Cabinet Plywood w/Voids - Secret Tone Chambers?

Discussion in 'Amps and Cabs' started by BlueRiff, Sep 14, 2016.

  1. BlueRiff

    BlueRiff Member

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    I often hear of amp/cab builders mentioning "void-free" plywood as a thing of the utmost quality. My brother and I (really him) built an open-backed, Fender style cab from Home Depot plywood which definitely had voids in the ply (2x10 cab). This cab has a warmer sweet tone than my other top quality void free cabs. especially hooking up a tube amp and running overdrive - I can't believe the projection and warmth of this thing. Have I discovered plywood "tone chambers"? Anyone else have a cab built on this type of wood? Anything I'm not considering with using "voided" ply for a cabinet?
     
  2. Haz

    Haz Member

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    I've built about 10 cabs so no more experience than that. All I can say that people overestimate / overthink concept of box with several speakers. If it's made of plywood with similar density really doesn't matter. It's all marketing.
     
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  3. LeicaBossNJ

    LeicaBossNJ Silver Supporting Member

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    The contribution of the materials and design is a lot smaller in open-back designs, no?
     
  4. guy8string

    guy8string Member

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    @BlueRiff
    It's more likely that you just built a great cab. I think sometimes we perseverate over things like void-free plywood, that--in the final analysis--contribute very little to the overall sound.
     
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  5. dbagchee

    dbagchee Supporting Member

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    I was curious so did some googling. This article seems to highlight some valid reasons why one might use the void free stuff (not to say that the cab can't sound great without it!):

    http://www.woodworkerssource.com/bl...-birch-plywood-why-its-better-when-to-use-it/

    1. Superior Screw Holding
    2. Cleaner Joinery
    3. Improved Strength and Stability
    4. Attractive Appearance
    5. Thicker Face Veneer with Reasonable Quality


     
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  6. BlueRiff

    BlueRiff Member

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    Thanks for perspective. We got lucky with this cab!
     
  7. guy8string

    guy8string Member

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    Lucky? Nah. You built a great cab.

    If you wouldn't mind sharing, what were your outside dimensions and speakers?
     
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  8. axelfoley

    axelfoley Supporting Member

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    I've built cabs with both types. The benefit of Baltic in my experience is structure not sound.
    You can dovetail, locking miter, or box joint Baltic (void free) and it's almost as good as solid wood. You can do this with plycore (Home Depot ply) also but the plycore will not hold an edge nearly as well and a locking miter is out of the question with plycore. Also if you end up with a void where you are joining pieces you'll have to fill, not ideal.
    My other thought, even though it's never happened to me, is that with plycore you're taking the chance of a rattle in your cab. Loose pieces sticking into the void.

    My .02
     
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  9. FFTT

    FFTT Member

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    Beyond structural concerns mentioned, some cabs may have issues with vibration causing a buzz at certain frequencies and volumes.

    For an open or oval back cab, I would go with dovetail joint heart pine or Italian poplar to help keep the weight down and still be strong.

    You can also go to cabinet grade hardwoods and skip the Tolex.

    Definitely have noticed the greater use of oval back cabs these days.
    Strength, full support all the way around the enclosure and improvements in relective sound off the back of the cab.
     
  10. Silent Sound

    Silent Sound Member

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    I wouldn't put too much stock in the type of wood used in the cabinets. Void free is mostly a marketing ploy, and would have more to do with long term durability than tone.

    If you're building an acoustic guitar, then the type of wood, grain of the wood, and even the finish can play a big role in the final sound you hear. So it's easy for guitarists to believe that wood selection can make a huge difference, because in the acoustic guitar world, it does. Even on electric guitars, the difference can be pretty noticeable. But for guitar cabinets, it's not such a big deal. The speaker choice is the main thing. Guitarists seem to underestimate how much two supposedly identical speakers can sound. Seriously, mic up each speaker in a standard 4x12 cabinet, and I bet you'll be shocked at the tonal difference you'll get from each of the 4 speakers. Beyond that, the cabinet dimensions make a fair bit of difference. But when it comes to the type of wood used... we're starting to get into minute, nitty-gritty stuff. At least when talking tone. Even MDF vs. solid wood vs. plywood isn't that big of a difference.

