Center Speaker Sounds Empty

Discussion in 'Beginners, General Questions' started by Adam J, Jun 18, 2002.

  1. Adam J

    Adam J Stunt Coordinator

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    Hi,

    This may be because I am running a budget system. I have the Polk RM6000 Surround speakers and an HK-120 receiver.
    What I notice is that on DTS and DD5.1 Soundtracks, the vocals are sent to the Center Channel. This is normal.
    If I listen to the same DVD in Stereo or DPLII the voices sound much fuller to me. I also can switch between my TV speakers and the Receiver playing DTS or DD5.1 and the TV Vocals will actually sound better to me.
    I borrowed my friends JBL center speaker and I could not detect any difference between the Polk and JBL center while listening to dialogue.

    I think I will go to Circuit City to try and compare my Center with a couple of the more expensive models to see if I notice a difference.

    Just wondering if anyone else noticed this, is it a common response when people compare the single channel vocals on a center channel to the stereo mix?
    Maybe nothing is wrong with my speaker and this is just a difference in the 6 channel formats compared to a stereo mix.

    Also I should clarify that this only concerns the dialogue, the rest of the sound is great. Thanks for all replies!
     
  2. Michael Reuben

    Michael Reuben Studio Mogul

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    How much power does your receiver have for the center channel? Is it equal to what it uses to drive the front left and right?

    Have you balanced the levels of all your channels, preferably with a sound pressue level (SPL) meter? It's possibly that your center channel is too low relative to the other channels.

    Just some possibilities to consider.

    M.
     
  3. John Garcia

    John Garcia Executive Producer

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    What setting do you have the center set to? Large or small? This could be a factor.

    I'm going to guess that this is something to do with setup, and as Michael points out, the first thing to check is the speaker level setting. Ideally, you want to do this with test tones and an SPL meter, but you can ROUGHLY do it by ear also (though I don't recommend trusting your ears in the long run).

    Also, if there are any other configurable items for the center channel, try changing them to see what effect they have.
     
  4. Wayne A. Pflughaupt

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  5. Glenn Overholt

    Glenn Overholt Producer

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    Adam, try all you want, but you'll probably not get anywhere. I am convinced that it is the DVD's themselves. The sound mixers are cranking up the sounds while sacrificing the center channel.

    It is not present on every disk, but the best way to 'fix it' is to turn your center channel volume up - more than the other channels - and/or even turn the other channels down.

    You can calibrate your sound on a calibration disk until hell freezes over, but the fact remains that if the sound engineers did a sloppy job on a DVD, then the only true calibration would be to do it for every disk.

    The rest of you may argue all you want to, but the lack of a center channel sound that is adequate on just some DVD's only tells me that unless I changed my hearing range or my receiver's settings, (which I don't normally do), the only other explanation is that it must be the DVD.

    Glenn
     
  6. Michael Reuben

    Michael Reuben Studio Mogul

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  7. Adam J

    Adam J Stunt Coordinator

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    Hi All,
    Well as a member of this forum, I have the Avia test disk and the SPL meter and spend the first couple weeks moving speakers around and setting volume levels. So thanks to all of you for the basics I already have under my belt.
    Center = Small
    Surrounds = Small
    Right = Large
    Left = Larger
    Sub = Off
    (This is how Polk suggests setting up these speakers)
    http://www.polkaudio.com/home/faqad/...cle=bassmanage
    I've already contacted Polk about this issue and from my testing I am confident the speaker configuration is not the cause. I have switched the Right and Left with the Channel and notice no difference in sound, at least not any improvement.
    I believe my problem is either the 3.25" midrange speakers as Wayne Suggests. The Center has 2 of these but maybe they just don't have the size to do voices justice.
    Or what Glenn Overholt suggests, which is what I really was curious to know. How many other people experience this difference between Stereo and DD5.1/DTS. I guess my real question for all of you is do any of you not notice a difference when playing movies in stereo vs. DD5.1/DTS. If your Stereo signal does not sound better for the vocals, then I will take that as a good indication that the problem is with the size of my center speaker, and not just the difference between the stereo mixing of the dialogue and a single center channel.
    Thanks for all your replies, I will let you know what I find out when I try the better speakers at Circuit City.
     
  8. John Garcia

    John Garcia Executive Producer

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    Yes, the most likely cause is the size of the drivers. Personally, I don't think anything less than a 5-1/4" driver (in a well designed speaker) and preferably a 6-1/2" driver is needed for any realism. This more true for music than movies, but is still true with both.

    First, NONE of the speakers in that package can take a full range signal, so none of them should be set to large.

    What you really want to look for is the low frequency extension, and match that to the crossover point of your receiver. What you want is approximately one octave coverage below the crossover point. So if the crossover is 100Hz, you need a speaker to cover at least to 50Hz. This is the reason why HTiBs and tiny speakers do not live up to most people's expectations - they are actually leaving you with gaps in frequency response in the lower midrange because they are not capable of reproducing those frequencies well.
     
