More thoughts on cabinet bracing

Discussion in 'Amps [BG]' started by MrBonex, Sep 25, 2011.


  1. MrBonex

    MrBonex

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    After reading some other threads about cabinet bracing here on TB, I thought I might add my experience to the pot.

    My rig: Trace Elliot V300H (or V6), 2 x SWR 12 Packs (most often I just use one), and of course: Fender Custom Classic Jazz Bass.

    The 12-Packs are well-made (11-ply birch), somewhat braced, well damped, and very efficient. While I love the tone of these boxes, I noticed that when the volume gets loud, things got -- I don't know -- looser. The tone literally changed -- and not for the better. I always attributed that to the amps or the drivers. Then, after reading these threads about bracing, I thought I'd take a look at these bins and see what was up.

    Sure enough, there is no front-to-back, top-to-bottom, or side-to-side bracing. Well, there is the shelf port which is a brace of sorts. And there is a perpendicular bar brace on the baffle. Looked like a tweak opportunity!

    Now, I'm old and not in the mood to add weight to bins that already weigh 66 lbs. each. So I thought, "carbon fiber?" Yeah, but it's pricey. Who makes pre-fab carbon fiber tubing that is durable, easily procured, and cheap? Lightbulb moment: arrows. Longitudinally very strong, extremely resistant to compression, mass-produced, self-damping. Perfect.

    Went to Kittery Trading Post bought some Beman large diameter carbon arrow shafts. Got some epoxy and went to town. I doubled them up (two per brace, epoxied together -- side by side).

    Results: Okay. Look folks. There's been a LOT of disagreement about the value of bracing and designing cabs to work "best" without bracing, etc. Here's the deal: it makes a difference. Whether you care or not is up to you -- but it makes a difference -- and it's frikken' audible. It's not debatable. It was almost as big as swapping amps from Ampeg to Genz. Not quite, but big. This is what I heard:

    Dry. It's like someone removed a gallon of water (!). At low volumes, I now have to add bass to warm it up. It's so cool and controlled. Live and on-stage, it's HUGE -- as though the bin was bigger. I can add bass and it will just fatten up without flabbing. I would never have called these bins flabby, but after bracing, it was clear that that was the case to an audible degree.

    Another way of looking at it is that speaker bins have a signal-to-noise ratio. The signal is the drivers, the noise is the vibration of the bin. As it got louder, the vibrations of the enclosure affected the tone in a more unmusical manner. Bracing nullifies that effect and improves the signal-to-noise ratio!

    Guys 'n' Gals: just do it. Don't think about it. Don't worry about whether bracing will make things worse. It won't. It's not hard. Measure accurately. Use lots of epoxy but be tidy. It's cheap, easy, effective. Took me just a few hours. And the carbon fiber arrow shafts added maybe 3 oz. to the bin! In fact, I would be hard-pressed to think of any mod you could make to your equipment that had a more effective price-to-performance ratio.

    Obviously, some bins are made with great bracing. If yours is one of them, you can ignore my rant. Special snaps to the folks that recommended this line of thinking!!!!

    Peace.
     
  2. Holliwood

    Holliwood

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    I like this.
    Simple, cheap and effective.
    That's some first rate DIY ingenuity rite there folks.
     
  3. JGR

    JGR The "G" is for Gustav Supporting Member

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    I had a pair of those and still have a pair of the 12-stack 4x12s. They are cool cabs and well built. The biggest limiting factor are the drivers since their Xmax is pretty low; if memory serves, it's around 1.7 mm. They are designed to compress and grind in and old school way as you know. I modeled the cabs in WinISD a few years ago and Betas worked well. I changed them in one of the cabs (need to get around to the other one) and it was a nice improvement. Still keeps the overall tone of the cab, but you can drive it harder before things compress too much and fart. Betas are pretty cheap and a worthwhile upgrade foe these cabs IMO.
     
  4. jungleheat

    jungleheat Banned

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    Sounds like a good idea. I'm considering using something like Dynamat inside some of my cab (probably in addition to some Dacron like material), with the aim of making them less "ringy" (should serve the same basic function as bracing, lessening the vibrations of the cab itself). I'm also looking at damping the metal grills, especially on the Trace cabs. I have an idea for that as well, but I need to do some "field tests" first.
     
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  6. anonymous02282011

    anonymous02282011 Guest

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    adding damping material is quite different from proper bracing.

    damping defeats sonic reflections from the interior walls of the cab back at the speaker.

    bracing keeps the cabinet stiff so that vibrational energy isn't "absorbed" by the box itself.

    Problems with either one will usually result in unique problems.

    Here's some damping material you may want to try:

    DBR Spkr. Damp.

    no affiliation other than being a happy customer. the store was recommended to me by [all hail] Greenboy.
     
  7. jungleheat

    jungleheat Banned

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    The dynamat and insulation would serve somewhat different purposes. Dynamat is like a flat, rubbery substance that's adhesive on one side (usually comes in "sheets" or rolls). You apply it to surfaces and it deadens the vibrations of that surface, so in that way it's functionally pretty similar to bracing, but without adding as much weight. It's mainly used in car audio applications where people will put it on surfaces like the inside of a door or trunk lid. But I've used it for other things as well, for instance, for a long time, my main stereo equipment rack was a set of "bakers shelving" from Ikea. Being just wire shelves, it was really ringy, and since I didn't want it vibrating with the speakers, I put sheets of dynamat across each shelf, which really worked quite well. Now instead of that metallica ringy sound when you rap on it, it sounds more like a piece of wood, with more of a "thunk" sound.

