filmboydoug Posted July 12, 2006 Share Posted July 12, 2006 So if I walk into a lumber yard and ask for void free plywood can I trust that it is indeed void free? What about the locally owned yards that charge more but to cater to pro builders? When I talk to the kids at home despot they are so unknowing I think they would fit right in as a best buy employee. Quote Link to comment Share on other sites More sharing options...
Guest " " Posted July 12, 2006 Share Posted July 12, 2006 What are you thinking about building? May be helpful to provide useful info. Quote Link to comment Share on other sites More sharing options...
jorjen Posted July 12, 2006 Share Posted July 12, 2006 Filmboydoug, Don't ask for "void free" plywood. You could wind up with a product from China. It is said to be void free when in fact it is not. Not as dense as it should be either. I used it on my CornScala project and wound up cross bracing the cabinet and cabinet back which one should not HAVE to do with a box that size. Just did not feel it passed muster without bracing. Ask for Russian, Finnish or Baltic Birch ply. The name that the places I go to seem to recognize most is Russian. If you cannot find anyone(including cabinet shops)that stocks it, they can order it from their distributor. It is available in various thickness/plys from 1/8" to 3/4" approx. Sometimes it is sold in metric dimensions only, so take your tape with you. Unless of course you have the conversion table commited to memory. [] Oh, just caught the blurb under your avatar. That's from the movie "O Brother, where art thou?", right? Quote Link to comment Share on other sites More sharing options...
WMcD Posted July 12, 2006 Share Posted July 12, 2006 Appleply is sometime mentioned as some of the best plywood. I've not used it myself. You can Google (for information) and perhaps a shop local to you will special order, if you're intereted. I have seen the stuff from China at HD. Very poor quality. The U.S. made stuff at HD sometimes looks okay. There are no or few voids showing at the edges. I check for warps, loose ply, funny noises, etc. I also buy at a woodworking shop. "Woodworld" in north Dallas. They certainly know their stuff. The high quality ply is expensive. OTOH I figure the cost is a small fraction of the overall investment particularly when one's own time is considered. Gil Quote Link to comment Share on other sites More sharing options...
Mighty Favog Posted July 12, 2006 Share Posted July 12, 2006 Might want to google "Marine Plywood" too. Quote Link to comment Share on other sites More sharing options...
filmboydoug Posted July 12, 2006 Author Share Posted July 12, 2006 Oh, just caught the blurb under your avatar. That's from the movie "O Brother, where art thou?", right? Yup. One of my all time faves. And I live in Fargo so it kind of fits. Quote Link to comment Share on other sites More sharing options...
ironwoods Posted July 12, 2006 Share Posted July 12, 2006 Personally I don't think that there wood be that much of a difference, if regular 3/4" Birch(7 ply)available @ yer local Menards is used. I bought a 4'x8' and had to make at least a dozen cuts, of which only 2 small voids were exposed, and approx. the size of a penny, if that. I seriously doubt that they wood have buzzed, if not exposed and filled. Void free, kind of reminds me of things like THX certified speaker wire. [:|] Quote Link to comment Share on other sites More sharing options...
Jay481985 Posted July 12, 2006 Share Posted July 12, 2006 most voidfree playwood is plugged and most people are non the wiser. Plugged means they just patched the burrs and such wide regular wood, you can actually see it if you look closely at the wood unless they just used voidfree plug free on the outermost layer. MDF is cheaper and really voidfree. It just isn't drop and screw friendly but acoustically better. Quote Link to comment Share on other sites More sharing options...
bluesboy Posted July 12, 2006 Share Posted July 12, 2006 That's right Jay. Plus you can you can get veneered MDF at a fraction of the cost of of marine grade plywood. It's foolish to use anything else for speaker cabinet construction. Quote Link to comment Share on other sites More sharing options...
jorjen Posted July 12, 2006 Share Posted July 12, 2006 Foolish? Kind of depends on the "speaker cabinet" you are constructing, would'nt you say? With the more complex projects that some of the folks on this forum get into, I do not think one can make a blanket statement such as this. Cornwall, Heresy, or any other plain old vanilla box design where 3/4" stock is acceptable throughout, yeah, sure I'll buy that comment, why not? La Scala, Belle, OK, maybe. Once again, 3/4" stock throughout. Klipschorn or Jubilee, uh, uh. I would not use MDF thinner than 3/4" on any speaker project I would consider building. On the Klipschorn, Jubilee and some of the other bass horns out there that folks are building for example, you will see wide usage of stock as thin as1/2" going into the construction of these projects. Is one going to use 1/2" MDF in these situations? I don't really know anyone that would or should. I know I would not. Like anything else, one should always use the best material available or that they can afford for the specific job at hand. There are plenty of circumstances in "speaker cabinet" construction where the use of MDF might also be deemed foolish. Quote Link to comment Share on other sites More sharing options...
