SVS Subs in Rooms with Concrete Floors?

Discussion in 'Archived Threads 2001-2004' started by GrahamO, Feb 6, 2002.

  1. GrahamO

    GrahamO Auditioning

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    I am currently in the construction phase for my dedicated home theater in my basement. As I live in the Midwest, the basement floor is concrete as are three of the four walls. Based upon the outstanding reviews on the various home theater sites, I had decided to purchase either a SVS 30-39CS or 25-31CS. I listen to 75% movies and 25% music and the SVS seemed the best option to give me high output with control.

    That is until I read the excellent "Need help with 20-39CS" thread started by Conrad S. After an exhaustive and incredibly informative process of elimination, the culprit behind the poor performance of his SVS was attributed to room acoustics. Specifically, the concrete floor of his room was noted as an issue. I was extremely surprised to find that such a well reviewed sub would fair poorly in what I feel is not that abnormal of a room construction.

    What I need help on is some perspective if the SVS subs truly have issues with concrete floors and walls? Is this mainly due to the down-firing nature of the sub and its interaction with the concrete floor? Are the other concrete floor success stories out there with SVS?

    As a note, my second and third choices were the Hsu VTF-2 (also down-firing - same problem?) and the Paradigm 2200. Thanks for the help.
     
  2. Nick P

    Nick P Second Unit

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    GrahamO,

    I read through that thread and was as befuddled as everyone else. Let me assure you though, my twin SVS setup has no problems in my room with carpeted concrete floors. I have incredible SPL and physical impact. Something very strange was happening in Conrad's room. That's for sure.
     
  3. Shawn Sefranek

    Shawn Sefranek Second Unit

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    No problems with my twin SVS plus's on a concrete floor.
    Read my full review: HERE
    Shawn S
     
  4. Bhagi Katbamna

    Bhagi Katbamna Supporting Actor

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    No problems due to concrete floor in my 7000+ cu. ft room.
     
  5. Paul Clarke

    Paul Clarke Supporting Actor

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    There should be no problem. My HT room is on a thickly carpeted concrete slab and my sub downfires onto a piece of colorful granite from the local building supply.
     
  6. JohnRice

    JohnRice Lead Actor

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    The only drawback to a concrete floor is that it doesn't vibrate, but that will be the case using any sub. I assure you, the SVS will do a fine job.
     
  7. Ron Shaw

    Ron Shaw Stunt Coordinator

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    Concrete is better than a crawlspace (or stud walls), because you dont loose acoustical energy through them. This isnt to say they will be better acoustically, which is a function of many variables, but I find walls and floors that are not 'flexable' to be prefered over those that are. If you have problems with acoustics, the next most likely culprit will be standing wave nodes that are a function of room dimensions.
     
  8. James Edward

    James Edward Supporting Actor

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    I must disagree with Ron. Every setup I have done or listened to had MUCH more bass energy in a suspended wood floor( crawlspace, or over a basement) environment. A stronger sub is always needed in concrete floor situations in my experience. It's not the response itself, it is the transmission through the floorboards that makes the perception that much greater.

    I am always amazed at how well some smaller subs (NHT SuperSub, JBL PB12, Velodyne 810, Velodyne CT 100) perform in larger rooms with wood floors vs. my 12x12 concrete. I use an SVS 20-39PC and it rocks my room. Then I brought it to another home with a suspended wood floor, and it was downright scary.

    Big Caveat: All of these observations pertain to HT, NOT music. Maybe a 'tighter' sound is desirable for music.

    I NEED the SVS in my room. Smaller subs just don't cut it. But they DO cut it with suspended floors. But the SVS cuts it, dices it, blends it and cooks it!
     
  9. Nick P

    Nick P Second Unit

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    Ron and James...I think you are both right but in different ways. A traditional "suspended" type wood floor will give you more tactile sensation but the solid concrete floor will not absorb any energy and perhaps give more air movement. Coming from a bicycling background I can tell you a rigid frame will conduct more power to your forward thrust. A flexible frame absorbs much of your energy and it never gets applied to your movement. It makes sense to me that the same could apply to sound waves.
     
  10. Ron Shaw

    Ron Shaw Stunt Coordinator

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    I agree. A wood floor will certainly let you feel it, but measuring frequency response will show less energy is being transmitted through the air. It is possible that if your walls are flexible enough, they can redistribute energy into the room (sorta like a passive radiator), but accuracy will suffer. You will notice that in the design and construction of recording studios, dubbing stages, theaters and sound stages, they go to great lengths to make the boundries rigid. A typical sound stage floor consists of a base of concrete, asphalt with embedded rail road ties, covered with hardwood.

    James mentioned how much better subwoofers perform in larger rooms vs. his 12x12 concrete. I bet they do, but more from the larger space than the floor boards. To really develope any given wavelength, you need room dimensions at least equal to the wavelength. For a 20 Hz note thats over 50 feet! Few of us have rooms that size, so most of us listen to music in 'compression' mode, like headphones, which doesnt really sound like the real thing. When you go to a concert, you notice the bass actually cuts through your body, even though SPLs are no higher (and maybe less) than the SPLs you use at home. This is because of the wavelength developement. Larger rooms do sound better!
     
  11. JohnRice

    JohnRice Lead Actor

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  12. James Edward

    James Edward Supporting Actor

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    I guess the bottom line for me is: cement floor= need for overkill in the bass department.
     

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