HT bass trap, Bales or......?

Discussion in 'Home Theater Projects' started by GaryJ, Mar 31, 2005.

  1. GaryJ

    GaryJ Stunt Coordinator

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    Hi:

    I have a dedicated basement theater room that is 24’ wide and 32’ long. The room is fully draped by crushed velvet except for the screen which is 148” diagonal. The drapes are out 12” from the wall. There is an 18” steel beam that runs through the ceiling at about the mid point. There are three risers in the room holding 16 theater seats and there are two recliners in the front. There are 6 columns holding the surround speakers running ceiling to floor made from 25 Lb rigid polyurethane foam. I use an EQ to flatten the room out but without the EQ there are quite a few peaks and a couple of dips so the EQ and consequently the subs are working pretty hard. I have three subs so I have the headroom but would like to have the room flatter to begin with. Additionally I hope to add a little richness to the mid bass and later tame a little of the highs.

    I have the space in the corners to stack bales of fiberglass ceiling to floor and they would be out of sight behind the curtains. My question is, is this a good method or would I be better off building the 703 or 705 fiberglass panel traps or using the dedicated bass trap corner foam from someone like Auralex. It seems the cost would be pretty similar with any of the three options.

    Second, do you think I have to be concerned about the I-Beam running across the center of the ceiling?

    Third, my plan is to use 703 or 705 fiberglass panel traps at the first reflection points to the right and left and studio foam on the first reflection point on the ceiling.

    Thanks for your input.


    Gary
     
  2. Brad E

    Brad E Second Unit

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    The 703 on the first reflection points is a good idea and will be very effective.

    For bass traps, 703 does not work very well because it is far too thin to effectively reduce low frequencies.
    Bales of fiberglass will work much better.
    Although you could use bales of 703, which would work even better but at a much higher cost.
     
  3. GaryJ

    GaryJ Stunt Coordinator

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    Thanks for the input Brad.

    The 703 that I have seen comes in boards 2’X4’ not really in bales but I guess I could stack them and make them 8” or 10” thick. Would that work or would the cheaper bales of R-13 work better. Does it matter if the R-13 is paper backed since it is wound up in the Bale?

    My contact for the 703 said he can get some of the black sound attenuation board that they used to build the local IMAX. Any Idea how that might work?

    Thanks,

    Gary
     
  4. ChrisWiggles

    ChrisWiggles Producer

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    stuff like 703 or 705 is a lot denser than the fluffy stuff, just stack em thick, and out from the wall to improve bass absorbtion. Also shoot for corners rather than mid-wall to help for more bass absorption.

    Dunno what they use in imax, but just look at numbers, fiberboard is extremely effective, and cheap. Theres not much else that's that effective.
     
  5. PeterK

    PeterK Supporting Actor

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    Thats sounds like an awsome HT Gary [​IMG] You wouldn't happen to have pictures would you?
     
  6. GaryJ

    GaryJ Stunt Coordinator

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    Thanks Peter and Chris:

    I did an experiment and mounted four bales of R-13 in the top 4 tri-corners of the room. It did help tighten up the bass and I found I could actually listen without the EQ engaged. The room is still a little ragged with a peak at 34-35 HZ and and another good lift from 52-70HZ then a good dip for 90-110 Hz so the EQ is still needed. I am going to try the 703 panels in the corners and at a couple of other corners and see if I can smooth it out even further. With this experiment I am definitely becoming a believer in treating the room.

    I don't really have any pictures yet but I hope to soon. the room is close to being finished, at least the build out. I just have some steps for the risers and little finishes like that

    Thanks for your input.

    Gary
     

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