Why is a centre speaker needed?

Discussion in 'Home Cinema Speakers' started by Richard Barham, Nov 12, 2002.

  1. Richard Barham

    Richard Barham
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    Couldn't find an answer to this with a couple of searches, but I hope this is the correct place to pose this question.

    Can anyone offer an explanation of why the centre speaker in a 5-channel setup is regarded as being so important or even necessary?

    Surely a well set up pair of L and R speaker of reasonable quality should be capable of re-creating a satisfactory stereo image. This would also overcome the problem of siting the centre speaker, which except for projection systems, has always to be a compromise (i.e. it has to go above or below the screen).

    Not actually having had experience of 5-channel systems so far, I wonder if I'm missing a crucial point.

    Thanks
     
  2. Nic Rhodes

    Nic Rhodes
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    Basically the c channel pins the speach to the vision device so you don't have a picture in the the middle say and speach coming out the far left speaker. This just sounds odd. It is particularly important is you are not sitting in the sweet spot, i.e. off to one side. Also don't forget perhaps 75% of movie info is coming from the c channel. It is therefore VERY important to have a speaker that can cope. Unfortunately some people run in phantom mode (no c) or use a small c channel. Both are mistake IMHO (for all you TLA fans). The c channel is worth investing in.
     
  3. Flimber

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    Centre channel completely unnecessary in most domestic setups. Fact.

    HTH,

    Mike.
     
  4. uncle eric

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    I strongly disagree.

    The most active channel in a multi channel home cinema set up is the LFE channel. After this its Centre, Left and Right main equally, followed by the surrounds.
    In a typical sub sat set-up, most >80hz info is from the centre channel. One of the most important things to remember is that ideally, the centre speaker needs to be identical to the main L/R.
    I get a lot of stick from folks who for many reasons have not or cannot go with this but I always ask them to stop and think.
    When buying a stereo pair, would they accept a mismatch as in two different speakers. I think not.

    Centre channel (or lack of it) has been discussed on various threads at length, here is an interesting one started up by our very own Dom H.

    To save my typing finger, I've commented at length in this thread just why the centre speaker is so crucial

    http://www.avforums.com/forums/showthread.php?s=&threadid=48855&highlight=centre
     
  5. Nic Rhodes

    Nic Rhodes
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    I had a quick check of old post and unfortunately this is just one of many similar rubbish / meaniless / pointless / wrong answers Mike has given. I have had one post deleted already this week for saying what I thought without $ and * judiciously placed so I think it is best summed up by Eric.

    The above post is rubbish AND is NOT fact. :(
     
  6. Jeff

    Jeff
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    I would be happy to do without a centre speaker for stereo, prologic or 4.1 sound. Pity most of my DVDs are 5.1 DD or DTS. Phantom centre mode on my Denon A1SE is pants.
     
  7. MikeK

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    One of the most important things to remember is that ideally, the centre speaker needs to be identical to the main L/R.
    I get a lot of stick from folks who for many reasons have not or cannot go with this but I always ask them to stop and think.
    When buying a stereo pair, would they accept a mismatch as in two different speakers. I think not.


    Eric,

    I think you'll find that most people wouldn't dispute this in absolute terms.
    What they (me inc) most probably disagree with is any inference that you can't get good results UNLESS you have identical speakers across the front.
     
  8. Dom H

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    That sure was a fun one! :p

    To sum up my thoughts on the topic Richard I said I thought running without a centre speaker is preferable to using IMO inferior, mismatching dedicated centres. No one seemed to come up with a valid argument (unless I missed it) as to why dedicated centres are necessary (apart from off axis listening)

    I can't comment on matching speakers across the front as the sheer impracticality of it prevents me from trying it. This is probably the best solution thinking about it. Phantom and dedicated centres are BOTH a compromise, dedicated being by far the biggest.
     
  9. uncle eric

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    I think you're nit picking as usual here Mike.

    Good(depending on where you sit and other factors) but better (all things being equal) with a centre channel.
     
  10. uncle eric

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    I really don't know why I bother sometimes.

    Dum de dum de dum la la la. Should I rest my case. I think I will.
     
