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Does this Avatar B212 need more damping? (pics)

Discussion in 'Amps and Cabs [BG]' started by mikeddd, Nov 22, 2010.


  1. mikeddd

    mikeddd

    Nov 12, 2009
    San Antonio, TX
    I have an Avatar B212 and I think it's under-damped. It's boomy to my ears. Peeking through the vent all I see is two skinny strips of 1/4" carpet pad; I thought that was the only padding in there. So I bought a foam mattress topper (about 1.25" thick) with the intention of lining the whole cab (except the baffle). Tonight I opened the cab up to start lining and was surprised to find 1/4" carpet padding on all surfaces (except the baffle). The padding is kind of hard and not really "puffy/fluffy/paddy" at all, but it does cover pretty much the whole interior. :help:

    Should I install the mattress topper on top of the carpet padding? Remove the carpet padding and install the mattress topper? Do nothing? I'm pretty shocked to find this much "padding" inside.

    Need advice, please.

    Pics:

    P1030473Large.
    P1030472Large.
    P1030471Large.
     
  2. My guess would be that if the cab sounds "boomy", it has more to do with port tuning than with cabinet wall resonance. Even if the cab sides are resonating, I doubt that adding more damping material will help. That stuff is in there to control high freqency reflections, not to stop the cabinet sides from resonating. It's not like damping a kick drum.

    I'd experiment with changng the port diameter, or just EQ.

    My $.02
     
  3. mikeddd

    mikeddd

    Nov 12, 2009
    San Antonio, TX
    Well, from what Bill Fitzmaurice has said, boominess comes from a cab that is too small. But he did say that good damping could help tame the boom. I trust what that man says about speakers & cabs. If I do nothing, I'm out $20 for the mattress pad and an hour of my time. FWIW, this cab is solid. Knocking on the sides produces a high-pitched "rap". I've been waiting for awhile to have the time to do this. Now I have a little time and this happens. /facepalm
     
  4. greenboy

    greenboy

    Dec 18, 2000
    remote mountain cabin Montana
    greenboy designs: fEARful, bassic, dually, crazy88 etc
    My god, is that a 2x4 in there?!?

    You probably have enough damping in there, but it's hard to tell without feeling the stuff. You could wrap some of what you bought around that 2x4 though - and the open space below it; }
     
  5. rpsands

    rpsands

    Jul 6, 2007
    Phoenix, AZ
    The 2x4 is crazy but leaps and bounds ahead of most cabinet bracing schemes =P
     
  6. greenboy

    greenboy

    Dec 18, 2000
    remote mountain cabin Montana
    greenboy designs: fEARful, bassic, dually, crazy88 etc
    Maybe. Ironically, not having looked inside, the one I played seemed like it was kinda mushy on the sides and top panel, though doing a knuckle test on a rat fur cab is half a joke anyway.

    It seems like not only overall rigidity is needed, but also panel damping sections when you get into larger expanses.
     
  7. mikeddd

    mikeddd

    Nov 12, 2009
    San Antonio, TX
    The padding inside has no "cushion" or "give" to it. It doesn't squish much when you press your fingers into it. We all know these cabs are built to a pricepoint. Overall I'm happy with it, but not deliriously so. I'm a tinkerer by nature. If I can make it better I want to try. This cab is tolex covered, so I would think the "rap test" should carry some weight. ;)

    By summer I'll be in a house with a garage and my tools again! I will build a fEarful 15/6. But for now this is it.

    So based on my oh-so-scientific explanation about the stock padding, what should I do? I may swap it out anyway...but would like some opinions.
     
  8. greenboy

    greenboy

    Dec 18, 2000
    remote mountain cabin Montana
    greenboy designs: fEARful, bassic, dually, crazy88 etc
    I've seen two things that look like that, and one appears to be a wool and mixed fibers matt, and the other actually is THAT. The second is definitely a good absorptive/damping material. The other may or may not be lacking in density for lower thicknesses like you have. But I'll say it again, leave what's already there, just wrap the 2x4 and cover the open area (and if there are other open areas like the top of the shelf cover them with your mattress topper too.

    I suppose if you are bound and determined to use some more foam, spray lightly the existing damping JUST on the back panel and press/apply a layer of foam over that.
     
  9. mikeddd

    mikeddd

    Nov 12, 2009
    San Antonio, TX
    Thanks very much, greenboy. I appreciate your advice. I'll do what you suggest.
     
