basement HT:concrete floors and subs

Discussion in 'Archived Threads 2001-2004' started by Joe Cole, Mar 18, 2002.

  1. Joe Cole

    Joe Cole Second Unit

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    After many a year in HT, I have reached the phase of wishing to build a dedicated HT in my basement. And I have a question about flooring.

    It is true, correct?, that concrete floors are not condusive to bass wave transmission? If this is true then a wooden floor would be good. My question is, if I wanted to save money would it work to put down wood only under my subs(3) two in the front and one in the rear corner? Since bass is very large waves would this work?

    Since my house is next to a major Interstate and at some point soon(within 5 years) the state will be buying my house to tear it down I don't want this room to be too fancy(i.e. money). I plan on just covering my two corner windows with wall board as an example. Probably will not finish the ceiling, just accoustic stuff in certain parts.
     
  2. Dave Poehlman

    Dave Poehlman Producer

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  3. Hugh Scrivener

    Hugh Scrivener Stunt Coordinator

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    QUOTE]This is why you see people investing in Bass Shakers and other tactile transducers and mounting them in their furniture and such... to regain that vibration lost with concrete[/quote]

    I've heard of these transducer things. Where can I check them out on-line?
     
  4. RAF

    RAF Lead Actor

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    Joe,

    I have a concrete floor in my HT (check out the construction pictures for full details) and I absolutely, positively have no problem feeling the bass. The sound waves from the subwoofers travel along the floor not through it.
     
  5. Jason Price

    Jason Price Second Unit

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    Robert,
    I'm very glad to hear you say that, as I'm in the process of building a theater (non-dedicated) in my basement, which is all concrete flooring. Your news is encouraging that my 20-39CS+ should still be able to shake my innards after I move it to the basement... [​IMG]
     
  6. Gregg Hart

    Gregg Hart Stunt Coordinator

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    I disagree completely. Cement floors absorb the bass very much in my opinion. I have a Velodyne 18" subwoofer that is difficult to feel due to my cement fllor. The thing is in the absolute correct place. I certainly feel it, but not as much as my 6-7 other friends with home theaters that all happen to have crawl spaces and hence a wooden floor. I have added 8 bass shakers to my main coach to add the feel I have lost. It makes a great addition and only cost me an extra few hundred for the shakers and an amp. If you are at all up for it, I suggest building a wooden floor in your basement to place everything on.

    Gregg
     
  7. Joe Cole

    Joe Cole Second Unit

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    Robert,

    You put the carpet right over the concrete? And you bass is fine? I have 3 subs, 2 SV 16-46 with new driver and a THX 18" Vel. Do you think this would be enough with concrete floors covered with carpet? 21x13 room with no ceiling just he floor from upstairs 8'5" to bottom and 7"9" to bottome of joyces(sp).

    I have been think of building a wooden floor with tongue and groove ply wood on 2x4s with vapor barriers and Pergo os something simalr on top of the ply wood. Any thoughts on this.
     
  8. RAF

    RAF Lead Actor

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    Well, I can only speak for myself and I'm telling you that my home theater, which has office grade carpeting installed directly over a 3-5" poured concrete floor provides me with all the bass that I need. (Friends have mentioned that it causes the hair on their arms to tingle.) Powerful, tight and loud where need be.
    My construction didn't allow me any real option to build a wood floor over a crawl space unless I wanted to sacrifice some ceiling space so I didn't even consider it. I'm not saying that if you A-B'ed a concrete floor compared to a floor over an open space that you might prefer the wooden floor because it didn't require as much effort for the lower frequencies to travel. Maybe it's a similar issue as found in different philosophies regarding speaker design.
    I would bow to those with more knowledge of the physics involved for a better explanation. I'm just saying that in my theater, with my construction, the amount of bass and the overall sensation has never ever been a concern.
    Note: I'm using an SVS 16-46PCi subwoofer and an M&K MX350 subwoofer in my installation.
    Upon re-reading the original posting in this thread I realize that the question can be interpreted at least two ways. On the one hand, Joe may have been asking whether or not concrete floors would be a hinderance to bass energy transmission. On the other hand (and the way I read it, although this might just have been me) he might have been wondering whether his enjoyment of subfrequencies would suffer with a concrete floor. While the presence of a sub-floor (no pun intended) might amplify the sub-frequencies and the "feeling," with any good subwoofers you can adjust them to give you a great vibrational experience regardless of the flooring. Only with weaker subs might the amplification of the energy be a help. My gut feeling is that sub-floors can introduce as many problems as they solve. For example, with my floor the sub can do its job and that's it. With various other understructures you might find it a bit harder for a sub to stop dead in its tracks because of some unwanted reverberation.
    Just my opinion, gang, not written in stone (concrete).
    [​IMG]
     
  9. Dave Bertrand

    Dave Bertrand Auditioning

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    Robert makes a good point. If you do build a subfloor, make certain you insulate between the sleepers with foam insulation board, or you may end up with resonant chambers.

    It is well known that a wooden subfloor will transmit tactile sensations better than a concrete one. Concrete does not absorb sound, it reflects it. But the bass energy from your subwoofer travels through the air also, so even with a concrete floor you'll still feel it vibrate the walls, your chair, and your body. It's just that you won't feel it AS MUCH as you would with a wood subfloor.

    I think concrete floors are uncomfortable even with carpet and pad. An insulated wood subfloor will keep your tootsies warmer, and be more comfortable to walk on or lay down on.

    By the way, a Pergo floor is a BAD idea in a theater. The last thing you want is floor reflections. Always use pad and carpet.
     
  10. Joe Cole

    Joe Cole Second Unit

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    Robert,

    I was or am wondering how concrete would effect my enjoyment of the low frequencies.

    I am not worried about the hardness, I can't sit on floors anyway. Hurts my joints too much. If I can find the carpet, it will probably save money also. I have wood floors now were my HT is. Reflections are no problem because I have enough accoustic foam to float a big boat, or at least cover one.

    Depending on the cost, I might go with the carpet. I do see that parquet is 1.30 a square ft. With a couple of throw rugs this might work.
     

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