fEARful™ Part Eleven (11)

Discussion in 'Amps [BG]' started by Kelly Lee, Apr 8, 2011.


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  1. Kelly Lee

    Kelly Lee Yeah, I'm a guy! Supporting Member

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    Marana, AZ, USA
  2. Sundogue

    Sundogue

    Joined:
    Apr 26, 2001
    Location:
    Wausau, WI
    Since my last post was in part 10, and I feel it is important and don't want it to be missed, I'll repost it here...

    Vibrations...
    I was still experiencing some vibrations I could not account for.

    I knew the ball bearings in my wheels were rattling at high volume although I never really heard it playing live, only in my living room.

    However, I was getting some weird vibration going on when I played some deep notes or if I did a faster run on the E or A strings...at high volume. If I put my hand on the back I could feel the back resonating pretty severely. If I pressed on the back hard or put my foot against it, it went away for the most part. The massive vibration is only on the back panel and I did all the bracing according to plan...even the additional bracing!

    So anyway...I was going to put some skids on the back because I always slide my fEARful into my truck on it's back and the back was getting scraped up a bit. Well, I put the skids on today (made from 1X2 oak strips...actual .75" X 1.5") and I am finding that ALL the vibrations are completely gone. Even the bearings in my wheels don't rattle anymore. When I crank it and play hard through it, there are absolutely NO vibrations to deal with at all.

    If I were to build another 15/6, I would definitely add vertical bracing similar in placement to my skids, only on the inside (see pic below). I feel it makes a HUGE difference. I could have taken the speakers and foam out and added bracing but since I was going to add skids anyway this is just perfect.

    I'm not sure if anyone else is experiencing back panel vibration at high volume, but if you are...add vertical bracing inside on the back panel between the edges and the brace in the middle. I think you'll notice a big difference.

    Haven't painted the skids yet...just got them on and tested. I caulked the underside of them, pushed them on tight and used 7 screws per skid so that it was rock solid tight to the back (wanted to eliminate any vibration of the skids themselves). I love it! I can literally crank my amp through this beast and it is SOLID.

    [​IMG]
  3. Corporate Boy

    Corporate Boy

    Joined:
    Feb 12, 2008
    Location:
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    I'm really interested in the Fearful Cabs. There is a lot of good information locked in all of these threads. Anyway, we can organize it better?

    Maybe a threads like fEARFul - Crossovers, fEARFul- Cuts, fEARFul - finishes, fEARFUL - General disucssion?

    Just a thought.
  4. Sundogue

    Sundogue

    Joined:
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    Location:
    Wausau, WI
    I should add that vertical internal bracing between the sides and the middle brace of the back panel reduces the span from about 10" wide down to 5" which will eliminate vibrations even more.

    But...because there is no bracing below about the midway point down to the bottom on the back panel (due to the port opening), aside from the single vertical brace running down to the port brace on the bottom, I find that my skids beef up that huge open span of the lower half of the back panel. It reduces the span from about 10" wide by almost 15" high, down to 5" by 15".

    Aside from serving as skids I really feel it adds some needed bracing on the bottom of the back panel. That may explain why my wheels don't vibrate any longer either.

    I'm sure it won't be noticed as much if anyone puts there cab right on the floor or doesn't really crank it hard. But I'm using it in a pretty darn loud classic rock band and I'm putting 800 watts into it (not constantly of course, if at all). But at high volume with some lows boosted some may notice the back panel vibrates more than it should. I did try EQ'ing some of the lows out and that did the trick as well somewhat, but I like the lows this cab puts out and that the fEARful can handle it.

    I'm not questioning greenboy's design in any way. Just thought I'd put it out there. I should note that I used 1/2" Arauco plywood which only has 5 plies and that may have something to do with it as well.
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  6. Sundogue

    Sundogue

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    You wanna volunteer? :D

    Most everything one really needs to know is in the TB Wiki or on greenboy's site.