  10. greenboy

    greenboy

    Dec 18, 2000
    remote mountain cabin Montana
    greenboy designs: fEARful, bassic, dually, crazy88 etc
    mike,

    I've had a couple cabs with wool/felt material in them. And though that doesn't give like most open cell foam - it is instead porous yet dense - that's what we are really looking for is damping properties.

    But I feel ya. There's been a few times I've actually lined a cab, listened extensively, relined it double-layered, listened some more, then removed part of the second layer to get them sounding "just so". But for an MI cab that's probably overkill.
     
  11. mikeddd

    mikeddd

    Nov 12, 2009
    San Antonio, TX
    I was so SURE that there was only those two little strips on the back panel...imagine my surprise when I opened it up! We'll see what happens with just the brace/open spots/rear panel covered. I know the sound of this cab pretty well, so if it's better or worse I should pick it up immediately. It probably won't sound any different, but my inner geek will be satisfied. For now. Summer's coming and there's a 15/6 or maybe a 1515/6/6 in my future. :D
     
  12. billfitzmaurice

    billfitzmaurice Commercial User

    Sep 15, 2004
    New Hampshire
    Owner, Bill Fitzmaurice Loudspeaker Design
    Add more damping. What's in there is thick enough to control midrange reflections but not midbass boom. A boomy cab will need over an inch of damping, maybe two inches.
    As for bracing, IME there should be no more than an 8" radius of unbraced panel. Directly connecting panels with dowels or stock works very well. But using a 2x4"? From that one board one could make four braces spread about, with literally twice the effectiveness from the same mass.
     
  13. mikeddd

    mikeddd

    Nov 12, 2009
    San Antonio, TX
    Hi Bill, I was hoping you would chime in. So you think I should add mattress pad on top of the existing padding on all surfaces? I didn't do anything with the cab last night so it's still taken apart. Staple gun is ready to go. Thanks very much!

    Mike
     
  14. recreate.me

    recreate.me

    Apr 2, 2010
    Ontario
    Weird, i just bought the same cab, and i don't get any boom out of it. I do hear a mid scoop, which makes the bass seem louder.... I wonder if all avatar cab are the same inside, or maybe you got a dud..
    Did you call Avatar back and tell them there sold you a boomy cab?
     
  15. mikeddd

    mikeddd

    Nov 12, 2009
    San Antonio, TX
    It's not a "dud." This cab is what it is; a little too small for two 12's. But I didn't know that before I bought it...this is my first bass cab. For the money, it's almost impossible to beat. To buy a NEW 2 x 12 that's better would cost you twice the money, easily. But you know this already. ;)
     
  16. Growly Lytes

    Growly Lytes

    Dec 4, 2009
    Downunder Oz
    Bass player
    Try to get some Carpet underlay.They use it underneath carpet for padding before they lay the carpet.Its 100% foam & cheap.I had some boom but after doing the padding it improved the sound.
     
  17. mikeddd

    mikeddd

    Nov 12, 2009
    San Antonio, TX
    Growly, do you have a B212 too? Did you add padding on top of the existing padding or replace the existing padding?
     
  18. recreate.me

    recreate.me

    Apr 2, 2010
    Ontario
    Let me know what happens on this, if you get a really noticable tone change maybe i will give it a try. I didn't think my cab was boomy (my ampeg 410HLF was!), i thought it was tuned really low, but i might be wrong.
     
  19. mikeddd

    mikeddd

    Nov 12, 2009
    San Antonio, TX
    I'm actually looking to make a formal report on my results. I recorded a few clips of my lousy playing with the stock cab. Once the cab is stuffed, will play the same clips with the same exact setup (amp settings, microphone distance, etc).
     
  20. Growly Lytes

    Growly Lytes

    Dec 4, 2009
    Downunder Oz
    Bass player
    No i dont have that cab.I made 2 quadboxes with BP102speakers unfiltered no tweeter & midrange or crossover.I tuned to around 40hz.
    Found that it was boomy at first & pretty airy not a solid clean sound, i cant explain it exactly but it wasnt what i expected off the bat i suppose you would call it mud.I was then told by TBers to add foam to clean up the boom.Well it worked !! I found that it took the boomyness away pretty much & sorta compressed the sound a little, at least thats what it seems like. Though it did take away a little bit of high end. Whatever BFM says in this field is right on the money, take whatever he says & run with it.
     

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