Center Channels a Gimic?

Discussion in 'Speakers & Subwoofers' started by Greg Racki, Mar 23, 2006.

  1. Greg Racki

    Greg Racki Extra

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    If quality two channel speakers, during cd-playback, can reproduce a soundstage that can place voices across the "front wall," supposedly very accurately, why do we feel the need for center channels in HT? I've read things stating that "without a center channel, voices will sound like they are coming from the corners." That doesn't seem to make sense given the way stereo speakers are very capable of portraying a wide and dynamic soundstage.

    I have Ascend 340ms and a 340c up front.

    I did this little test last night. I started playing the Phantom of the Opera DVD and went into the pioneer's set-up menu (while the audio was still playing). I listened for a while and then switched off the center speaker (channeling the center sounds to the left and right). It sounded way better with the center channel off, even when I placed the center channel in a more optimal ear-level position. Does this make any sense? The voices sounded less realistic and the music was far less impressive. I even played with the MCACC, which did little to remedy the problem.

    Maybe just the 340c isn't that good of a center channel, or something else is wrong, but I'm starting to think that I don't want a center in my system at all.

    Anybody agree or can tell me why I'm way off?
     
  2. AlbertD

    AlbertD Stunt Coordinator

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    This is a topic that has been much debated, with equal fervor on both sides. Some feel that a center channel is the most important speaker in the system. Some feel that it is superfluous, if the mains are high quality. Some, like me, are in them middle. I believe that any center channel is a compromise, at best. Having said that I have a center channel speaker in my system. I use bookshelf speakers, and a sub. A lot of the seating in my HT room is outside the sweet spot and I simply can't control that. So for me to have the dialog anchored to the screen, a center is mandatory. But...if I had high quality, full range speakers as mains, and did not have the limitation of people seated on the periphery of the room, I would bypass the center. I have experimented quite a bit and agree with you that properly set up mains, deliver a better sound (to me) without a center speaker. Albeit when seated in the sweet spot. When I build out my new system in my new home, I plan on using old Altec's, perhaps modified Model 19's as my mains and I will NOT use a center speaker. You will probably get some pretty good replies on both sides shortly.
     
  3. Jack Gilvey

    Jack Gilvey Producer

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    The main purpose for a center channel is to anchor dialogue to the screen for off-center viewers. Stereo speakers can't do that. My viewing area is about as wide as my front speakers, so center-channel information pulls to either side for those at the ends without a center.
    For MC music from the sweet spot, I could live with a phantom center, but 5.1 soundtracks are meant/mixed for dedicated centers, so I don't find any compromise there (aside from the typical compromises that a typical MTM "center" makes).
     
  4. Jacob C

    Jacob C Second Unit

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    Exactly. If you are sitting right in the sweet spot there shouldnt be much of a difference.
     
  5. Jack Gilvey

    Jack Gilvey Producer

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    It also brings up something of an irony: The bane of MTM centers (the most common type) has always been their off-axis performance. The spacing of the woofers causes some response anomalies as you get to the sides. Yet, the primary reason for the speaker is those off-axis listeners.
    I'm not too far off-axis even at worst, so my center stays pretty good, and the advantage in soundstaging outweighs any noticeable timbre issues (I imagine they'd be more noticeable with music, but I listen alone in the center for that).
     
  6. JeremyErwin

    JeremyErwin Producer

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    Some of the Living Stereo reissues on SACD were recorded in and are now available in 3 channel form. They should serve to demonstrate the advantages, if any, of a center channel.
     
  7. Kevin C Brown

    Kevin C Brown Producer

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    Most center channels have an MTM (midrange-tweeter-midrange) design. Like Jack mentioned, these designs are inherently flawed because if the 2 midranges produce the same frequencies, as you go off-axis, you will get interference effects due to constructive and deconstructive interference at lower frequencies. There are however a few ways designers can address this:

    1) MTM design where the drivers produce different frequencies, or at the very least, where the overlap is reduced. This is sometimes called a 2 1/2 way design.