    Just build one. The only question is, which one? This is not your daddy's 115. There isn't another 115 out there that can match the output and clarity of a fEARful 15/6. The only one that comes remotely close is Avatar's TB153 and that is only because it uses the 3015LF. It's way heavier than a fEARful, it does not use the 18Sound mid driver, the precise crossover and in more subtle ways, the same port tuning or driver alignment. I'm not knocking the Avatar, but for one that comes closest to a fEARful, it still isn't the same.
  7. Bardley

    Bardley

    Joined:
    Nov 16, 2007
    Location:
    Louisville, KY
    3015lf out for delivery today! :hyper:

    Now to get the $ together for the rest of the stuff for my 15/6. :atoz:
  8. BurningSkies

    BurningSkies Supporting Member

    Joined:
    Feb 20, 2005
    Location:
    Seweracuse, NY
    Huh. I'm a bit perplexed at the vibrational trouble. I think you may have nailed it with the plywood thing though. This is not something I've experienced with mine played loud. My cabs are both birch and my back panels are glued & screwed.
  9. Sundogue

    Sundogue

    Joined:
    Apr 26, 2001
    Location:
    Wausau, WI
    Did you already order the 18Sound mid? Don't skimp on that part. I was going to use a cheaper mid, but I am thrilled I didn't. That 18Sound mid just makes the cab come alive! Well...so does the 3015LF and the right crossover, but that mid is just as much a necessity IMO.
  10. Sundogue

    Sundogue

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    Yeah mine is heavily PL'd and screwed to survive an earthquake (which my playing at a high volume is kind of like :p).

    I followed the plans AND added the recommended additional bracing. Just wanted to throw it out there. So yes, it could very well be the 5 ply Arauco.

    greenboy does mention adding additional bracing if you intend to throw a lot of power into one and/or you use cheaper plywood. So that makes sense. I'd be interested if anyone else used Arauco and noticed this back panel vibration.

    All I know is the added skids on the back eliminated it entirely.
  11. Coolhandjjl

    Coolhandjjl Supporting Member

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    Oct 13, 2010
    Location:
    Appleton
    I'm screwed as far as room vibrations go in my practice space. One of the walls is..................TIN!!!! :p
  12. Bardley

    Bardley

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    Nov 16, 2007
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    Louisville, KY
    I plan on buying it VERY soon. I wouldn't build it without it. ;)
    Hoping to get a flat pack from Leland as well.
  13. PhiDeck

    PhiDeck

    Joined:
    Mar 9, 2010
    Location:
    Sarasota, Florida, USA
    Greenboy:

    I find Sundogue's above posts very interesting. They lead me to wonder whether you performed any Modal Analysis, presumably using Finite Element Models (?).

    I hasten to add that I am an EE, not an ME, and am unqualified to volunteer.
  14. Sundogue

    Sundogue

    Joined:
    Apr 26, 2001
    Location:
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    As I mentioned, I'm not questioning greenboy's design AT ALL. I did use Arauco and those who have used it know it is only 5 ply, light and prone to warping. Any of those things could have an effect on vibrational damping characteristics that have nothing to do with his design.

    Also, I am quite anal about things. I've used it on two VERY loud gigs with nary a problem. I've just noticed it in my living room isolated from other instruments/sounds.

    And, unlike a great majority of bass players I don't live or die by boosting lower mids in place of low end (as most who use commercial cabs seem to want to do to be heard). I have some boost from 50Hz on up to 100Hz and I play quite loudly. All contributing factors.

    All I know for sure is I had vibration that not only could I hear, but could really feel on the back panel (and nowhere else). After attaching the skids it was gone. And greenboy did mention in his "additional bracing" suggestions to actually feel the panels when playing to see if any additional bracing might be needed.

