Vibration from thr cab!!??

Discussion in 'Amps and Cabs [BG]' started by Jd261808, Mar 21, 2011.


  1. Jd261808

    Jd261808

    Apr 18, 2010
    I have a 2x15 bass cab and when I play it vibrates like crazy. It almost sounds like the one speaker is blown. But they are brand new. Also, when I take the back off, the vibration is gone when I play. What can I do to get rid of this terrible noise? Any suggestions? So when the back is off it sounds fine and when the back is on it's vibration is bad. What you think?
     
  2. billfitzmaurice

    billfitzmaurice Commercial User

    Sep 15, 2004
    New Hampshire
    Owner, Bill Fitzmaurice Loudspeaker Design
    I think your cab lacks bracing. Do not play with the back off, blown drivers can result.
     
  3. JimmyM

    JimmyM

    Apr 11, 2005
    Apopka, FL
    Endorsing: Yamaha, Ampeg, Line 6, EMG
    what kind of cab is this that has a removable back?
     
  4. mikeddd

    mikeddd

    Nov 12, 2009
    San Antonio, TX
    What Bill said, absolutely! No offense, but going by what you posted, you have a lot to learn about speakers, cabinets and how they interact. Unless you want to be buying new speakers on a regular basis, I suggest you don't randomly do things like take the back off the cab and play it that way. The cab has a back for a reason. :)

    For grins, what cab is this? Can you post pics?
     
  5. mikeddd

    mikeddd

    Nov 12, 2009
    San Antonio, TX
    Once he broke out the cordless drill, it became a removable back cab. Just guessin' :ninja:
     
  6. Jd261808

    Jd261808

    Apr 18, 2010
    Yeah I do not know anything about speakers. This is an Emperor 2x15 with Eminence Legends in it.
     
  7. My guess would be that you have the bass knob too far up on your amp.
     
  8. Jd261808

    Jd261808

    Apr 18, 2010
    I dont get why that would happen? Never happen with any other cab with the bass knob up?
     
  9. Robby Hoinsky

    Robby Hoinsky

    Dec 28, 2010
    New Haven, CT
    Art of Noise Audio, fEARful™ builder
    Sometimes small air leaks can sound like big rattles, check that it is sealed around the back, use some caulk or weatherstripping if you have to.

    Tune your bass as low as you can and play the lowest note you can through it and get your ear right up to the seams and listen for leaks.

    Robby
     
  10. Jd261808

    Jd261808

    Apr 18, 2010
    Ok I could try that. I had tons of bass cabs in my life and never seen this before.
     
  11. Jd261808

    Jd261808

    Apr 18, 2010
    Why also does it have that sound when I hit some notes and not all notes?
     
  12. billfitzmaurice

    billfitzmaurice Commercial User

    Sep 15, 2004
    New Hampshire
    Owner, Bill Fitzmaurice Loudspeaker Design
    Lack of bracing, as I already said.
    Is the cab lined with damping? If not response will have all manner of peaks and valleys, and the lack of adequate bracing will be more apparent at some frequencies than others.
     
  13. Jd261808

    Jd261808

    Apr 18, 2010
    The backing has a felt all around the piece that comes off. Perhaps it is not enough of a sealant and is letting air out?
     
  14. Jd261808

    Jd261808

    Apr 18, 2010
    Ok so whom I bought it from, he said he thinks that the grill cloth was streched over the baffle and that is why the noise is heard. This make sense?
     
  15. JimmyM

    JimmyM

    Apr 11, 2005
    Apopka, FL
    Endorsing: Yamaha, Ampeg, Line 6, EMG
    possibly. i've had rattly grillcloth before on my b-15 cabs.
     
  16. will33

    will33

    May 22, 2006
    austin,tx
    As has been said, the cab may be a weak build that can't take it when hit with power and/or pumping speaker excursion, add to that lack of damping, etc.

    Also you say these speakers are new or have been replaced....if they were not replaced with the same original spec speakers or something else that would work well in that size cab, with that particular tuning, this may not be your only problem, just your first one.

    So what are we working with here in the first place, ie: cab type/model/measurements, tuning, speakers, etc.
     
  17. Jd261808

    Jd261808

    Apr 18, 2010
    Well he did replace the one speaker with the exact same one. Maybe it's not installed correct. And, now that I have the cab he will not answer my email. Looks I been taken for a ride.
     
  18. Arjank

    Arjank

    Oct 9, 2007
    Above Amsterdam
    Thats what is called resonance frequency. All objects have a resonance frequency, thats the frequency at which a certain object starts to vibrate with putting the least energy into it. Same as with car tyres, when they are not balanced well things start to shake and rattle at a certain speed. That certain speed "feeds" the resonance frequency of the unbalanced tyre which makes it shake.
    So in your case it's a certain frequency produced by the speaker via your bass and amp that "feeds" the resonance frequency of one of the panels from the cabinet. Like Bill said, bracing will minimize this issue.
    It might also be something else then the panel, maybe a screw or the speakerbasket buzzing against the baffle of the cabinet.
     
    Quantized Harmonic likes this.
  19. Primary

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    Here are some related products that TB members are talking about. Clicking on a product will take you to TB’s partner, Primary, where you can find links to TB discussions about these products.

     
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