    2) An MTM design where the tweeter is raised above the center-line of the midranges. The midranges can therefore be placed closer together. This does help with off-axis lobing, but it still a not a good solution IMO.

    3) Coaxial tweeter and midrange. Vandersteen does this. (I think KEF too.)

    4) Tweeter above single midrange. B&W does this among others.

    5) Woofer-(tweeter-above-single-midrange)-woofer design. This is one of the best ways, but it is more expensive to implement.

    One other thing, a lot of times center channels sound poor is because of placement. They are placed in the same rack with the display, or right below or above the display. Any large flat surface close to the center channel will result in unwanted reflections that can degrade sound quality.
     
  8. AlanZ

    AlanZ Screenwriter

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    Greg: I had the same experience as you did, except mine was more by accident. I haven't had a center speaker in four years [​IMG]
     
  9. JeremyErwin

    JeremyErwin Producer

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    I looked at your ascend acoustics speaker:

    mains

    center

    Oddly enough, the two pages use the same gif file for their plot.

    Please Note: All measurements taken with the speaker sitting atop a 32" TV with the front baffle flush to the front of the screen.

    uhhuh. right. whatever you say.
     
  10. Chu Gai

    Chu Gai Lead Actor

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    Back in the old days, when they were looking to move away from monaural reproduction, the people working on the project were looking at three speakers for a more realistic representation of recorded music. Quite a challenge with vinyl though!
     
  11. Dick Knisely

    Dick Knisely Second Unit

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    Personal experience is that as a music system stereo or quad is as good or better 90% of the time. One exception being the SACDs mentioned above. But for movies and TV the center channel is very important.
     
  12. John Garcia

    John Garcia Executive Producer

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    People seem to mention the off axis response a lot, but you have THREE speakers working up front. A well recorded track will have the sound properly dispersed across those three speakers and off axis response for the center should not be much of an issue.

    I use 5 identical MTMs for my HT. There is no off axis response issue with any of them. In a horizontal orientation, they are good to 30degrees off axis.

    Music is a different animal. Stereo music is recorded with the intention that there are only the two speakers, not intended specifically for use with a center. Multichannel music however, relies on the center just as much as movies or music DVDs. I find a center very useful.
     
  13. LanceJ

    LanceJ Producer

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    IMO if you don't have large crowds of people watching movies at your place, a center channel isn't a nessicity. Good speakers i.e. Bostons, JBLs, Athenas, or better can create a stable center image. As long as the speakers are even with the monitor's image, voices will eerily emerge directly from the center of the screen. When I ran my system without one, all the time people would go up to the TV & stick their ear to its speakers, thinking those were producing those voices.

    The only reason I have a center now is for 5.1 dvd-audio playback: even if my player could do it, I don't much like the idea of the player downmixing the center info to the left/right front mains because for hi-res music that might cause certain inaccuracies (this is just me being a little paranoid, so listen for yourself on your own system to decide [​IMG]). But for Dolby & DTS soundtracks and for TV & VCR viewing, my receiver is set for "no center".

    With music there *are* times that a separate center is sort of fun to have. On Beck's Guero dvd-audio (part of the deluxe edition), like most of Elliot Scheiner's mixes he very rarely uses the center for anything but will for an occasional special effetct. Like on the song "Hell Yes" during the chorus a woman rather softly says "please enjoy" - this emanates directly from the center speaker & it stands out starkly compared to when the phantom center mode is engaged when playing the Dolby Digital track (& it still sounds stark with Dolby & "yes center"). Crystal Method's Legion Of Boom has many more similar effects. But with my Simple Minds disc, Jim Kerr's vocals are only in the center but when seated, his vocal totally blends with the left/right fronts* and sounds no different than with the DTS track (receiver > "no center").

