Internal Vibrations

Early B.
Early B. Posts: 7,900
edited December 2005 in Subwoofer Hookup & Bass Management
How do you determine if your sub is not properly braced or could benefit from improved bracing?

Is there a way to measure or determine the amount of bracing needed in a sub?

Thanks.
HT/2-channel Rig: Sony 50” LCD TV; Toshiba HD-A2 DVD player; Emotiva LMC-1 pre/pro; Rogue Audio M-120 monoblocks (modded); Placette RVC; Emotiva LPA-1 amp; Bada HD-22 tube CDP (modded); VMPS Tower II SE (fronts); DIY Clearwave Dynamic 4CC (center); Wharfedale Opus Tri-Surrounds (rear); and VMPS 215 sub

"God grooves with tubes."
Post edited by Early B. on
· Share on FacebookShare on Twitter

Comments

  • PolkThug
    PolkThug Posts: 7,532
    edited December 2005
    See if it sounds better with a heavy weight on it.

    Measure decay.
    Never Forget
    · Share on FacebookShare on Twitter
  • tryrrthg
    tryrrthg Posts: 1,896
    edited December 2005
    There is some sort of test equipment out there that will measure the movement of cabinet walls, but I don't remember off hand what it is called. I'm sure it's not that cheap.

    According to all the DIY gurus this is the proper way to build and brace a sub with a high excursion 15" driver.

    Some of it is probalby overkill for most real world applications but it all depends on how crazy you want to get. If you don't want to mess with bracing at all build a sonosub.
    Sony KDL-40V2500 HDTV, Rotel RSX-1067 Receiver, Sony BDP-S550 Blu-ray, Slim Devices Squeezebox, Polk RTi6, CSi3 & R15, DIY sub with Atlas 15
    · Share on FacebookShare on Twitter
  • Early B.
    Early B. Posts: 7,900
    edited December 2005
    tryrrthg -- that link you provided is defintely overkill for bracing. It would be cost prohibitive, take a lot more time to build, and the sub would be very, very heavy. Not sure how much SQ difference it would make anyways.
    HT/2-channel Rig: Sony 50” LCD TV; Toshiba HD-A2 DVD player; Emotiva LMC-1 pre/pro; Rogue Audio M-120 monoblocks (modded); Placette RVC; Emotiva LPA-1 amp; Bada HD-22 tube CDP (modded); VMPS Tower II SE (fronts); DIY Clearwave Dynamic 4CC (center); Wharfedale Opus Tri-Surrounds (rear); and VMPS 215 sub

    "God grooves with tubes."
    · Share on FacebookShare on Twitter
  • tryrrthg
    tryrrthg Posts: 1,896
    edited December 2005
    Early B. wrote:
    tryrrthg -- that link you provided is defintely overkill for bracing. It would be cost prohibitive, take a lot more time to build, and the sub would be very, very heavy. Not sure how much SQ difference it would make anyways.
    You're probably right, but that's the beauty of DIY, YOU get to decide if it's overkill or not, not some executive trying to cut corners/costs.

    Personally I don't think it's that much overkill, large panels in a sub like that (some are around 3 feet in length) will certainly vibrate like crazy, causing nasty resonances. If I had a dedicated theater room I'd certainly go to that degree of "overkill" but a box that big just won't fly in the REAL world.
    Sony KDL-40V2500 HDTV, Rotel RSX-1067 Receiver, Sony BDP-S550 Blu-ray, Slim Devices Squeezebox, Polk RTi6, CSi3 & R15, DIY sub with Atlas 15
    · Share on FacebookShare on Twitter
  • MacLeod
    MacLeod Posts: 14,358
    edited December 2005
    Im assuming youre going to build your own box? How many watts are you going to be pushing?

    Im running about 400 to my sub and built the box out of 1/2" birch plywood and have no issues with flexing.

    Unless youre going to be running near 1000 watts, I would worry too much about bracing. Just make sure the enclosure is well sealed and built properly and it should be rigid enough.
    polkaudio sound quality competitor since 2005
    MECA SQ Rookie of the Year 06 ~ MECA State Champ 06,07,08,11 ~ MECA World Finals 2nd place 06,07,08,09
    08 Car Audio Nationals 1st ~ 07 N Georgia Nationals 1st ~ 06 Carl Casper Nationals 1st ~ USACi 05 Southeast AutumnFest 1st

    polkaudio SR6500 --- polkaudio MM1040 x2 -- Pioneer P99 -- Rockford Fosgate P1000X5D
    · Share on FacebookShare on Twitter
  • VR3
    VR3 Posts: 28,646
    edited December 2005
    I believe in absolute overkill..

    I kind of feel I didnt put enough bracing in my main channel rebuilds I am working on... that 10" or so of empty space is bugging me... I may have to add a few strips... lol...

    But 230" of bracing...is cool!

    ASBP10Bbracingpic1Ver2.jpg

    One of the EASIEST ways to tell if your box is braced, that takes like 1 second is knock on it...

    If your box dosnt go... THUD.. something is wrong or it isnt braced enough. There should be barely any resonance...

    Why build something thats supposed to be better than the competition (for the same money) and not go all the way. Yall regret it in the end.

    I used strips and plywood for a few reasons BTW-
    It dosnt take up as much air volume... and plywood is stronger and lighter weight... FWIW
    - Not Tom ::::::: Any system can play Diana Krall. Only the best can play Limp Bizkit.
    · Share on FacebookShare on Twitter
  • goingganzo
    goingganzo Posts: 2,793
    edited December 2005
    i have some isued with vibration. the whole wall with i installed my ib shakes. befor i re enforced it with a 2x6 it would move 1/8 of an inch. i will be adding more braces later when i get time now it just shakes the entire house.
    · Share on FacebookShare on Twitter
  • Dennis Gardner
    Dennis Gardner Posts: 4,861
    edited December 2005
    Depends on the design somewhat. Ported boxes such as the linked one don't need as much since pressures are lower. You need enough to keep long spans from flexing and break up the panel vibes. Sealed boxes need alot more attention to panel flex though.

    I have always liked the cross type bracing on the Adire designs.
    HT Optoma HD25 LV on 80" DIY Screen, Anthem MRX 300 Receiver, Pioneer Elite BDP 51FD Polk CS350LS, Polk SDA1C, Polk FX300, Polk RT55, Dual EBS Adire Shiva 320watt tuned to 17hz, ICs-DIY Twisted Prs, Speaker-Raymond Cable

    2 Channel Thorens TD 318 Grado ZF1, SACD/CD Marantz 8260, Soundstream/Krell DAC1, Audio Mirror PP1, Odyssey Stratos, ADS L-1290, ICs-DIY Twisted , Speaker-Raymond Cable
    · Share on FacebookShare on Twitter