Trap that bass!!

Discussion in 'Archived Threads 2001-2004' started by PaulDF, Jan 14, 2003.

  1. PaulDF

    PaulDF Second Unit

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    As some of you may know, I am now getting ready to build some ASC Type tube traps for my room to tame the nastiness coming out of my EBS tempest. (You know what I mean).
    I have several questions after studying both Chris Tsutsui's, and Jon_Risch's Tube type traps.
    I was thinking of making 4 traps, 6 if two can be half-length.
    1. It looked like TWO layers of insulation were applied to the cage. The ends of each layer butted together and sealed as well as the sides. Is this right?
    2. After all insulation is on, It should be squeezed tightly with string or rope or wire, as tight as possible?
    3. When applying the second roll of wire mesh, it also should be pulled quite tight?
    4. Then snip the wires squeezing the insulation tight and pull it out, right?
    5. Are there advantages or disadvantages with rolling too tight or too loose?
    6. Finally a layer of cotton batting rolled around the trap twice or so. How is it held? Lots of tape or wire? Glue might actually work best.
    Burlap goen on here, hopefully find a neutral color.
    Now these traps looked to be about 4' tall and 17' in diameter.
    7. Would a 2' tall trap be effective as well? stackable? Could I place one under my rear surround tower and one on top? Would that be effective?
    8. What about objects in the direct path between the sub and the trap such as a couch, or small cabinet?
    9. Do the traps typically work best: suspended near the ceiling in a corner, midway down, or on the floor?
    10. What diameter of trap might be best for my room? It is 18*22' with a 7.5' ceiling. My sub is a 360L Tempest with an AVA 250 amp.
    I know there are a lot of questions asked here, sorry. But I want to have a pretty good handle on the situation, and also try to build something that will not stick out like a sore thumb(too much). If they really work, then its not so much a factor!
    All help appreciated, thanks guys. You've all been a great inspiration! (or is it peer pressure [​IMG] )
     
  2. ThomasW

    ThomasW Cinematographer

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    I guess the first question is have you measured (mapped) the room to see if bass traps are what you need?
    And have you tried alternate placements for the sub?
    Understand that I'm not saying that you don't need them, but no sense creating additional problems with a unknown cure.
    Also the diameter of the trap is dependent on the frequencies you want to absorb. The larger the diameter the lower the frequencies that are trapped.
    This link will get you started with some basic info. If you download a demo copy of ETF 5.0 it contains a section on calculating Helmholtz resonators
     
  3. PaulDF

    PaulDF Second Unit

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    I have measured my frequency response several times in my room, and with different sub placements.

    I have tried putting the sub in my listening position to find the best location to place the sub (location with the highest spl measurement anyway). Best was in the front right corner, exactly where I wanted it in the first place.

    So, after lots of advice from people on this forum, it is my understanding that bass traps are my next step in finding cleaner, more accurate bass in my room.

    I have a dip at 65hz and a peak at 83hz. 22db difference. Other than that there is just basically a 10db drop going from 100hz to 25, then starts to drop after 25hz. (not sure why when my rumble filter is set to 18hz, and my sub is tuned to 16hz??).

    I don't know how to better explain my room response, so don't hesitate to ask if you need more info.

    Paul
     
  4. Pete Mazz

    Pete Mazz Supporting Actor

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    Save yourself some time and just buy some bundles of fiberglass insulation. Put these in the corners of your room and have a listen. Then take TWs advice and find a way to really measure your room. ETF is a good program and will get you there. There are many ways to tame a room, and simply guessing what you need is not the most efficient way to go about it.

    A BFD may be in your future. Easier to tame the FR with one of these, especially if you like to experiment.

    Pete
     
  5. Ronnie Ferrell

    Ronnie Ferrell Second Unit

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    I second Pete's advise. That is exactly what I did. Go get 4 to 6 round bundles of 23" R-19 non-paper backed Owens Corning insulation at Lowe's or Home Depot.
    Owens Corning r-19 I used.
    [​IMG]
    Hand pick them. Some of the plastic will be ripped up on a lot of the packages. Its just insulation and Home Depot is not real careful with it. You don't want to get the stuff all over the house, itchy, itchy! Leave the insulation packaging on. You are soaking up pressure and the thin plastic will not hamper that much.
    Stack them in the corners of your room and see if they help. If so, keep the insulation and proceed with the tube traps. Make them 46" tall and use 2 cut pieces 23" wide of the R-19 for each trap. If it does not help take the R-19 back for a refund.
    Even if you keep the insulation, you will probably only need one roll of it for the traps. I made four 4-feet tall by 14" diameter traps with one 23" by 93" (I think it was 93") roll of the stuff.
    Ronnie
     
  6. PaulDF

    PaulDF Second Unit

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    Geez, I am running in circles here. First I wondered if I made the right decision after I built my EBS. Then I decided bass traps might help. Then I considered the BFD instead, then both... Then back to the traps. Now I just don't know what I'm doing anymore, and its getting less fun all the time!!

    ThomasW: Wow, a lot of info at that site. Thanks. I am thinking a lot of that might be too technical for me, and my humble sound system may not be worthy of that much technology and effort. I will keep at it though. I simply wanted to soak up as much reflection below 150 or so hz that I could.

    Pete and Ronnie: Thats a great idea, plain old bundled up insulation... Is it effective enough to be easily noticable? I will try it as soon as I can, Thanks!

    Paul
     
  7. Pete Mazz

    Pete Mazz Supporting Actor

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  8. Ronnie Ferrell

    Ronnie Ferrell Second Unit

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  9. My bass traps are along the lines of Helmholz resonators. They are very vary simple. a pair of 10" ID concrete forms with an 11" disk as a base. The other end is completely open. I have about 3" of sand to lower the center of mass. The net length inside is about 53 or 56" iirc (i fogret without measuring) which tunes them to ~63hz. I also used 1" fiberglass (that the insulate pipes with....semi rigid) for HF reflections all around.

    The result. about 2db of FR loss at the desired frequency band. Nothing much. BUT, a noticable amount of ringing is gone! This means I can then EQ out the peak easier and won't have as much ringing artifacts.
     
  10. PaulDF

    PaulDF Second Unit

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    I don't know if I have much ringing in my room, but you never know. A buddy of mine has some leftover bags of insulation, so I'll borrow them and put them in my room. He thinks I'm nuts. Maybe I am.

    But at least my curiosity will be satisfied.

    Thanks guys.
     
  11. Ronnie Ferrell

    Ronnie Ferrell Second Unit

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  12. PaulDF

    PaulDF Second Unit

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    Just a followup...

    Okay, finally I got around to really experimenting with some down and dirty traps. I have 5 big bags of insulation and have tried them all over my room. Mostly in the three corners I have and along the rear wall.

    When measuring FR, the change is minimal. 2 to 3 db. So as a means to flatten my response, the traps barely help at all.

    When listening to assorted music, I honestly can't hear any difference. If it was a blind test, I'd never be able to hear a difference. I had thought that placing a bag behind each main front speaker improved the clarity of the sound a bit, and added more treble, but after many swaps found that there was very minimal change.

    I never did have much echo or ringing problems in my room. If I had, maybe the traps would've helped more. If I want to flatten my response, I think equalization is the only way.

    Thanks to all who offered their advice and for links to room treatments.

    Paul
     

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