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Second centre speaker

Discussion in 'AV Receivers & Amplifiers' started by fred123go, Oct 9, 2003.

  1. fred123go

    fred123go
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    Hey all,
    my system is as below, how could i add a second centre channel, so producing two mono sounds.
    Would i add a stereo amp and connect it via one left analogue cable and just add one speaker to its outputs, or is this completely wrong?
    Cheers all
    Fred
     
  2. Soni

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    Why would you want another centre speaker ?

    Cheers

    Soni
     
  3. narabdela

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    Why indeed ?

    :confused: :confused: :confused:
     
  4. meep

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    I've seen a few installs where two centre speakers are placed either to each side of the screen or above and below.

    The logic is that this arrangement fixes the center channel audio to the centre of the screen.

    Of particular relevence for large screen (projection) installations where sound-transparent screen material is not used.

    It takes all sorts!

    Peter
     
  5. Ed Selley

    Ed Selley
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    You could run a 7.1 THX pack with two 504 centres but it is quite cumbersome in relation to the improvement garnered. If you were after 7.1 with the 500 series sell the second centre and buy an extra pair of 506 dipoles. If you wish to use a monopole design, the 912 is a better (and cheaper) bet than trying to mount another 504.
    Ed (Mordaunt Short)
     
  6. S H A D O

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    Two centre channel speakers can have more problems than benefits due to cancellation of frequencies etc etc. You're better off sticking with one decent centre channel speaker instead and saving yourself the hassle. :)
     
  7. fred123go

    fred123go
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    Cheers for the replys guys, i just thought, as they have in the cinema, that another centre channel would make films more spacious and more realistic. If it is not worth it then i would stick to just the one but in a room with a very big 8ft screen one either side or indeed behind the screen would be beneficial.
    any thoughts?
    cheers all
    Fred
     
  8. meep

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    Fred

    The idea position for the center speaker is behind the screen at the same height as the l/r speakrs.

    This is not always possible due to space restrictions. Also, for a speaker to work behind a screen, the screen fabric must be acoustically transparent. That is to say, a screen material with thousands of tiny holes to let the sound through un-impeded. (Some say this effects picture quality adn I am not experienced enough to comment).

    Often, the comprmise is to place the center speaker directly above or below the screen, titled at a slight angle to compensate for vertlicl placement differentials with l/r speaker.

    The downside of this is that the center channel is not locked vertically to the center of the screen (though in most cases this would hardly be noticed - particularly if your centre speaker was a decent vertical dispertion (which I think THX rated units are designed to have in any case, no?)

    Some installers will place two center speakers to lock the image to the center but as already noted, this may give rise to additional cancellation problems and probably is more trouble than it's worth.

    Again, you'd need someone with a little more expeience of aucoustics to comment further on this point.

    Regards

    Peter
     
  9. thackl

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    Fred,

    I have a system with two centers. It fixes the sound on the screen and I have had no problems with cancellations etc. I found that it is still better to have the bottom one slightly louder than the top. Amplification is provided through splitting the pre-out, go into right & left of the DSP-E390 and have the internal pro logic decoder put the signal back together again. I know it sounds strange but works a treat. To gether with the front effects channels on the Yamaha it goves me an extremely wide soundstage from left to right and floor to ceiling where the relevant sound come from the screen and not the speakers.

    Cheers
    Tom

    Photos are here

    http://members.optusnet.com.au/~thackl/gallery.html
     
  10. nathan_silly

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    Holy ****! I thought my room was full of speakers. How/why are there so many speakers?
     
  11. narabdela

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    I think I need to go and lie down in a darkened room for a while.

