How to make my tempest better

Discussion in 'Archived Threads 2001-2004' started by Nathan J, Mar 24, 2003.

  1. Nathan J

    Nathan J Stunt Coordinator

    Joined:
    Mar 24, 2002
    Messages:
    234
    Likes Received:
    0
    Well, recently I finished my DIY tempest with a 250 watt plate amp. Right now it is just rough MDF, but as soon as some decent weather hits, I am going to be covering it with some nice wood and staining it.

    Anyway, as of yet, I have not added any sound damping material to the inside,or polyfill, or anything like that.
    Is there anything that I can do to increase sq or spl, or just plain old make it sound better?





    -Nate
     
  2. ThomasW

    ThomasW Cinematographer

    Joined:
    Nov 6, 1999
    Messages:
    2,282
    Likes Received:
    0
    If it's a sealed box 'stuff' it with fluffed polyfill at a rate of 0.5-1.5 lbs/cu ft. Experiment for the sound you like best.

    If it's a ported box, line the interior surfaces with a couple of inches of poly or fiberglass insulation. Keep it away from the port opening.

    Nothing other than using more drivers or a bigger amp will increase the actual output (SPL)
     
  3. Owen Bartley

    Owen Bartley Second Unit

    Joined:
    Nov 11, 2002
    Messages:
    487
    Likes Received:
    0
    If its ported, definetely don't stuff it. For some reason I was under the impression that you still should, so I did that first. It still sounded good, but when I corrected this and pulled the stuffing out and then lined the walls with eggcrate foam over a layer of polyfill, it sounded much better. You can see pics of both attempts on my page.
     
  4. Mike Strassburg

    Mike Strassburg Second Unit

    Joined:
    Nov 4, 2001
    Messages:
    421
    Likes Received:
    0
    Pick up another Tempest/amp and build a second enclosure or one BIG one......problem solved!!
     
  5. TimForman

    TimForman Supporting Actor

    Joined:
    Dec 4, 2002
    Messages:
    847
    Likes Received:
    0
    I was happy with my sealed MidQ Tempest then I added a Shiva 'tube to the back of the room. Now I'm ecstatic. It improved the spacial quality of the lower tones along with solid impact from movies. My HT
     
  6. Allen Ross

    Allen Ross Supporting Actor

    Joined:
    Sep 30, 2002
    Messages:
    819
    Likes Received:
    0
    oh man, i stuffed my 9 cu-ft box with 5 lbs of lose poly fill, so you are saying that i should take it out and replace it with just egg crates? or can i spray it with adhesive and stick it to the walls?
     
  7. Nathan J

    Nathan J Stunt Coordinator

    Joined:
    Mar 24, 2002
    Messages:
    234
    Likes Received:
    0
    Oh, yea, I forgot to mention that it was a ported box.....after bracing the internal volume is about 7.8 cubes. I have it tuned to 20-21hz, and I am using two 4" ports. I like the eggcrate Idea....probably less chance of that coming apart and getting stuck in the ports or something. What about spray on sound deadener? Something that comes in those cans? I see that PE had a special on that stuff about a week ago. Has anyone ever tried it? Did it make a difference?

    Either way, I think the eggcrate foam is the cheapest, and easiest way, so thats probably what I will end up doing.


    Thanks,
    Nate
     
  8. Lee Carbray

    Lee Carbray Second Unit

    Joined:
    Oct 23, 2002
    Messages:
    308
    Likes Received:
    0
     
  9. Owen Bartley

    Owen Bartley Second Unit

    Joined:
    Nov 11, 2002
    Messages:
    487
    Likes Received:
    0
    Allen: I think if I were you I would try to stick the polyfill to the sides of your enclosure (glue... staples?). I used the foam becaue I had some lying around, and I just stapled it on over a layer of polyfill. I think you can get away with just the polyfill pretty easily. The big problem in mine was that the stuffing really impeded airflow and I ended up with a quieter sub. But now it plays louder, and it seems to not distort as easily.

    Nathan: the foam was really easy, like I said, I just threw some polyfill on the back of it and stapled it to the inner walls after I cut the panels to size. I think I've heard of people using sound deadener spray, but I can't remember the results... it seems like it would cut down on some of the box resonance and help a bit... I don't think it couls hurt. If I hadn't gone over budget on the paint it was something I was thinking about trying on mine.
     
  10. BrianJ>Y

    BrianJ>Y Stunt Coordinator

    Joined:
    Jan 2, 2003
    Messages:
    99
    Likes Received:
    0
    About those spray on sound dampeners...does anybody know if there's a difference between what PE sells and the rubber automotive sprays that you can buy at pepboys for half the cost? Ron Stimpson used these "rubberized undercoating" sprays from pepboys on his DIY sub project page. Wondering if the stuff PE sells is worth the extra, i'm thinking there isnt a difference though?
     