  11. MikeK

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    Eric

    What I meant was in terms of identical vs non-identical centre, not centre vs no centre. On that issue I agree with you! :)


    EDIT
    On reread, even that's not clear ;)

    I should of course have said "in terms of identical vs not quite identical" centre :)
     
  12. James45

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    if the centre channel is so 'pointless' why have 5.1? the centre channel is vital for 'locking' the dialogue to the action (ie the screen).

    this whole 'why use a centre channel' argument confuses me a little, it almost seems as though some people have a problem with multi-channel (ie 5.1) sources, if you want to listen to a stereo source through two speakers then fine but for 5.1 and above mixes the centre is pretty much the most important channel.

    eric's preference of having the front three speakers match just seems like common sense to me, and as he has already said a front (l/c/r) pan would sound odd if the the sound changed as it moved through the centre channel because of the centre's different tonal qualities. Personally I will be going for the same speakers all round as the same applies to rear-to-front pans IMO.
     
  13. juboy

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    Centre channel completely unnecessary in most domestic setups. Fact.

    A dedicated centre channel is as intrinsically vital in a 5.1 set-up as a left speaker is to a right speaker (or vice versa) in a two-channel, stereo set-up.

    Both will work (ie, you'll hear something) without the other but you won't be hearing what was intended for you to hear.

    You think state of the art cinemas run sound in stereo stacks either side of the screen and with some kind of 'phantom' or 'virtual surround' mode engaged? :rolleyes:
     
  14. Dom H

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    Dum de dum de dum don't get your point eric, so I thought Blade 2 had a poor soundtrack.

    Now Panic Room on the other hand has a fantastic mix, crisp dialog, subtle surround effects and good use of the LFE.
     
  15. uncle eric

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    The point is Dom that Blade actually has a great soundtrack with good clean dialogue. But you wouldn't know that as you've thrown that into the blender to be liquidized.
     
  16. Lowrider

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    I have, as most people, (I guess), a lesser center speaker, not bad, but not as good as the front speakers...

    I find that for CDs, using DPLII, I prefer to play without center channel, but for 5.1 sources, it always is better with it on... And I mean seating on the sweet spot... If you want to have a decent sound stage in a wider area, then the center is a must...

    I also agree that three identical speakers is the best solution, unless you use satellites, where, I think, a larger center might be better for movies...

    But, again as most people, I cannot place any speaker on, or underneath the TV, for starters mine are not shielded... And there isn´t a center matching mine... :(

    Anyway, after much searching, and testing, I found a very good center that matches "exactly" the timbre of my other speakers... Its on order... :cool:
     
  17. James45

    James45
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    you listen to CDs through prologic2 with the centre turned off? surely stereo would be a MUCH better option.

    And satellites are one of the easiest ways of getting matching speakers all the way round. guess it comes down to how good your sats are tho.
     
  18. Dom H

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    <slaps head> Doh! While I'm here can you tell me what I'll think of the star wars ep2 soundtrack, I'm renting it later, will I like it?
     
  19. CodeThief

    CodeThief
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    Are you being sarcastic??

    Don't take the **** mate, Eric is very helpful / knowledgable.

    Dave
     
  20. Guest

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    Just my £1.58's worth.

    With the advent of some top draw DSP parameters available on todays processors, i'd hate to be without a centre channel.
    When they are done right.....they are terrific.

    I love the centre for movies.

    I also love my centre for music duties too.
    I'm not suggesting this of anyone on here.....
    This is a general point.
    I still think there are some die-hard-no-going-anywhere-front-left-front-right-bog standard-stereo- types about...and will be for a while.....

    I love my 2 channel stereo.....but i also love these wonderful DSP
    weapons which we have at our grubby mits, which enable us to hear different tricks from those techie wizzards.....

    Long live the centre ground...

    Adzman.
     
  21. Lowrider

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    James,

    Maybe you should try DPLII with you CDs before you comment... Well, I don´t know your system, maybe you better not... ;)
     
  22. Dom H

    Dom H
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    He is indeed, he also doesn't mind a bit of harmless banter.
     
  23. James45

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    I have (otherwise i wouldn't have commented:rolleyes: )... along with Neo6 and circle surround and while DPL2 is light years ahead of the other two it still sounds terrible compared to stereo. Stereo was meant to be played through two channels and no dsp I have yet heard compares to straight stereo for CD music sources, dvd-a and sacd is another story tho.
     
  24. Dom H

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    IMO somewhat useless opinion I think musically speaking, the effect of a 3D soundstage created by PLII can be accomplished with only 2, well setup speakers. On the other hand complex 3D panning effects etc used in films are practically impossible to achieve with only 2 speakers.