    Lastly, with music in particular it's not a good idea to have the center way up on top of a large monitor, then having the front channels sitting two feet down - this can disturb the front imaging & start messing with the "realness" of the music. And movies can also start sounding kind of discombobulated. This is why so many 5.1 music mixers don't use the center for anything becasue they don't know where the end-user will have his center placed or even if the center is of good quality.

    So if you have a pretty flat-screen plasma or LCD on a classy cherry stand, you don't HAVE to have a chunky box squatting on it to get good sound.

    * but the vocal reverb "trails" actually come from the left/right fronts; the vocal itself is completely "dry"
     
  14. mannyC

    mannyC Auditioning

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    you do not understand the recording process by sound engineers when recording a 5.1 surround on digitial processing. the intent purpose of the pro logic or center surround is to SEPARATE THE DIALOGUE from the left and right channels for intended purposes. MUSIC is another issue, but on home theater it's in the recording process, otherwise it's no longer theater sound!

    plenty of ominidirectional loudspeakers that create 3 dimensional sound. I happen to own several pairs like OHM, SRSLABS, OPTIMUS LINAEUM and sound processors that create them like carver sonic holography, acoustic research tds-202 enhancers and srslabs pro 220 spatial enhancer.
    For HT use the whole intention of the center is to completely separate the voice/dialogue recording from the rest of the signals. simple as that...if not having a center is your fancy that's your choice, then it's no longer a surround sound is it? it would just end up being a quad system like back in the 70's and 80's!

    other more profound omnidirectional designs are mirage, elac, duevel, german physik, mbl, ess and ess connoisseur, newform and many others, but these are all high end.
    the center sound you claim is nothing more than an illusionary sound but is not true digital surround.
    the speakers mentioned are nothing more than low fi to mid fi. can't even compare to what's in the high end world or audiophile world.
    if you want to argue your NO CENTER case on HT'S, go argue it with other professionals in the sound industry. Another good forum if you want to debate the purpose of center speakers would be ECOUSTICS, register there, lots of experts there. audioreview is another and audioasylum. I do not see any merits to your arguements of a center not being necessary to home theaters unless you are simulating a low budget low fi system to create an artificial surround sound to simulate the theaters?
     
  15. MikeNg

    MikeNg Second Unit

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    As mentioned before, the whole purpose of your system is to reproduce the source. If the source is recorded with a discreet center channel mix, then it would just make sense to reproduce that with a center channel. MOST movies are mixed this way, and as an ALTERNATIVE have a 2.0 mix. IMO that is not the preferred way to go with movies.

    Most music, OTH, is mixed as stereo, and the exception is mutli-channel audio (ala DVD-A).

    My completed system will have 5 surround speakers all the same (using MTM's at that) and dipole surrounds when 7.1 is initiated.

    To me, there is no 'set' answer to this. It all depends on what you listen to and the main purpose of your system.

    My 2 wooden pennies.

    Mike
     
  16. AlanZ

    AlanZ Screenwriter

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    Manny, I could not disagree with you more. I can assure you that the lack of a center channel does not mean you don't have surround sound. I can assure you that my Magnepan 4.1 set-up was very impressive. In fact, I challenge anyone to do better for the money. Quadraphonic sound is the same signal being reproduced by all four speakers. Having your mains handle the dialogue is a far stretch from quadraphonic sound. Nobody is debating whether or not a discrete center channel is created by DTS and DD....what is highly debatable is whether or not there is any difference in the audible presentation. To my ears, things sound better w/out the incorporation of a center speaker. If someone else prefers the center, then that's great! That's what makes this hobby so awesome. I think a lot of people feel like they are obligated to have a center speaker. Nothing could be farther from the truth.
     
