Two center speakers and comb filtering?

Discussion in 'Speakers & Subwoofers' started by JamesCB, Dec 30, 2003.

  1. JamesCB

    JamesCB Second Unit

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    Once in a while I see threads concerning the use of two center cahnnels. The usual answer from a few is a problem with comb filtering. They say two speakers with the same information will cancel out certain frequecies and enhance other frequencies causing problems with the sound.

    This makes absolutely NO sense to me. If the two speakers are close (within a few inches) to each other, I can understand that. Two drivers playing the same frequncies that are closer than the wavelength of the sound will cause comb filtering. But, using two centers would put them far apart (as in one above and one below the screen). Why would this be a problem? If I listen to a mono sinal on my two front mains, I don't get any adverse effects. I hear a single sound at the midpoint between the speakers, no matter what. Why would two centers be any different? I know putting them above and below or left and right would not make a difference. It's still a mono signal. Can someone give me a valid reason why this would be a problem?

    P.S. I will be posting this question in some other well-known forums for more responses. TIA for your replies.
     
  2. Patrick Sun

    Patrick Sun Studio Mogul

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    Human hearing is better suited for processing audio in a horizontal plane (unless they are sideways), thus 2 speakers on the left and right will do their magic for a properly engineered recording. With speakers in a vertical orientation, it's not going to sound as coherent (unless listening while sideways).
     
  3. John S

    John S Producer

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    I run two centers, and I definetly think the problems / potential problems associated with it are blown way out of proportions.

    Works well for me anyways, I have even swept with a tone generator, and found no such cancelling effects.

    I even run all channel stereo, and have found very little if any note-able cancellation at all.
     
  4. JamesCB

    JamesCB Second Unit

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    I see what you are saying. My audio dealer has his HT set up with two centers on either side of the screen. While I have not heard his setup, or one similar, he claims it works very well, though limited to the sweet spot.

    I had the idea of using an old stereo receiver for the centers. I would split the center RCA output to an input on the stereo receiver and run the centers from the L and R speaker out from there. That way you could use the balance to control the "height" of the image created by the two centers. I wonder if anyone has tried this?
     
  5. John S

    John S Producer

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    I upgraded my HDTV recently, I tried many different configs and center placements. I think I like having one on each side the best, I am just parallel'n them together. Pulls the center perfectly to the center as best I can tell. I have one seating postion rather forward and like 8' off of center, in that postion only it does seem to get pulled ever so slightly to that side, but you'd really have to be in a critique mode to even percieve it.
     

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