+/- 3dB?

Discussion in 'Archived Threads 2001-2004' started by Brad O, Mar 27, 2002.

  1. Brad O

    Brad O Auditioning

    Mar 10, 2002
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    There is so much information when it comes to home theater and electronics, to some this might be a stupid question.

    I am curious to know whether differences between speaker efficiency can be or should be adjusted through your receiver’s speaker setup. Such as if the front and rear speakers have a 95dB efficiency rating and the center has a 98dB rating. Should I adjust the center to –3dB or the front and rears up to +3dB, or doesn’t it matter?

  2. keir

    keir Stunt Coordinator

    Jan 16, 2002
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    doing it by ear is probably enough. if the center actually sounds louder with your receivers noise generator, then i would turn it down to match the others. i am not so sure that the specifications are taken in exactly the same manner, and that they can all be directly compared that easily. but if they are the same manufacturer then i bet -3 for the center would sound about right. anyway, what you hear is the most important.
  3. Bob McElfresh

    Bob McElfresh Producer

    May 22, 1999
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    Hi Brad. Welcome to HTF! [​IMG]
    While your therory is good, I'm afraid you cannot just look at efficency numbers and adjust the levels.
    You see, your different speakers sit different distances from you. Some speakers point directly at you, other focus in front/to the side.
    Each of these will have an effect on the volume.
    The traditional way to solve this is to buy a Radio Shack SPL meter for about $40 and use the built-in test-tones or a setup DVD like Avia/Video Essentials to adjust the levels.
    The simple idea is this: put the SPL meter in your center seat. Start the test tones (which will come out of 1 speaker at a time) and wait for either the L/R front to make sound.
    Adjust the main volume control up until the meter reads "75 db".
    When that sound moves to the center, you use your receiver remote to add/subtract some sound from the center until it also reads "75 db".
    Repeat for each of the rears.
    Yes, this is a "adjust it after it's built" approach, but it really is the simplest.
    Search for "Calibration" and you will find lots of discussion/details on how to do this.
    Good Luck.

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