  17. Evan M.

    Evan M. Supporting Actor

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    You bring up a lot of good thoughts and facts Manny but i also have to disagree with your basic sentiment. Is the recording put in 5.1 for a reason?.....of course and you are of course correct.....HOWEVER......when you say statements like this:



    .......you kinda lost a bit of credibility......
    You went from stating the facts to then saying in essence your way is the 'right' way and anything else is just 'wrong'. That does not hold a lot weight with a lot of people around here. You can't argue something that is so subjective as audio. As was mentioned before......the center anchors the dialogue for off axis listeners....."simple as that". I have heard many systems with a "phantom center and have been blown away. Was it how the recorders intended it to be listened to?.....probably not......Did it sound just as good and if not better than MANY 5.1's I have heard?....Hell yeah. With all that said.....I do have a center channel and absolutely love it......now if I had AlanZ's Magnepans things might be different [​IMG]........
     
  18. AlanZ

    AlanZ Screenwriter

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    Heck, Alan Z doesn't even have Alan Z's Magnepans anymore, lol....but they sure did a helluva good job for me while I did have 'em [​IMG] [​IMG]

    And I totally agree with the way you said it....above all else, audio is subjective....everyone should take the time to find out what most appeals to them, and allocate their funds accordingly.
     
  19. LanceJ

    LanceJ Producer

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    Wow.

    As far as Boston Acoustics, Athena and JBL not being comparable to what's in the hi-end market....whatever. No, (most) don't usually come with exotic veneers and materials that sound like something on a Star Trek episode. But then again, from what I can tell much equipment labeled "hi-end" are simply systems that were designed using software bought from somewhere like PartsExpress then built with needlessly thick cabinetry & adorned with mystical names pulled from a Shakespearean play - that way they can be priced 10X or more what they are actually worth.

    Intentionally rolled off high frequencies parading as "velvety smoothness" & non-existant and/or pinched bass sold as "accurate low end" are not true high fidelity.

    I don't usually say things like this because I can't prove them on an Internet forum, but I KNOW my $425 Boston CR9s have excellent stereo imaging and can create near-pinpoint center images. Same with the other brands. A B&W N802 can do this better, but I had to concentrate to notice this increased ability......and to me it is not worth the extra $7,650 over my own speakers' price.

    I've noticed over and over how many people here have never "stooped" to listening to anything that doesn't have a fat price tag or some slick manufactured pedigree (and to make the cheaper gears' image worse, this gear is almost NEVER set up right so one can hear it properly). Sorry, but the technology to design and build true high fidelity speakers is no longer a secret. 95% of the research and development for this was done years ago, is paid for and has been available for a couple decades to those "mid-fi" companies and even quite a few lo-fi ones as well.

    BTW: quad IS surround. The center channel and subwoofer in modern 5.1 systems are enhancements of the surround soundfield in the form of lower/better bass and dialog anchoring. The surround soundfield is generated SOLELY by the interaction of the front left/right and the rear left/right speakers.

    And just like surround mixes today, each quad mix (all 3,500 of them) can have a different mix and most were very discrete, using four different signals. The confusion about this may be caused by the fact that two of the most popular vinyl-based quad formats, "SQ" & "QS", were matrixed* formats and didn't always decode very well, especially with lower-priced gear (remember, this was before the days of cut-n-dried digital decoding processes). JVC's CD-4 vinyl process, the reel-to-reel and cartridge-based Q4/Q8 formats were the truly discrete four channel formats. But just like with most of Silverline's and Sony's DualDiscs with their IMO crappy DSP-derived (that's what sounds like what's happening to many people who have heard some of them, including myself) "surround" mixes, the blurry sounding matrixed formats were much more prevalent than the discrete formats and for good reason didn't impress many people & the cartridge formats just didn't sound that great period (they used very narrow tape) and quad finally quietly died by @1980.

    You can read more about this here: Quadraphonicquad.com

    If someone wants to hear how good quad can sound, listen to Dark Side Of The Moon in quad. I've heard a DTS-CD version made from a quad tape and the mix is fun as hell, and many people like it much better than the sacd's rather timid mix.

    * vaguely similar to Dolby Surround but with two different rear channel signals
     

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