Bass trap plan...worth doing?

Discussion in 'Speakers & Subwoofers' started by PaulDA, Jul 30, 2005.

  1. PaulDA

    PaulDA Cinematographer

    Joined:
    Feb 9, 2004
    Messages:
    2,699
    Likes Received:
    97
    Trophy Points:
    4,110
    Location:
    St. Hubert, Quebec, Canada
    Real Name:
    Paul
    I have a room that is 10x22, that, while not a perfect rectangle, is pretty close. I have acoustic drop ceiling tiles (already there when I moved in--5/8" thick made of fibreglass--the yellow stuff like the Owens 703, just thinner). The "rear" of the room (behind the listener) is curtained off (I have to use 10x7 of the room for storage and I did not want to build a wall). The storage area is quite full of various boxes, shelves and whatnot, so bass traps in there are impractical at this time (perhaps in a year or two). This leaves me with a 10x15 space with which to work. I've plotted my FR with the BFD spreadsheet and RS SPL analogue meter. (I have no idea how to post an image but the response is flat from 25 to 40, rises gently by 5 dB from 20 to 25, drops by 13.5 dB from 40 to 50, rises by 3.5 dB from 50 to 56, dips by 9 dB from 56 to 63, rises by an equal amount to 71, is flat to 89, rises gently by 6 dB to 111, dips by 7 dB to 125 and rises back to flat (+/- 1.5 dB) to 160 (relative to the 71 to 89 stretch).

    2076.5
    22 80.5
    2584.0
    2884.5
    31.584.5
    3685.0
    4085.5
    4580.5
    5071.5
    5675.0
    6366.0
    7175.0
    8076.5
    8975.5
    10079.5
    11181.0
    12572.5
    142.575.5
    16074.5

    The first column is the frequencies, the second the (corrected) dBs. This was plotted from the listening position using the sub and the mains, crossed at 80hz (I tried 60, 100, 120 and 150, but 80 was the flattest). After many hours of plotting and moving the sub, this was as flat as I could get the curve.

    I cannot place standard corner traps up front (behind the sub and mains) because of space constraints. I had thought to make my own "half" corner trap for the corner farthest from the sub (my right, from the listening position) by getting a box of the acoustic ceiling panels and stacking them/cutting them to fit. I can place a trap in that corner about 3 feet high and 4 inches thick. The other corner is not usable as it holds some of my gear (no way around that for awhile). I thought to make my own version of the ASC Subtrap by placing a stack of 2x2 of the ceiling tiles, about 18" thick, sandwiched between two pieces of MDF (say 1/2 or 3/4 of an inch thick) wrapped in cloth. Would that act as a bass trap well enough to partially compensate for the lack of a corner one, or is it just a waste of time?

    Sorry about the length of my post, but without pictures, I needed to describe it as best as I can.
     
  2. ChrisWiggles

    ChrisWiggles Producer

    Joined:
    Aug 19, 2002
    Messages:
    4,791
    Likes Received:
    1
    Trophy Points:
    0
    Bass traps are almost always a good idea. The best way is fiberboard straddling a corner, very simple, cheap and effective.
     
  3. PaulDA

    PaulDA Cinematographer

    Joined:
    Feb 9, 2004
    Messages:
    2,699
    Likes Received:
    97
    Trophy Points:
    4,110
    Location:
    St. Hubert, Quebec, Canada
    Real Name:
    Paul
    That's my plan for the right hand corner (I can get the ceiling tiles--made from fibreboard--very cheap at my local home renovation store). The left hand corner is not available, so that's why I thought I'd try a "home-made" version of the ASC SubTrap that Ed Mullen reviewed favourably over at Secrets. I might even buy one, but the cost seems high (after conversion and shipping to Canada) whereas I can make one for a lot less (even if it's not as good). I was hoping someone could tell me if the "home-made" platform for my sub would be effective enough as a trap to be worth the effort.
     
  4. Mike Keith

    Mike Keith Second Unit

    Joined:
    Jan 24, 2002
    Messages:
    324
    Likes Received:
    0
    Trophy Points:
    0
    Tube style traps don't do a lot of good according to my research, you need a lot of surface coverage with a broad-band absorber to do some real good. Panel traps covering corners and wall celing junctions, many of them.
     
  5. Wayne A. Pflughaupt

    Moderator

    Joined:
    Aug 5, 1999
    Messages:
    6,207
    Likes Received:
    55
    Trophy Points:
    9,110
    Location:
    Katy, TX
    Real Name:
    Wayne
    Paul,
    Perhaps someone better versed in bass traps than I am can weigh in, but it sounds to me like you’ve ruled out just about every good location. I don’t think you’ll have much success using them in only one location.

    You might try a parametric equalizer as an alternative. They’re usually very effective and way cheaper than traps.

    Regards,
    Wayne A. Pflughaupt
     

Share This Page