Center Speaker Sensitivity Problem

Discussion in 'Speakers' started by Alistair Paterson, Jul 3, 2003.

  1. Alistair Paterson

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    Hi,

    I have been having problems with my center speaker.

    The Audio is very quite/muffled when there is lots going on in a movie. For example in the Pod Race seen in Star Wars Episode 1 you can't hear the two headed commentators and some other audio during the race. You can hear them speaking but you cant make out what they are saying.

    I think the problem is due to my center speaker having a lower sensitivity rating than my fronts. I have tried changing the settings on my amp but it doesnt seem to make much diffrence.

    My center speaker is the Mission 77c with a sensitivity rating of 85db.

    My Fronts are Mission 774 with a sensitivity rating of 89db.

    Is this 4db diffrence likely to be causing the problem?

    I am thinking of changing my center to the Mission M5c with a sensitivity rating of 87db. Is this wise or do I need to find a center speaker that has a sensitivity rating closer to 89db?

    My system is as follows:

    Center - Mission 77c
    Fronts - Mission 774
    Rears - Mission 771e
    Receiver - Sony DB930

    Help would very much be appreciated.
     
  2. Jeremy Anderson

    Jeremy Anderson Screenwriter

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    Because the center has a lower sensitivity, chances are that you have to turn it up more in your receiver's individual channel level controls. Are you using a SPL meter to balance all the channels? If so, then you shouldn't have a problem.

    My situation is the opposite: All my speakers are 89dB sensitivity and my center is 91dB. Accordingly, I have my center level at -2 from the mains so that the level matches. I'm not saying that it's at -2 because there's a 2dB difference in the sensitivity... It's totally coincidental that it came out this way when using my SPL meter.
     
  3. Alistair Paterson

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    I have tried increasing the power going to my center speaker but it doesnt help much. Currently I have it on +8.

    I don't own a SPL meter so all my checks are by ear. I live in the UK and havent found anywhere where I can purchase a SPL meter at a reasonable price.

    Currently all my speakers are set to large as they can handle low frequencies with relative ease. I might try setting them to small tonight and checking if it helps.
     
  4. Terry Montlick

    Terry Montlick Stunt Coordinator

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    Hi Alistair,

    A sound level meter is not essential. Your ears are sensitive to within at least a dB when comparing relative sound levels.

    Can you get your center speaker to sound about the same level as your left or right, using a calibrated pink noise source, such as from an Ovation test DVD, or internal Dolby pink noise generator?

    If so, then your problem is an acoustical one, namely dialog intelligibility. This is independent of speaker - it's just that most of the time, dialog is mixed to go to the center channel.

    Poor dialog intelligibility is most commonly cause by a too-reverberant home theater. Any room playing a surround-sound movie needs to be relatively dead, with even absorption over the whole audio range. Commercial movie theaters achieve this by lining their walls with rigid or semi-rigid fiberglass panels.

    Every room is different, so it's hard to give an exact formula. But without the aid of acoustical testing, I generally recommend a mixture of mid-to-high frequency absorbers (1-inch thick fiberglass) and wide-band absorbers (3-inch or more) to reach down below 100 Hz. Many companies will sell you fabric-wrapped, rigid fiberglass panels. Count on covering a significant portion of the exposed wall area.
     

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