building a super-light cab: what wood?

Discussion in 'Amp Central Station' started by Jupiter, Feb 23, 2020.

  1. Jupiter

    Jupiter Telefied Silver Supporter

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    I'm trying to make a light and portable rig. To that end, I bought a Quilter 101mini, and I'm running a zoom MFX pedal through the FX loop of that.

    Now I'm gonna build a speaker cabinet, to house a Lil Texas neo 12" speaker (prolly). I want it to be light, like "Jeez this is light!" light, but it doesn't necessarily have to be "blow away in a breeze" light.

    At the local DIY store they got several options:

    18mm-thick pine boards. They are not one-piece, and not veneer; they are like lotsa 1x1 sticks glued together and then sliced into boards. Dimensionally nice and stable--but not light! I've built a cab out of this once already, and it's really strong--overkill, really. I mean, that's almost 3/4in thick...

    13mm cypress (hinoki). Thinner, still pretty strong, smells good. Again, glued-up sticks like the pine, so pretty stable. But surprisingly about as heavy as the thicker pine boards. :-/ For you 'mericans, it's about 1/2" thick.

    13mm falcata (never heard of this stuff before, actually). REALLY light, and glued-up sticks like the other stuff. I got nervous when I googled it and found that it's used for matchsticks and disposable chopsticks...

    13mm paulownia. If I remember correctly, this was the only stuff that was actually not glued up pieces. Again, extremely light, but I'm afraid it's gonna be too soft. I know there have been guitar bodies made from it.

    There is also some plywood down there, but it's all housing construction grade, so there could be voids. I'm still thinking about using some 1/2in ply for the front baffle and rear panels, just to add some rigidity.


    so: any thoughts/considerations about which material is most appropriate for a very light 1x12 cab?
     
  2. trapdoor2

    trapdoor2 Tele-Afflicted Gold Supporter

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    Paulownia.. just use something to harden/protect the corners and edges. Cover it in tolex, it'll be fine.
     
  3. Chunkocaster

    Chunkocaster Poster Extraordinaire

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    Balsa? Chinese "Sycamore"? Paulownia.

    All soft but you could experiment with using wood hardener on them.
     
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  4. Whatizitman

    Whatizitman Friend of Leo's

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    Last edited: Feb 23, 2020
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  5. OldDude2

    OldDude2 Tele-Afflicted

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    Basswood
     
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  6. OldDude2

    OldDude2 Tele-Afflicted

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    Oops sorry about that but I know there are European variants, but ...?
     
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  7. rolandson

    rolandson Tele-Holic Silver Supporter

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    Nothing wrong with glue-lam planks...as long as the glue maintains it's stability over time. But the weight might defeat the desired intent.

    I don't see an issue with paulownia. I don't happen to think that soft is a negative. Pine isn't considered hard by any stretch of the imagination, yet it's held up rather well for the 53 years that my bf's have been around. However at just over ½ inch, I'd be more comfortable with box-jointing over pretty much any other.
     
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  8. Dacious

    Dacious Poster Extraordinaire

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    Ply is going to.be lightest - 12-15mm at least 7 ply. Use a piece of 10-12mm MDF as the baffle pref rebated/dadoed in. If you keep overall dimensions small it will be sufficiently rigid not to buzz and to support the speaker. You didn't mention sealed or open, but if you run two 4-6cm strips across the rear opening top and bottom it will reinforce the whole structure. You can load speaker from rear make a ply frame with grille cloth stretched over and Velcro in front.

    Pine is soft - Fender used it for cheapness not tone or longevity. A floating ply baffle also doesn't provide much support. Glued in = much better.
     
    Last edited: Feb 23, 2020
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  9. Muinarc

    Muinarc Tele-Meister

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    Basswood or Japanese beech might be light? Rumor had it my Fender Performer guitar was beech and it was real lightweight.
     
  10. BobbyZ

    BobbyZ Doctor of Teleocity

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    I won't argue that Leo probably used pine because it was affordable and also very easy to source. But as far as longevity? Pretty hard to say it's not tough enough when there's so many 50ish plus year old Fenders around in those pine cabs. And the "floating" baffle actually adds a lot of structural stiffness.
    Trouble with plywood is finding good quility sheets. At Home Depot or whatever you've gotta sort through piles of the stuff just to find a flat sheet that looks decent on both sides. You want good void free stuff you gotta order it.
    I suspect that's why Leo stopped using plywood altogether for baffles in the early 1960s. The manufactured boards are consistent if nothing else, that's one reason they've been standard fare in kitchen cabinets for years. You're not buying a pallet of 4x8s then paying a guy to sort through them and toss out unusable sheets. As long as the fork lift drivers were all careful the whole pallet is normally good. No waste, no added labor to sort it out.

