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Advice Please: 1x15 Cabinet Build

Discussion in 'Shock Brother's DIY Amps' started by pjohnny, Aug 10, 2017.

  1. pjohnny

    pjohnny TDPRI Member

    66
    May 10, 2015
    Iowa
    A guitar buddy of mine has an old 15" Jensen k130 and wants an inexpensive plywood open back cab for it. I've never built a guitar cabinet before but that's never stopped me on any project before so we're going to take a crack at it.

    I figured I'd ask the experts before diving in.

    After some research I was thinking 24x20x12 should work at fit nicely under his 24" Fuchs head.

    3/4" plywood. Veneer for the ply edges. Handle. Corners. Feet. Jack. Grill cloth.
    There are plenty of 1x12 open back cab instruction sets out there. I am assuming that I can just work off of that as open back cabs need a lot less math than closed.

    What am I forgetting?
    Any tips on vintage-ish silver grill cloth?

    Big question: front load or back load the speaker?

    Thanks for all the help!
     

  2. Nickfl

    Nickfl Tele-Holic

    711
    May 24, 2016
    Florida
    Tolex, if you want a natural wood finish, use real wood not plywood. If you are going to use plywood, find someplace local that sells real baltic birch ply (comes in 5x5' sheets, not 4x8), don't use home depot plywood, the realy BB ply is much, much stronger than the home center crap, and isn't really any more expensive if you can find a good plywood wholesaler who will sell to the public. I always back load the speaker, that way you don't have to make a separate frame for the grille cloth.
     
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  3. Big Steve

    Big Steve Tele-Holic

    707
    Apr 24, 2006
    Here are some common dimensions from the Weber Speakers site.

    https://www.tedweber.com/media/cabdims.pdf

    You can experiment with the back opening to add or subtract more bass. I usually make a couple extra panels and figure out what sounds he best.

    For the speaker, the K130 is a JBL. The JBL is much heavier than the similar Jensen. Use plywood for the speaker baffle. If you are using the heavier JBL, I would go 3/4". If it is the lighter Jensen, I would go 1/2".

    For the box, I like the tone of pine solid boards rather than plywood. They cost about the same, if you buy good plywood.
     
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  4. Bill Moore

    Bill Moore Tele-Holic

    Really, 3/4" scrap plywood covered in tolex works fine!
    3/4" x 1.25" wood strips to hold baffle, (1/2" ply), and rear cover if desired. I used biscuits to build a head, and cab for this little practice amp, sounds great!
    PB12.jpgt.JPG
    PB7.jpg.JPG
    EDIT:
    I will add that I like to semi enclose the back of a cab for the extra bottom end it adds. It seems similar to a combo on a small stage with the back against the wall, vs a large stage with nothing behind it. (I used to use the PA rack covers behind the guitar cabs on large stages.)
     
    Last edited: Aug 10, 2017
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  5. Axis29

    Axis29 Poster Extraordinaire Ad Free Member

    Jan 2, 2007
    Virginia, USA
    Baltic Birch plywood is not inexpensive....

    However, I would recommend not going with the sanded ply at HD or Lowe's. Try to grab their birch or maple plywood. It's not voidless, but it is a MUCH better quality. I have built a couple of cabinets out of the stuff, speaker cabinets even!

    I use 3/4 for the case and as thin as I think I can get away with for the baffle... But, I am convinced a thin baffle makes for a livelier cabinet and I like that. I have no science or real knowledge to back that up, or even any real world experience with a tight, heavy baffle... I've just had good luck with what I've tried so far.

    As for edges, the veneer stuff is pain to work with... Much easier to buy a strip of poplar and rip it down to a thin 1/8"-1/4" strip or buy screen molding. The Poplar is the sturdier option, but both will work just fine and stand up so much better than veneer!

    I've done biscuits, finger joints, dovetails, etc. But, the best, fastest, just as solid as any other joint I've ever messed with is pocket hole screws. I have a Kreg brand system I've been using for at least 15 years now. That and a little wood glue, solid, reliable and easy to do.


    Grill cloth can be had at many online vendors or on eBay. I have some aged silverface cloth form Mojo that looks accurate.

    Backloading a speaker on an open back cabinet is a no-brainer. Otherwise you'd have to mess with the grill cloth if you ever had an issue or just wanted to change the speaker.
     
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  6. Despres

    Despres Tele-Holic

    665
    Aug 14, 2012
    Northeast again
    If you are going to cover it, Lowes has Poplar plywood that has significantly more plies than the other 3/4 plywoods available at the home centers, I used it for the structural components of a van buildout I did as it is pretty strong. When stained or varnished, it has a gross greenish poplar color though, so unless you're using tolex or want an ugly cabinet, it might not be suitable.
     
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  7. jsnwhite619

    jsnwhite619 Tele-Afflicted Ad Free Member

    Sep 10, 2013
    Georgia
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  8. jsnwhite619

    jsnwhite619 Tele-Afflicted Ad Free Member

    Sep 10, 2013
    Georgia
    Also, speakerbuildersupply.com parts-express.com. And amplifiedparts.com will have everything you need for hardware.
     
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  9. pjohnny

    pjohnny TDPRI Member

    66
    May 10, 2015
    Iowa
    Perfect! Thanks everyone! This is exactly the sort of advice that I need.
     

  10. SacDAve

    SacDAve Poster Extraordinaire Silver Supporter

    Age:
    66
    Dec 23, 2009
    Rocklin Ca.
    This is a cab & amp I built (5E3) The wood is canary wood, canary wood is very hard kind of like maple so the Amp is really bright , guess you could say icepick bright. Not my best sounding Amp. But if you going to do a natural finish I would consider Alder, Pine, mahogany, walnut or cheery as a good choice they all have about the same density. As for plywood’s I'm not a big fan of the big box store plywood’s but if your going to cover it with telex it should be fine. The 5 X 5 birch ply is great stuff I like the 1/2" for baffles. But it’s also very dense so you might get a bright sound. You might want to read up on Baffle construction and what the best materials are. (Then you'll be really confused) That all being said the fact is Cabs have been built from high dollar solid woods to cheap particleboard and they all work. One thing you can do is experiment with baffles fairly low cost , then when you find the right one cover it.
     

    Attached Files:

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  11. pjohnny

    pjohnny TDPRI Member

    66
    May 10, 2015
    Iowa
    Makes sense. Thanks!
     

  12. Dacious

    Dacious Friend of Leo's

    Mar 16, 2003
    Godzone
    MDF is great as a baffle material for heavier speakers because it won't flex and distort the frame. I'd never use it for the actual cabinet as it can split where it's joined just by looking at it, seemingly. Plus if it gets wet it swells and disintegrates.
     

  13. pjohnny

    pjohnny TDPRI Member

    66
    May 10, 2015
    Iowa
    That's interesting. I'll have to give that a try sometime. Thanks!
     

  14. pjohnny

    pjohnny TDPRI Member

    66
    May 10, 2015
    Iowa
    Update:
    Just ordered the needed elements from www.parts-express.com as the prices seemed pretty similar on all the sites but they had $6.95 shipping which saved me about $10 over the other guys.
     
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