    I find this only possible with the higher quality sources such as CD, radio & tv still benfit from the PL decoding.


    TV - Much better in PLII, especially if dolby surround encoded
    Anologue Radio - 2ch doesn't create much depth, PLII preferable
    Digital Radio - 2ch sounds better, sufficient depth/ambience
    CD - 2ch all the way, PLII muddles the sound
    DVD - 4.1 obviously!! :D
     
  25. Richard Barham

    Richard Barham
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    Looks like I disturbed a ratttle snake by posing the original question and it seems like the answers to my question were already dealt with in the thread that Eric kindly pointed me towards (thank you Eric).

    Can I just ask one more thing of those that are using a centre speaker. Is its position relative to the screen critical? Can you tell for example whether the speaker is on top or underneath the display (without looking of course). Does placing the centre speaker on the floor produce acceptable results (thinking of a plasma installation here)?

    (Hope this has not already been discussed, since my success with searching the forum has been poor so far!)

    Thanks
     
  26. Nic Rhodes

    Nic Rhodes
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    cough cough, Stereo was actaully designed to be a two channel system played through three speakers, yes you've guessed it a centre channel! But we won't get stuck on technicalities.;)

    There are dsp out there that can really benefit a stereo signal, TMS leaves the l and r completely untouched and adds VERY subtle c and rear sounds. There are others that are complete crap (hall, matrix, stadium etc). Adzman has trifield. Thats brill as well.
     
  27. James45

    James45
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    what manufacturers use TMS? not heard that one before. I've heard Trifield is amazing, now all I need to do is horde the annual GDP of several small African nations and I should be able to afford a system that features it!:D
     
  28. Guest

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    James.

    I think TMS stands for Tag Mclaren Surround......
    Have a guess where you'll find that?

    I think Meridian are the only bods (that i know of anyway) that have Trifield on their processors...

    I agree with the Beekeeper..........there are some excellent DSP's
    out there....they just need to change the view of the masses to get them to 'accept' these 'changes' to the traditional 2 channel
    (left & right) community....

    I'm off to have a Labatts Ice.

    Adzman.
     
  29. Nic Rhodes

    Nic Rhodes
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    They are the only one in the domestic field though there are a few professional licencees. It could be adopted by anyone however.

    TMS is Tag Mclaren Sound
     
  30. uncle eric

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    Richard,
    Disturbing rattle snakes is usually my job but I'll let you off this time ;)
    In answer to your question. The position of the centre speaker gets more crytical the larger the screen gets. As mentioned before, as part of a home cinema system, the idea being to get the centre pretty much nailed to the image and vice versa. In a perfect world, the idea is to have (at least) the front three speakers equidistant and on the same plane with the higher frequencies throwing sonics at you at ear height when seated. Many can't do this for various reasons (explained in the past thread).

    Another important aspect of centre speaker positioning is dealt with in a completely wrong manner by many installers.

    When given carte blanche to create a Home Cinema from scratch, many of these folks place the centre speaker slap bang in the middle of the room width. In other words. If a room is 14 foot wide (where the screen wall is) they place it centrally at the 7ft point and place the left and right either side. This is most definately incorrect as this sort of positioning will give all sorts of acoustic problems and will "push forward" problematic nulls and peaks in the average room. I always "shift" everything over to one side by say 6" to a foot to help lesson these problems.

    Going back to Plasma. I recently completed an install for my own living room using the new Panasonic W5 and speakers that shall remain nameless otherwise it looks like marketing again. I placed the L/C/R speakers underneath with the L/R being no more than around 8 inches wider each side of the plasma. The centre speaker being slap bang in the middle again underneath and all three on the same straight horizontal plane.
    I've seen some Plasma (or small screen) installs with the left and right speakers miles away from the display device or image. Some up to 8-10 foot away each side. Again this is incorrect. In a home cinema system, sound must be tied up with whats happening on screen. I would suggest that the L/R is fine at up to a foot wider than the screen width (Plasma or whatever). I certainly wouldn't go wider than this. Lucky for me, my fireplace is offset at the rooms width by around a foot so while the Plasma, hence front speakers all look nice and central, the fact is that they are not (as regards to the room that is).
    I'll post some piccys when I can pop out to buy another digital camera as my trusty old Fujitsu has died after 3 years good service.
    Best Wishes
    Eric
     

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