    I'm not saying that the type of wood won't effect tone, or that it doesn't matter. It does. Everything effects everything. But it's not to the degree that some people would have you believe.
     
  11. BlueRiff

    BlueRiff Member

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    Yes - good points - wood chips in the void could cause some undesirable buzz. Not the straightest of boards either - these Home Depot plys...
     
  12. FourT6and2

    FourT6and2 Supporting Member

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    Wait, so which is it. Is it a marketing ploy or does it actually have something to do with durability? Those two things seem to be mutually exclusive. It's either one or the other. Because if it's got something to do with durability, then it's not a ploy. And if it's just a ploy, then it wouldn't have any real-world benefits (like durability).
     
  13. FFTT

    FFTT Member

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    When you put so much time and effort into building a solid cab, especially for yourself to use, no reason to skimp on materials. Better materials are easier to work with.

    The weight thing is also a consideration.
    Birch ply is strong and practical, but it does add considerable, unnecessary weight, especially in combos.

    I mention Italian Poplar because it is affordable and easy to find wide plank widths.

    Bad Cat went to Italian polar for their head shells and knocked an average of 7 pounds off the weight of their head shells.
     
  14. DeaconBlues

    DeaconBlues Member

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    I've never cared for MDF cabs. I always preferred solid pine, with Baltic birch ply a second choice. Presently, I have four cabs: 2-Baltic birch, 1-solid pine, 1-MDF. The MDF cab sounds best to my ears. Could very well be the speakers in that cab, but even before I re-purposed the cab (it started life as a Peavey 2x10 vertical bass cabinet) it had a great sound as a bass cabinet. So, there is something to what Silent Sound says about materials not making that much of a difference. I still like solid pine, though.
     
  15. FFTT

    FFTT Member

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    Some people like a livelier cab, some prefer a darker more dampened sound.
     
  16. whoismarykelly

    whoismarykelly Oh look! This is a thing I can change!

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    an open back 2x10 isn't putting very much stress on the materials. The speakers aren't that heavy and they're not likely to get that loud. An open back cab isn't resonating super hard from internal air pressure. If you built a sealed 4x12 from the same materials you would probably turn out a miserably loose and rattle-prone cab that would need excessive bracing to sound good. So your specific circumstance worked well within the limits of the materials. When you push those limits you're more likely to run into problems.
     
  17. DrainBamage

    DrainBamage Member

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    A open back cab like you built would have little effect I would assume. Sealed on the other hand would be a bit different. You can knock on the wood and hear different tonal changes depending on the density and how close to the joint it is. Not enough to concern with a guitar cab for me but would want the cab void free for a strong structure.
     
  18. darkknight91

    darkknight91 Member

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    I recently built a 1x12 with run of the mill ply and it turned out just fine. I won't use it other than testing speakers, but it can be done. I just value my time and workmanship more than to use it on crappy materials.

    When using plywood with voids, you're going to eventually have problems when constructing. Cutting, routing, rabbet joints, finger joints and even rounding over the edges can reveal the voids and even have chip outs. I don't believe void free is a marketing ploy at all. When buying a cabinet at the prices they're selling at, one should expect the best materials.

    I recently stripped the carpet off an old Rivera combo and noticed it's a 7 ply with the outside being two very thin maple veneers. Finger joints and no voids. Big store plywood these days is junk. Chinese trash. I built a desk a few years back with cabinet grade plywood bought from one and it was great. No voids. Today it seems to be a special order, if you can even find it, and way overpriced. $50 for a sheet of voids and over-layered garbage is ridiculous.
     

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