  11. Nathan J

    Nathan J Stunt Coordinator

    Joined:
    Mar 24, 2002
    Messages:
    234
    Likes Received:
    0
    Well, I am not sure if there is a big difference or not. I know that Pruducts like Stinger Roadkill and Raamat products are specifically designed for audio use. As to whether they are any different from the rubberized undercoating...I am not sure. I would think they they might be a little easier to work with....perhaps not quite so messy, but I dont have that much experience with them.
    Be careful with some of those other brands though......som of them do not "dry".....like they stay almost tar-like forever, and are a pain to get off, Whereas some of the other brands actually dry to form a rubber coating.
     
  12. ThomasW

    ThomasW Cinematographer

    Joined:
    Nov 6, 1999
    Messages:
    2,282
    Likes Received:
    0
    Using a sound damping coating does nothing but add mass (weight) to the enclosure, this will slightly lower the Fs of the cabinet.

    Save your time/money.....
     
  13. Frank Carter

    Frank Carter Screenwriter

    Joined:
    Mar 12, 2002
    Messages:
    1,187
    Likes Received:
    0
    When I was into car audio, I used used the auto rubberized undercoating to dampen my car doors. It worked superbly, I doubt I would have seen a difference with buying something like the Stinger Roadkill. I plan on using it again no some sonotsubs I'm gonna do for my HT.

    I do remember it made a hell of a mess. Luckily I was prepared before hand with newspaper and masking tape.
     
  14. Chris Tsutsui

    Chris Tsutsui Screenwriter

    Joined:
    Feb 1, 2002
    Messages:
    1,865
    Likes Received:
    0
    I agree with ThomasW [​IMG]

    Don't put a vibration dampener coating on the inside of the sub although it does add mass and reduce vibrations. (which is generally a good thing)

    To be honest, I couldn't tell the difference when I added/removed 4lbs of polyfil to my adire alignment tempest.

    I wouldn't get egg crate for a sub since the egg crate has barely any ability to absorb the subwoofer's frequencies. If you use polyfil, just shove it in there and try not to obstruct the ports and driver.
     
  15. Aaron_Smith

    Aaron_Smith Stunt Coordinator

    Joined:
    Jul 22, 2002
    Messages:
    105
    Likes Received:
    0
    The purpose of a vented enclosure is to act as a resonator to control the motion of the bass driver. Any damping material you add to the enclosure can reduce the box's effectiveness as a resonator. The purpose for adding it to a full-range speaker is to control mid-range radiation from the back of the driver from leaving the port; however, since a sub is not going to reproduce midrange frequencies, this is unimportant.
     
  16. ThomasW

    ThomasW Cinematographer

    Joined:
    Nov 6, 1999
    Messages:
    2,282
    Likes Received:
    0
    During 25yrs of sub building, I've yet to hear a box sub that didn't benefit from the correct addition of damping materials such as poly/fiberglass.

    Subs end up 'playing' some upper midbass/midrange info because of the roll-off of the XO slopes. Use of damping materials helps absorb those frequencies.

    Proper choice and installation of the damping material will not have a negative inpact on port performance. The port is operating at frequencies well below those that a reasonable layer of damping will impact. If the damping is physically blocking the air flow to the port, then of course there will be problems.

    Note that eggcrate/acoustical foam must be VERY VERY thick (6"-12") to actually absorb LFE. So using a couple inches to line the interior of a sub will only impact the higher frequencies coming from the driver.

    Frank C.

    There will be absolutely no audible benefit to applying a spray-on material in a tube sub. Mass loading the sub is completely unnecessary given the relatively inert physical properties of the paper used for the tube.

    People need to understand that these coatings in and of themselves absorb nothing. They simply add mass = dampen what they are applied to. They of course make a big difference in the Fs when applied to bare metal/thin plastic. But no one I know is making subs out of these materials.
     
  17. PaulDF

    PaulDF Second Unit

    Joined:
    May 17, 2002
    Messages:
    354
    Likes Received:
    0
    I used spray on sound deadener in my box sub, and a layer of batting on top of that. I can't comment on the effectiveness because this is my one and only DIY sub, and I'm not tearing the stuff out.

    What I can say is this - As Nathan said, make SURE you use a spray that hardens within a reasonable time. I used (I think it was) "Bondo" spray from walmart, and it just never dried hard. Now quite often when I crank up some tunes I can smell that crap because the sub is breathing so heavily. I think its getting better, but I'll never use that stuff again!!
     
  18. Allen Ross

    Allen Ross Supporting Actor

    Joined:
    Sep 30, 2002
    Messages:
    819
    Likes Received:
    0
    bummer, i smelt acidic acid (viniger) for about a week after building my sub while the silicon i sealed it with dried. When i applied it i could barly breath it was so strong
     

Share This Page