Hinton
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    What i forgot to mention is that you are not supposed to locate where the sound is coming from. Meaning you should not use "normal" speakers for surround duties. If the sound mix has a gun shot ment to be at the right side of the mix then using normal speakers you will hear it from wherever the surround is placed, whereas using dipoles and correct calibration it will be where it is ment to be.
    If that makes any sense as it is very early...Cheers
     
  13. jlcrawford

    jlcrawford
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    Can someone confirm that I am reading the post correctly and that you are supposed to cross over the extra pair of speakers in an EX setup ie place the speaker wired to LEFT output on the processor/amplifier on the side with the front and rear RIGHT speakers or do I have this wrong as it does not make sense to me.
     
  14. Black 5

    Black 5
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    THX,

    Totally confused by your second reply - you seem to be saying that you shouldn't hear the sound from where it's meant to be...or something?

    I've never heard of Gary Rydstrom, but I thought DVDs used a different soundtrack mix to the cinema soundtrack, because of the obviously different characteristics of the rooms and the need to optimise for people sitting all over a cinema rather than in a much smaller space in the home. Maybe I'm wrong.
     
  15. russraff

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    jlcrawford:

    I don't think you swap the cabling on the amp/processor, rather you just swap the speakers. So the cable running from the Rear Left still goes to a speaker to the rear left, but in this case, that speaker is marked as a Right hand speaker. I believe that the back speakers are reversed because of some "phase alignment" or something to create a more diffuse effect (please, someone tell me if I'm wrong on any count...)

    Black 5:

    I think that from a THX perspective, it makes sense that two pairs of dipole speakers are used. Lets say that you own a KEF THX speaker system. Set up as per THX spec, the "rears" will be to the side, not in the back corners of the room. As THX1138 said in his message, this is to replicate the multiple speaker arrays in the cinema. Now, as Dolby-EX is something THX had a big hand in, it is assumed that you have the side dipole arrangement, not direct radiators in the corner of the room. By using a direct radiator for the extra rear channel, you destroy the diffuse sound field of the side dipoles it is assumed you are using. Therefore an extra pair of dipoles are used instead, in order to further re-create a multiple speaker array of a cinema, and a more natuaral unfocussed sound. After all, you don't hear noises behind you from only two or three positions (speakers) do you?.

    The obvious differences between your living room and the local cinema is what THX is trying to achieve in the home. By purchassing suitable amplification and speakers, it is maintained by THX, that the sound you hear is closer to that in the cinema. This is under the assumption that the DVD soundtrack is unchanged from the cinema release.

    Sorry to go on,

    Russell
     
  16. museumsteve

    museumsteve
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    Sorry guys...
    I've read this thread a few times...and I'm rather confused about reversing the rear speakers...I have ES/EX with right hand speakers facing in towards the listening position, rear centres (stereo) and rear surround...Can someone tell me exactly what I should be doing with the speaker connections...I dont wnat to go over old ground..but I want to get the best out of my system..
    FYI I use a Denon AVCA1SE...and if you change the config during EX/ES what about matrix 6.1 and DD..does it affect it..??
     
  17. george1138

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    I think the short answer RE speaker connections is leave them as they should be, ie Left surround speaker in left surround connection etc. If you are using Dipole speakers just switch the back surrounds over (Left labelled speaker on back right and vice versa) Hope this helps a bit.

    Cheers
     

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