Decoupling Center Channel Speaker from RPTV: An Observation

Discussion in 'Archived Threads 2001-2004' started by Jeff Drumm, Jan 4, 2003.

  1. Jeff Drumm

    Jeff Drumm Extra

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    This is more an observation than a question, but I am interested in others' experiences.
    I just received my JBL S-Center II yesterday (replaced a cheap Pioneer freebie that came with my receiver). I plopped it on top of my Hitachi 57SWX20B, adjusted the level to match my mains, then proceeded to suffer a bit of a let-down because of the "boxy" sound I was getting from it (yes, the sound was boxy from the Pioneer as well, but it was also inferior in other ways).
    I acted on a hunch and relocated the S-Center to the shelf immediately above the TV, completely decoupling it from the TV's cabinet. My theory was that the screen of the TV would function as a large radiative surface and might be resonating at certain frequencies transmitted from the S-Center's cabinet into the TV's.
    The improvement in sound quality is very apparent . . . the boxiness has disappeared; for that matter, I can detect virtually no coloration from the speaker after the move, and am much happier with my choice than I was initially.
    Does this seem odd to anyone? I searched through this forum for corroborating experiences and couldn't really find anything . . .
    --
    - Jeff
     
  2. Bob McElfresh

    Bob McElfresh Producer

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    Hi Jeff.
    It's been a while, but here are some of my typical suggestions for mounting your center speaker:
    - Make "Feet" for the center speaker to get it up off of the TV top or shelf. You can use wooden dowels, pink-rubber erasers, paper back books or (a popular choice) rubber door wedges. The door wedges have the advantage of being stable and give the center speaker a downward tilt. This often compensates for the center tweeter being physically higher than the L/R tweeters. (Use a laser pen to "see" where the tilt is hitting the central listening position.) Some people have even spent the $7 for a wheelbarrow innertube and half inflated it to put under their center speaker.
    - Pull the face of the center speaker forward so it over-hangs the TV face by about 1/4 inch. Even with feet, if the face of the speaker is flush with a RPTV, the front of the TV will acoustically couple to the speaker. Bringing the face of the speaker forward will break this.
    - Never push the center speaker back to form a small shelf in front. This will create a reflecting surface that will reflect quite a bit of sound energy upwards to later hit your ears after bouncing off the ceiling. This is considered distortion.
    - Some entertainment centers have a cubby for a speaker with black cloth over the front to 'hide' the speaker. This is like rocks rattling in a tin can. But if your spouse insists, try this: stuff the area behind the center speaker, and even around it/under it with some soft blankets/towels. You are try to muffle the sound bouncing around inside the cubby producing a boxy/echo sound. A quilted "Cargo Blanket" from Costco/Sams Club does a great job for this.
    Others have had trouble putting the center speaker on top of their TV. They have found that building a small stand and placing the center on the floor in front of the TV with a bit of upward tilt actually produces a SUPERIOR sound compared to the center-on-top placement. If your spouse/family/pet situation allows this, give it a try. Even if they dont, try it anyway some empty weekend afternoon. (What happens while the spouse is gone stays between us. [​IMG])
    Hope this helps.
     
  3. Jeff Drumm

    Jeff Drumm Extra

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    Thanks, Bob. Excellent information, and gratifying to hear that what I observed was not unexpected. I can't help but wonder, though, how many people have done just what I did initially and assumed that the sound they got was what they were supposed to get . . .
    I may just move the speaker to a small stand on the floor; there won't be any issues with the spouse/family . . . I built the damn room, I'll put my stuff in it where I see fit [​IMG]
    (yeah right)
    --
    - Jeff
     
  4. Phil_DC

    Phil_DC Stunt Coordinator

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    Someone on this forum told me about MoPads so I purchased a pair. http://www.warhogprod.com/en-us/dept_146.html
    Not only do they de-couple my center from my TV they also angle the center toward the listening area improving sound even more, I highly recommend them.[​IMG]
     
  5. Mike_Ch

    Mike_Ch Stunt Coordinator

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    I use feets under the centre and a fairly thick wool mat over the top of my tv. Felt would be just as good, it reduces the vibrations by a fair amount.

    Cheers,
    Mike
     

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