Slab Floor Problem

Discussion in 'Home Theater Projects' started by Torgny Nilsson, May 30, 2003.

  1. Torgny Nilsson

    Torgny Nilsson Second Unit

    Joined:
    Jan 8, 2003
    Messages:
    255
    Likes Received:
    1
    Trophy Points:
    0
    I am planning to build a home theater in a room that has a concrete slab floor, which sucks most of the impact out of my subwoofer. I thought about building a wood super-floor above the slab floor, but cost is a concern and the ceilings are only 8 feet high to begin with. Has anyone dealt with this problem?
     
  2. Darren Mortensen

    Darren Mortensen Stunt Coordinator

    Joined:
    Jul 26, 2001
    Messages:
    232
    Likes Received:
    0
    Trophy Points:
    0
    Torgny,

    Many of us have built on slab floors, including myself. There are several methods of correction for audio LFE deflection and absorption. I currently use a Velodyne 12" subwoofer, which is grossly underpowered at 100w for the size of my cinema.

    What I notice is that the bass LFE can be heard...but not felt..meaning that the sub bottoms out before you get that chest vibrating sensation from the big action on the screen.

    I am upgrading to a new SVS subwoofer soon to help correct this...however an alternative is tactile simulators: ButtKickers, Bass Shakers, etc....can do the trick. As an experiment I installed a pair of Aura Pro Bass Shakers, one each, into two of my cinema recliners for about $80.00 and connected them to an old receiver to act as the power amp. The result was simply amazing.

    For the first time I got bass results I was hungry for. With the shakers placed just below seat cushion and bolted to the chair frame, the chair would rumble with the explosive on-screen action!

    To go further, I had a friend from work visit my cinema...this is a guy who has owned some very VERY high end stereo equipment and is just getting into HT.

    I played the first five minutes of Resident Evil for him with the tactile sensors on. He was astonished! He couldn't get over the fact the Velodyne subwoofer was so powerful and precise. I surprised him when I told him I had the Velodyne shut off the entire presentation!!!

    Then I repeated the presentation switching from the Velodyne Subwoofer on..then off...then with the shakers....and then without. I explained the shakers also helped with my marriage...as when I want to watch a movie when the wife is asleep, I can turn the sub off and let the shakers do the work..and my wife doesn't hear or feel a thing!
     
  3. Torgny Nilsson

    Torgny Nilsson Second Unit

    Joined:
    Jan 8, 2003
    Messages:
    255
    Likes Received:
    1
    Trophy Points:
    0
    Thanks for the information on the Bass Shakers. They sound like one possible solution, but I don't plan on buying dedicated theater seats or screwing bass shakers to the sofa.

    Does anyone out there have a solution that would allow everyone in the room to feel as well as hear the bass, regardless of what chair they are in? Would a small elevated base, under the sub and connected to the wall, do any good as far as feeling the bass?

    I have an SVS sub which I could really feel in my last house, but can't feel in my new house(though I can still hear it).
     
  4. Mark McGill

    Mark McGill Stunt Coordinator

    Joined:
    Feb 20, 2002
    Messages:
    83
    Likes Received:
    0
    Trophy Points:
    0
    My theatre is on a slab floor and the cure is a second sub. I've got one SVS in the front and a second tuned down to 16hz in the back. The freaking couch vibrates.

    The reason I got the second SVS is becuase of my room shape. I thought the single sub was great but just wanted a little more. Good luck.
     
  5. Dave Poehlman

    Dave Poehlman Producer

    Joined:
    Mar 8, 2000
    Messages:
    3,813
    Likes Received:
    0
    Trophy Points:
    0
     
  6. Torgny Nilsson

    Torgny Nilsson Second Unit

    Joined:
    Jan 8, 2003
    Messages:
    255
    Likes Received:
    1
    Trophy Points:
    0
    I would love to build an floor over the slab, but because of design limitations and cost, I don't think that is an option.

    Does anyone think it would work to build a small 2 by 2 foot floor directly under the subwoofer, and to attach that to one of the walls so that the vibrations are transmitted to the walls? I don't know if that would transmit any vibrations to the people sitting in the room though. Probably a crazy idea.

    So how to bass shakers work? Does the sub signal get split and get sent to the sub and to the shakers? What's the point of having a goos sub if you have shakers?

    I am pretty new to the whole sub thing, only having had one for about 6 months, so this is all new to me.
     
  7. JustinG

    JustinG Stunt Coordinator

    Joined:
    May 21, 2003
    Messages:
    114
    Likes Received:
    0
    Trophy Points:
    0
    Actually, Torgny, I was thinking along the same lines as you. Build a small riser like 2'x2' under the sub. You could carpet or paint it to match your interior. Though, you would want to put some layer of material between the riser and the slab to eleminate any vibration the riser might have on the slab. Maybe a rubber or foam door seal gasket.

    Also, as an idea, would putting some industrial carpet down (the kind you find in office buildings) help at all? Aesthetically, I would think so, but aurally, I don't know if it would help.
     
  8. JohnGil

    JohnGil Stunt Coordinator

    Joined:
    May 14, 2003
    Messages:
    65
    Likes Received:
    0
    Trophy Points:
    0
    The sub is not designed to shake the room it is meant to play low frequency information. If you don't want to use s shakers and are more concerned with boom I suggest getting more than 1 sub maybe 2 or 3 is an option. Also, even if you are able to transfer the vibration to the wall, how would the vibration transfer to your seating position?

    With bass shakers you use the subwoofer output from your receiver or AV pre-amp with a Y connector to the shaker amp and then speaker wires to the shakers. Before you write them off as well as the effect do a search for tactical transducers here and on the web and read more about them. If possible, also go to a store that sells them or has them set up in there listening room and check out the effects for yourself. I think you will be happily amazed by the results.
     
  9. Dave Poehlman

    Dave Poehlman Producer

    Joined:
    Mar 8, 2000
    Messages:
    3,813
    Likes Received:
    0
    Trophy Points:
    0
    Bass shakers are basically just speakers that make no noise... only vibration.
     
  10. Torgny Nilsson

    Torgny Nilsson Second Unit

    Joined:
    Jan 8, 2003
    Messages:
    255
    Likes Received:
    1
    Trophy Points:
    0
    Thanks for the continued input. I have heard good things about shakers, but don't have any good way to run cables to the furniture that won't be tripped over (the slab floor problem again).

    I had the same concerns about a riser: that it would transfer the vibrations to the wall, but not to the seats that are out on the slab floor.

    I have to admit that my SVS sub SOUNDS great even with a slab floor. But I do miss the physical rumble I got in my old house when playing a movie. I get the impression that my two choices are a super-floor above the slab floor, or bass shakers with cables across the top of the slab floor.

    Thanks again for the info.
     

Share This Page