    :eek: :eek: :eek: :eek:
     
  12. thackl

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    Hi Nathan,

    The system has already 9 channels. I only duplicate the front center as one center really sounds like voices coming from a black hole. The rear centre is multiplied to achieve a better dispersion (similar to a 7.1 system) the sides/rears have an array (2 floor, 2 ceiling, 1 filler) to achieve the same and also better match the front. Two subs are used to even out room modes. All in all the purpose is to avoid speaker localization which can also be achieved through di/bipoles however I find this more effective and simply 'bigger', more lifesized and natural in sound. Just to give you a recent example, the other day we watched Knockaround Guys and it has a scene towards the end where an actor steps out of a building into the street. At this point the traffic is all in the rears and me and my wife jumped as we thought we would be run over by cars driving over the couch.


    Cheers
    Tom
     
  13. fred123go

    fred123go
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    hey all cheers for the response,
    Ok so the second centre was not a good idea, but what thackl has done looks very interesting and i am sure it sounds great, and btw top class room mate!
    One quick question, if i wanted to get an extra set of surround left and rights could i use a normal 2 channel power amplifier, like the nad c270, http://www.nadelectronics.com/hifi_amplifiers/C270_framset.html , would that work or not?
    thanks all
    Fred
     
  14. thackl

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    Hi Fred,

    you certainly can. Usually 2 channel integrated or power amps have a much better damping factor than AV receivers anyway. The only problem you may run into, and that's the reason why I chose integrated amps, is that you cannot control the volume independently. Any additional set of speakers will need to be volume controlled independently from the master volume to make it blend into the soundfield. I have spent a lot of time on this to create a cohesive environment. The NAD has fixed and variable (unchangeable and changeable with master volume) but no independent output control. The volume issue may work out well by default but if not, you would want to have control over the loudness of any additional speakers apart from the original 6 speaker set connected to your AV amp.

    Cheers
    Tom
     
  15. fred123go

    fred123go
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    hey again,
    I have decided to go through with adding more speakers to my system, what i would like to do is too:
    1 add one surround receiver to drive an extra set of rear l/r speaker, or more not sure yet
    2 have another stereo amp to power two surround back speakers.reason for this is because i want to use to 6th and 7th channel on my vsx-d2011 to bi-amp my fronts.
    then i think i will have a very very nice set up indeed
    but one thing tom:
    if i am using a stereo amp for the surround backs will this give the correct l/r surround back steering i would have if i used my receiver?
    cheers
    Fred
     
  16. Steve.EX

    Steve.EX
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    When i used to own two coffin sized main l/r speakers (160x45x55cm approx) i was consistantly aware that the pannig of vocals etc was clearly moving from a v. large baffle to a small baffle to a v. large baffle.
    Installing two centers one above the (then) TV and one below really helped flesh it out, then gains IMO far outweighed the negatives.


    this has now somewhat changed in recent times of course.
     
  17. thackl

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    Hi Fred,

    If your Pioneer has separate pre-outs for surround back left and surround back right there won't be any problem as all the processing will take place in the Pioneer's processor.
    Be careful with using surround amps to add speakers. Often they only switch on all speakers when using a DSP program (like Yamaha). As you will need to leave your volume up (at least halfway or even more) you will hear a lot of noise from the DSP when the soundtrack is quiet or nothing is playing. As a result you can only use them like a 2 channel stereo amp and that's where the dedicated stereo amps are much better

    Cheers
    Tom
     
  18. fred123go

    fred123go
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    thanks a lot Tom mate,
    Ok, i think i have made my final decision, two stereo power amps from Rotel (2 Rotel RB-1070 power amps)http://europe.rotel.com/products/specs/rb1070.html - i think thats the link. If power amps do not have a vol dial then how is the volume determined?would it be by my 2011?
    cheers
    Fred
     
  19. thackl

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    Hi Fred,

    yes, the volume will be controlled by your Pioneer. It always will, even with integrated amps. Just think of a poweramp as an integrated amp with the volume set to full. For the surround backs that's fine as they don't add to another speaker, they represent a 'first speaker set' for a channel by themselves. When you add more rear surrounds however you may come across the problem I mentioned earlier where full volume will just be too loud and without a volume control on the amp for the additional speakers you can't turn them down to blend in. You always can move the speakers further away, depends on how much room you have to play with. The whole thing takes time and a healthy dose of trial and error and of course you 'need' to watch lots of movies to experiment with all sorts of locations and volume settings.