    Sorry for the rant but the "Leo was cheap" thing gets me going. People that never worked on or used other amps from the time period might actually believe that's true.
     
    Last edited: Feb 24, 2020
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  11. Jupiter

    Jupiter Telefied Silver Supporter

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    I don't think I'm gonna mess with trying to glue anything over the surface, but I might spray it with some 2-pak urethane.

    They have some stuff like this at the DIY store, but everything I've seen has been warped to hell and gone. That's one of the big appeals to the glued-together stuff: it's got the rings oriented to cancel that stuff out, and it's pretty true.

    Not one of the choices! ;)

    Glue-lam! That's the word I was looking for!

    I was planning to use a reinforced butt joint, like this:
    butt-joint.gif

    That way I'm not screwing into any end grain. I built my last box this way, and like I said, it's REAL sturdy.

    Hmm, it seems to me that the falcata, paulownia and cedar (forgot to mention they had that too) would all be lighter than plywood...

    I was planning a semi-open back: basically the top 1/3 and bottom 1/3 would be reinforcement boards. I'll also mount the jack to one of those.

    I could go MDF for the baffle. It'll prolly get the reinforced butt joint, glue and screw like the pic above (or maybe no glue at first at least, 'cuz I might not like my first attempt :rolleyes:)

    The beauty of Paulownia over the others, besides lightness, is price: I think I can build the box for less than 30 bucks worth of wood. If I preserve the baffle, I could easily upgrade the box later for minimal additional outlay.

    Thanks guys!
     
  12. Chunkocaster

    Chunkocaster Poster Extraordinaire

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    Pine can be light if you get to pick the light pieces out from the bunch.

    I just put a bee box pine cab together, they are pre cut for dovetail joints and the size is pretty much identical to a 5e3 deluxe cab. Around $35 to $39au delivered.

    I can't get 10mm ply or mdf but I can get 7mm ply and 3mm melamine fronted mdf and glue them together to make a 10mm baffle, the leftover 7mm ply will be good for the rear panels.
    Total cost is $20 bucks for the additional ply and mdf sheets with a fair bit of material left over.

    The clean melamine front of baffle will look slick with a coat of matt or satin black before the grill cloth is applied and it will still have the strength of ply.
     
    Last edited: Feb 24, 2020
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  13. Guitarteach

    Guitarteach Poster Extraordinaire

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    I used 14mm pine shelving stock. Reinforced butt joints. 9mm ply for the baffle and half back panels.

    Nice and light.
     
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  14. muchxs

    muchxs Doctor of Teleocity

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    We have a couple demolition containers next to each other at the transfer station (town dump). One is "metal", the other "wood" while across the yard we have co- mingle, glass, cardboard and plain old garbage.

    The metal container yields stuff like old Jensen speakers, old tools, this winter's snow blower came out of there in big chunks as well as next summer's lawn mower.

    The wood container yields antique pine boards, vintage spruce plywood, MDF and any grade of modern plywood you can imagine at one time or another.

    Best thing I got from the wood dumpster was a 200 year old pine bureau that became a small herd of tweed Champ cabinets.

    I consistently get very light antique pine boards that were previously shelves.

    The other thing you need is a packet of ramen. You will never be hungry in the dark...

    :) :) :)

    Like everyone else says we probably have a winner.

    Pine by itself is very soft. Pine covered with tolex is exactly what Fender did and we all know how long old Fender amps look good. Paulownia should be the same deal.
     
  15. Jupiter

    Jupiter Telefied Silver Supporter

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    You ain’t lived until you’ve had REAL ramen. Throw some chahan and a half dozen gyouza down next to that and you got something lemme tell ya!
     
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  16. muchxs

    muchxs Doctor of Teleocity

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    My friend Anders is of Swedish ancestry. He looks just like his twin sister. He studied Fashion Merchandising and he ended up in Japan. I used to see him every summer when he came back to help run the church food kiosk at the County fair.

    He usually came back with a busload of Japanese girls.