  9. Adam J

    Adam J Stunt Coordinator

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    Hi John,
    I take your words as truth. I am however happy with the speakers, and those set to "Large" are actually run through the Sub and the Sub handles the bass management. That is described in the Polk weblink.
    I have no doubt that there may be some midrange signal loss if you say so, but I really don't notice it. The only time I have any issues is with DTS/DD5.1 soundtracks and the center speaker dialogue. Other than that I am very happy with my speakers. Ignorance is bliss afterall [​IMG]
    I think what you are saying is a direct answer to why my center channel does not sound satisfying though. I take from your reply that you are happy with your center channel on DTS/DD5.1 soundtracks so I will probably just end up buying a better center channel.
    Then of course I will be unhappy with my L and R speakers in comparison with my new center, and after 5 years of upgrading I will finally be replying to a newbie like me with the exact same response you just posted [​IMG]
    Thanks for the info! I plan on buying a good system when i reach 40, it is my 30th birthday today actually and this system will have to do until then. Thanks all for the discussion, very helpful, I am gonna go center speaker shopping for a bigger midrange speaker and see if I hear a difference.
     
  10. Michael Reuben

    Michael Reuben Studio Mogul

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  11. John Garcia

    John Garcia Executive Producer

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  12. Adam J

    Adam J Stunt Coordinator

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  13. chella

    chella Stunt Coordinator

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  14. Glenn Overholt

    Glenn Overholt Producer

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    Adam, why don't you swap the speaker cables for your center with one of the fronts, just to see if the center is now better? Could be cheaper.

    Glenn
     
  15. Adam J

    Adam J Stunt Coordinator

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  16. Greg_R

    Greg_R Screenwriter

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    This sounds like you've got the polarity reversed on your center channel. Stereo sounds great (since the center is not used). When you listen to 5.1, the dialog sound empty and unfocused. Something is out of phase... check all of your speaker connections. Of course, a bad center will not help matters...

    BTW, the imaging from your main speakers will outperform the center channel. The purpose of the center is to anchor the dialog to the screen for those viewers who are not sitting in the sweet spot. If you sit in the middle, "phantom center" mode should sound better.
     
  17. John Garcia

    John Garcia Executive Producer

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    Hmmm. I hadn't thought about polarity, however, if it sounded the same when you hooked it to the R/L wires, that should not be it. However, that got me thinking about other factors, such as your 5.1 settings. What are the settings on your DVD player? If you have it set to downmix or PCM, you may not actually be getting 5.1. Does the receiver say that it is receiving 5.1 signal? When I bought my new player, it was defaulted to D-PCM for the digital connection, and it sounded odd. It took me a while to figure out that this was happening, but I got it when I looked at the receiver's display, which would only give me DPL/PLII for what should have been 5.1 tracks.

    I guess this should have been asked also - what DVD player are you using and with what connection?
     
  18. chella

    chella Stunt Coordinator

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    Polarity crossed my mind too, but I would not have expected you consistently make the same mistake - with JBL too. Have you tried changing the center speaker position, below the TV, aiming up or down, etc. Trying out with other models will definitely give you a sense of direction to a solution.
     
  19. Adam J

    Adam J Stunt Coordinator

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    I originally had my center on the shelf below my tv. I have since bought some velcro and moved it on top of my tv (Screen ledge is not very big and one of the reasons I wanted to go with the smaller speakers). That really didn't fix the sound problem. I originally thought that was the cause of the problem.

    The avia disk didn't detect any polarity problems, and I even tried switchin the wires just in case, but it didn't really make a difference to my ear to be honest. Maybe that is a problem in itself...

    Definitely getting the 5.1 signal. I have a PS2 and a Sony DVD player hooked up and both will detect 5.1 signals. Both connected with Optical cables.

    I even had to run brand new speaker wire when I moved my speaker from below the TV to above it, so I double checked the connections at both ends at this time. I even considered the possibility that my receiver may have been labeled wrong, but switching the wires around at either end should be enough to test this and as I stated, I didn't notice a difference.
     
  20. Adam J

    Adam J Stunt Coordinator

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    Problem Resolved!

    The Harman Kardon 120 does not send the Bass signal to the L and R speaker with the following setup:
    Left = Large
    Right = Large
    Center = Small
    Surrounds = Small
    Sub = None

    The center Seaker sounded a bit empty or hollow because the bass signal was being lost.

    I found this out by buying an RCA cable and hooking up the Sub in the normal configuration rather than how Polk suggestions:
    Left = Small
    Right = Small
    Center = Small
    Surrounds = Small
    Sub = Yes

    Now the Right and Left do not sound as well blended as they did in the previous configuration. There is an improvement setting up the speakers as Polk recommends, however with my receiver (Other receivers may not do this) the Center Channel Bass signal is not re-routed to the Left and Right speaker when there is no Sub. It is still sent to the Sub (Which isn't there).

    Anyhow, after making this change I find my L and R speakers sound about 89-93% as good as they originally did, and my Center sounds 35% better.

    I am happy now with my system, small midrange loss speakers and all. I think everything sounds great.

    I would guess that Polk tested these packaged surround speakers with some other receiver(s) that did not lose the bass signal when configured this way, and it wasn't really noticable on mine unless I was listening to 5.1 soundtracks.

    This also explains why my friends JBL speaker sounded the same as mine and DPLII sounded great in comparison.
     

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