    Cheers
    Tom
     
  20. fred123go

    fred123go
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    cheers Tom,
    I will be looking to get all the equipment by december time so plenty of time to experiment with borrowed kit till then and btw how did you manage to get your main yamaha amp as it has not been released yet in England, is equipment and dvds released earlier over there?
    cheers for the help!
    Fred
     
  21. thackl

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    Hi Fred,

    My main is a Z1 and that's been out for a while. I'm not upgrading to the Z9 as I don't need all that fancy video processing (got it all in the Marantz and I don't watch TV much) and also it doesn't have DVI or HDMI switching which is an absolute must for future proofing (HDTV, maybe DVD-A and SACD, firewire may be superceeded soon...). Usually gear is available around the same time as anywhere else in the world, but due to a small market and import duties we always pay more than in the US or Europe

    Cheers
    Tom
     
  22. fred123go

    fred123go
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    Cheers for the info Tom,
    Not many of the z1's around, they look very good though, i might be upgrading my receiver anyway and it looks a very good performer, on paper, would you reccomend this amp strongly then? Although my 2011 is a great sub 1000 pound receiver i just feel i could get better sound through a more expensive amp
    cheers
    Fred
     
  23. thackl

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    Hi Fred,

    I love it and can only recommend it. I am happy with the 2-channel sound and think it is the best sounding Yamaha in that department so far. Yamaha also has great DSPs (based on their research into accoustics for highly regarded reverb/effects units in the professional audio field) although I don't use/like them for music (except PLII which is not really a DSP) I think they are great for films (the Z1 also has a higher resolution on these than cheaper Yamahas). They can increase the size of your room and simply produce a much more cohesive soundfield especially when using multiple speakers as I do. This is important if you want to recreate the sound of a multi speaker set up like in a normal cinema. Best of all however are the front effects. In a cinema you normally have the mains behind the screen. To achieve the same effect at home you have to use a microperforated screen with the mains behind it and that is usually very difficult audio and video wise, let alone space wise. To put the mains at the left and right side of your display works with TVs but as soon as you start using projectors and larger screens, the display also stretches vertically and your speakers will still only produce sound on one horizontal plain. That's where the Yamaha front effects come in, they give you another two points above your mains where the sound is anchored so you have a total of four points outside the screen between which the sound can move. This recreates the impression that the sound is emanating from the screen (and IMHO necessitates the use of another front centre). You should go to a dealer that has this properly set up and get a demo and with the Z9 arriving there should be good run out deals available

    Cheers
    Tom
     
  24. fred123go

    fred123go
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    i think i am going to go speaker mad in a few months, i don't think i can afford the z1, not at least till next summer, but i can buy about 4 yammy AX396s' and two extra pairs of surrounds, an extra 2 fronts (great idea from yammy) and maybe an extra centre.
    Cheers for all the help mate
    Fred
     
  25. thackl

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    Hi Fred,

    Be aware that the Yamaha front effects are not an exact duplicate of the front signal they sort of simulate early reflections and are derived from the main left/right signal through DSP.
    You are right that you can easily buy lots of smaller stereo amps second hand for very little. Did exactly the same with all my additional amps.

    Cheers
    Tom
     
  26. fred123go

    fred123go
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    Hey tom,
    thanks for that, actually i will probably have more use for them if i put them like further apart from where the fronts are now so to reproduce a much wider sound stage, really all depends how my first experiment with the new pair of surr r/l's go, oh yeah are you actually using that room as a commercial cinema basis, do you have people who pay to watch a film or not?
    cheers
    Fred
     
  27. thackl

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    No paying customers (yet, copyright laws;-)) but people usually bring 'tickets' in form of drinks and snacks so we always have a great time.

    Cheers
    Tom
     

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