    So I would use the dynamat on the inside of the cab panels themselves, and then fill in the insulation over that.

    That speaker insulation link looks really good (and cheap). I will definitely keep it in mind, thanks!
     
  8. Tunaman

    Tunaman Supporting Member

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    I just wanted to give a +1 to the Kittery Trading Post. Grew up in Kittery & my little league team was the good ole KTP.

    The GK NEO series vs the MBE series have the same speaker... NEO has bracing MBE not & most would agree theres a difference between those cabs.
     
  9. Muziekschuur

    Muziekschuur

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    Balsa wood is light and has, when glued to the inside of your cab, the same effect.
     
  10. MrBonex

    MrBonex

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    Holliwood: Thanks for the compliment.

    JGR: Nice to meet others with these bins. I am aware of the "limited" nature of these drivers, but what I was hearing was not cone cry, over-excursion, or compression. I heard this phenomenon whether I was using both boxes or one. V6 or V300H. The bracing seems to have eliminated the effect completely. Cool about the Betas. Have you analyzed any neo drivers for these bins? I gotta think about my back!

    Muziek: I don't think a stick of balsa has anywhere near the compressive strength as a carbon arrow shaft. And, if I'm not mistaken, the kind of stresses a bin brace is subjected to would be compression (among others). But I'm not an engineer. However, I might be able to play one on tv!
     
  11. billfitzmaurice

    billfitzmaurice

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    +1. Balsa will literally stretch and compress, so it's not a viable bracing material. But standard birch dowels work well, and need not be more than 1/2 inch diameter, so they won't add significant weight.
     
  12. anonymous02282011

    anonymous02282011 Guest

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    I've seen the Dynamat stuff around; I don't think it's a good substitute for proper bracing, in that its supposed to "deaden" the way that damping material does,which is different than deadening box vibrations.

    So my inclination would be that the Dynamat wouldn't be a substitute for proper bracing and would be redundant to adding damping material, but I certainly don't want to discourage you from experimenting.
     
  13. billfitzmaurice

    billfitzmaurice

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    +1. Dynamat is a good material for damping vibration in flimsy enclosures where bracing isn't an option, as in car doors. All it adds to well made well braced cabinets is extra weight and cost.
     
  14. Oobly

    Oobly

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    +1, absorbing the vibration with Dynamat is not as good as using bracing, for the simple fact that energy which is absorbed is not available as sound any more, so the efficiency goes down. Dynamat and damping will both reduce resonance, but for different reasons. With damping, the particular frequencies are "damped" on their way between the cab panels, like a car shock absorber, with Dynamat they are absorbed, after being transferred to the cab panel. Subtle difference, but damping and bracing are better.
     
  15. JGR

    JGR The "G" is for Gustav Supporting Member

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    IIRC, the S2012 ( or maybe it was the 2512, can't remember) actually performed better than the Betas, but they were more expensive even before the Neo price hike which is why I didn't go with them. They should be the ticket; you would shave about 10 lbs off.
     
  16. MrBonex

    MrBonex

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    Bill,

    You're completely right. I know that I could have used birch dowels. But I wanted to be clever! The downside is that I could have screwed up with the installation and had a built-in fuzz box from spurious vibration. The upside is that I could talk about effective, economical, and cool, carbon-fiber enclosure bracing.

    It was worth the risk!

    :D
     
  17. 1n3

    1n3

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    Arrow shafts... would never have thought of it. I'm sure birch dowels would work well too, but your solution is more elegant, and... clever. Your before and after descriptions are very interesting. Thanks for a great post.
     
  18. tabooze24

    tabooze24

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    Another option would to use a non-tapered carbon fiber hockey shaft for two piece hockey sticks (i.e. Easton hockey makes them).
     
  19. billfitzmaurice

    billfitzmaurice

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    Or golf club shafts or ski poles. There are many options, but dowels are readily available, cheap, and easily installed.
     
  20. MrBonex

    MrBonex

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    Great idea. I'm sure the Easton hockey stick shaft would be unbelievably strong. The problem is that they cost over $100 each! Phew!

    The Beman arrow shafts are made by Easton -- to a slightly lower standard of straightness than the Easton arrows. So they're a little cheaper. And as a bin brace, I didn't think I needed to worry about hitting a bullseye from 50 yards!

    Same materials, same manufacturing methods. Easton just picks the perfect ones, puts their name on it, and the "lessers" become Beman. At least that's how I understand it.

    Still, cool suggestion.
     
  21. helenforsdale

    helenforsdale

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    For cheap carbon fiber rods:
    http://www.goodwinds.com/

    I need to brace my 2x15 Mesa cab - I don't have the slightest clue as to do this. Can't find a thread w detailed instructions. Of one of y'all would point me in the right direction, I'd be much obliged.
     

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