    He picked out one good one and rarely comes back here, now.
     
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  17. Jupiter

    Jupiter Telefied Silver Supporter

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    SAME!
     
  18. koolaide

    koolaide Tele-Holic

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    Hey, Jupiter,
    had similar thoughts-I bought a Mooer Babybomb 30 watt pedal amp and want a lightweight setup.

    I just finished the cab. It is built of 1/2 plywood. Mitered corners (did a translucent finish) only glue in corners. A premiter frame (using ripped 2x4) for baffle and rear panel mounts. glued and screwed frame. It is plenty strong. If I had it to do over, I would use doubled ply for framing .Baffle is front loaded and screwed through back to frame.
    My thought is glue is as strong or stronger than wood. I used titebond. here is a of photo-

    P.S. Please send Yakatori from Tokyo street vendor. and a couple of Krin beers.

    cab guts.jpg
     
  19. jvin248

    jvin248 Poster Extraordinaire

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    .

    The first step in the project is get all the specs of the speaker you are planning on using then find the DIY Speaker Cabinet Design Calculators on the Internet. There are several to choose from.

    The key is calculate for a closed box cabinet. Yes, open backed guitar amps are "classic" and seen everywhere, but that is lazy design and results in a much larger cabinet and a lot more weight. There is that selling perception that buyers feel the bigger heavier item has more inherent "quality" to it (heavy Les Pauls, thick carpet on the floors of luxury cars, steel weights added to headphone sets) and thus the amp builders have no incentive to build carefully nor small nor light.

    The smaller the cabinet size, the less problems you will have from the sides and back bending with the music, so you can use thinner materials for more weight savings. You can also add bracing inside to go thinner walls yet, but you need to account for anything inside the box, including cleats, subtracting from the optimal volume.

    The small sealed cabinet acts as an air spring behind the speaker giving you much more output than hanging the speaker on a board in the open air of typical construction. Each speaker driver is different in cone volume and speaker coil throw and why you need the driver specs to plug into the cabinet calculators. I had an old speaker design book that showed how to build a fixed volume box and to test any speaker with it to determine the optimal volume needed, so that's possible but will require a little research.

    You can probably find a local cabinet shop that has a surface planer to take your 3/4 boards down to a half inch. Or a hand plane. Bandsaw resaw then plane flat.

    Can you find any glued up bamboo boards where you are at? Check the weight on those. Around here, bamboo plywood is available through special order and very expensive but where you are at it might be a better deal. Still probably heavier than Paulownia.

    You could build parts of the case with one wood and other parts with a different wood, so you use thicker/heavier/harder where abuse is likely to happen and thinner where you just need the distance spanned.

    But spend time on the cabinet calculators, you can run different scenarios open vs ported vs closed and see how the cabinet volume shrinks at each design style. Maybe even experiment with building a couple of sizes or with different materials.

    .
     
  20. Jupiter

    Jupiter Telefied Silver Supporter

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    Thanks for the pic and your experience! Unfortunately, yakitori doesn't travel very well...

    Gee, that sounds kinda complicated. :confused: I was just gonna crib the dimensions from the DV Mark Neoclassic 112. :D Specs for that, in case anybody is interested, are thus:
    WIDTH: 19.09" / 48.5 cm
    HEIGHT: 18.30" / 46.5 cm
    DEPTH: 10.63" / 27 cm
    WEIGHT: 18.3 lbs / 8.3 kg

    But I'll check out the cab calculators, just in case I can actually get away with an even smaller box. I was also thinking about angling the speaker upwards a bit, either by building a trapezoidal box or by angling the baffle...

    I don't know hardly anything about open vs closed back speakers, except I had read (and it seems logical) that closed back boxes are more directional/beamy, so I thought I'd get more dispersion from an open cab, which seemed good for my purposes (I don't expect I'll be micing this cab). But I'll read up some more on that too. ;-)

    I know there are other materials out there besides what I listed--and the bamboo glue-lam sounds really interesting actually--but I'm just planning to knock up something with whatever is available at my local on-the-way-home DIY place; they seem to have a pretty broad spectrum of inexpensive choices. I may well re-engineer it and cannibalize the parts at some point, once I get some experience with the neo speaker. I'm definitely expecting to use some different wood for the baffle and back panel(s).

    I got a feeling the first iteration of this cab is gonna be on the ugly side...
     
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