    I'd like to hear from others who used 5 ply Arauco or some cheaper plywood and play at high volume, if they've noticed it. I may also have some voids in the Arauco back panel that I could not see. Hard to tell. lots of factors come into play.
  15. Queg

    Queg

    Joined:
    Nov 20, 2009
    Location:
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    It might be a contributing factor, but my 15/6 tube is Arauco 1/2" as well, and I don't notice any exceptional vibes as described. Of course, the tube form factor is more squat than the traditional 15/6 box. I also did a quick "knuckle test" of the cab after completion, and the lower back panel was not as solid & dead sounding as I would like, which prompted me to open it back up and glue in a couple of vertical braces on either side of the center spine.
  16. Sundogue

    Sundogue

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    Apr 26, 2001
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    A question for greenboy perhaps...

    Would vertical bracing on the lower part of the back panel (down past the port), affect the port at all?
  17. wcriley

    wcriley

    Joined:
    Apr 5, 2010
    Location:
    Western PA
    Disclosures:
    Uncompensated endorsing user: fEARful
    I haven't had much time to work on my kit-cab and haven't updated my build thread/blog for a while.

    Disclosure: I got a discount on my 12/6 Flatpack Kit because of my small role in hooking Leland up with Greenboy. I have no financial interest in SpeakerHardware other than as a satisfied customer.

    My kit was a prototype and Leland's first go at shipping an arauco fEARful kit. Several of my panels warped after they arrived (mainly due to the way I stored them). I think Leland has now added more biscuits to aid assembly if any of the panels warp. I'd advise that when the kit arrives it be stored unopened on a flat surface (maybe weighted down) for a few days at constant temperature and humidity. I'd also recommend that you assemble the entire outer shell in one sitting. (Shouldn't take more than a couple of hours, even if you've never done this sort of work.)

    In a nutshell: This is a great deal for anyone who lacks the tools/confidence/whatever to cut the wood themselves. All you need is the time, a couple of C-clamps, wire for the internal wiring, a screwdriver, a drill for pilot holes, some putty or bondo, sandpaper, grill, and your choice of finish. Unless you order the Xover prebuilt, you'll need some zip-ties or hot glue to hold down the coils. If you use the assembly method that BFM recommends in the plans for his cabs, you'll also need some drywall screws.

    A router with a roundover bit, electric sander, and a couple of bar clamps are helpful, but not necessary.

    As with everthing Leland sells, he includes all the fasteners for mounting the hardware: screws/bolts for the corners, handles, jack plate, Speakons, etc. (He even includes "hole plugs" if you order 1/4" jacks.) With the fEARful flatpacks he includes a small plywood brace for aligning the panels square with one another.

    I haven't seen his assembley instructions, but based on what I know about the man, I expect they're thorough and easy to follow. He plans to have Youtube videos available in the future.
  18. Sundogue

    Sundogue

    Joined:
    Apr 26, 2001
    Location:
    Wausau, WI
    +1 to Leland at speakerhardware!!!

    I should note that you don't even need a router with a roundover bit. I used my belt sander and wouldn't have even needed that as the edges can be sanded down, even by hand (though that is time consuming). Thought I'd mention that to some who aren't builders and may not have, or want to buy a router.

    And you don't even really need to know anything about wiring really either as Leland offers pre-built crossovers you only have to connect. Leland has everything anyone could need!!!
  19. Queg

    Queg

    Joined:
    Nov 20, 2009
    Location:
    SF Bay Area
    I assumed the 1/2" bracing wouldn't affect the port too much.. it's not impeding air flow or taking up much volume.. of course horizontal bracing would be a problem... Interested to hear from greenboy or other experts..
  20. Jazzdogg

    Jazzdogg Less barking, more wagging! Supporting Member

    Joined:
    Jul 29, 2006
    Location:
    San Diego, CA
    As a woodworker, I like your skids!

    For others who may want to add skids, UHMW (Ultra High Molecular Weight plastic) also works very well; it doesn't splinter or require a finish, and is inherently "slippery." Plastics suppliers and retailers like Rockler sell dimensional blocks. In 3/4" thickness, it is rigid enough to effectively brace a cabinet's back panel.
  21. Sundogue

    Sundogue

    Joined:
    Apr 26, 2001
    Location:
    Wausau, WI
    Thanks. All edges are rounded and the screws are countersunk.

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