WMcD Posted July 12, 2006 Share Posted July 12, 2006 I'm with Ironwoods. I doubt there is anything wrong with the better grade of ply at HD or the like. In theory. You do have to be a bit careful. I do go through the stack for the nicest looking. Further, it really is a sin how they set up the cantelever racks. Sometimes the set-up is not linear and they warp a kilobuck worth of ply with no apparent concern. There is a general suspicion out there that less than the best ply has some gross internal flaws. Maybe loose plys or big voids and these will lead to the completed cabinets having odd resonances or buzzes. OTOH, I've never read any report pointing to an example of any such acoustic problems. Some of the Chinese stuff I've seen at HD have obvious problems. You can see the loose ply which is flaking off. Also at the edges you can see internal plys which are overlapped and mushed flat. I will not use MDF. There are the mentioned construction issues. It is fragile and prone to water damage. In my case, the units have to be moved around. These are more localized to my situation. Others may think differently. MDF just offends me as an engineer. It annoys me that the cabinets in my kitchen are MDF. There is bulging from just splash from the sink. Grrr. The previous owner spent a lot of money on them but now I'm stuck with the problem. And then there are the typical bookshelves which sag. I rant. But will shut up. Gil Quote Link to comment Share on other sites More sharing options...
bluesboy Posted July 12, 2006 Share Posted July 12, 2006 Jorjen: I've built several Klipschorn bass bins using 1/2 inch mdf. How many have you built? Quote Link to comment Share on other sites More sharing options...
Jay481985 Posted July 12, 2006 Share Posted July 12, 2006 I'm with Ironwoods. I doubt there is anything wrong with the better grade of ply at HD or the like. In theory. You do have to be a bit careful. I do go through the stack for the nicest looking. Further, it really is a sin how they set up the cantelever racks. Sometimes the set-up is not linear and they warp a kilobuck worth of ply with no apparent concern. There is a general suspicion out there that less than the best ply has some gross internal flaws. Maybe loose plys or big voids and these will lead to the completed cabinets having odd resonances or buzzes. OTOH, I've never read any report pointing to an example of any such acoustic problems. Some of the Chinese stuff I've seen at HD have obvious problems. You can see the loose ply which is flaking off. Also at the edges you can see internal plys which are overlapped and mushed flat. I will not use MDF. There are the mentioned construction issues. It is fragile and prone to water damage. In my case, the units have to be moved around. These are more localized to my situation. Others may think differently. MDF just offends me as an engineer. It annoys me that the cabinets in my kitchen are MDF. There is bulging from just splash from the sink. Grrr. The previous owner spent a lot of money on them but now I'm stuck with the problem. And then there are the typical bookshelves which sag. I rant. But will shut up. Gil I did forget to mention that buying cheap plywood usually from china also use inferior glue. The Homedepot popular that is claimed furniture grade used a cheap glue that is now not holding and you can peel the layers off with a bit of proding. It was though 30 dollars a board..... Also 1/2 inch mdf is still quite strong, look at it this way yes mdf bends but so does any wood. They use 1/2 mdf in bookshelves which will have alot more weight (when you fill it up) than any speaker will ever bare load to. Heck the Ikea bookshelves that I have are 3/4 inch particle board (not even as high a grade as mdf and half the weight) and it is holding more than 300 pounds of books easily, and I even slid them across the floor to redo my room with the books still on it. MDF is not the bastard wood that everyone makes it out to be. Look at it this way, withough the mdf and particle board, all that shavings would be wasted and thrown away. Atleast they serve a purpose now and its not that bad a wood at all. Heck some mdf are even waterresistant if they use waterresistant glues. But its cheap and machines really well. Quote Link to comment Share on other sites More sharing options...
jorjen Posted July 12, 2006 Share Posted July 12, 2006 Jorjen: I've built several Klipschorn bass bins using 1/2 inch mdf. How many have you built? Well then, there you go. It MUST be "foolish" to use ANYTHING other than MDF in speaker cabinet construction. I stand corrected Sir. Please excuse me if I do not participate in this discussion any further. I am obviously woefully out of my depth. Quote Link to comment Share on other sites More sharing options...
filmboydoug Posted July 13, 2006 Author Share Posted July 13, 2006 I think both MDF and plywood have their place. I'm gonna do up a curved back speaker, so there is going to be a lot of router usage. MDF + router = dust that is 1000 times finer than talc that gets everywhere. Not happening. Quote Link to comment Share on other sites More sharing options...
Jay481985 Posted July 13, 2006 Share Posted July 13, 2006 use the router dust collector and a strong wet dry vac Quote Link to comment Share on other sites More sharing options...
JJkizak Posted July 13, 2006 Share Posted July 13, 2006 After viewing my patternmaker buddy constructing "pro" cabinets for clients with walnut, birch, and cherry 3/4" plywood at $400.00 per sheet I can honestly say that I have never seen a void. If you are going to build a K-horn why use cheap garbage? My personal opinion of MDF is rather gross and frightening and I would never consider using it for anything. JJK Quote Link to comment Share on other sites More sharing options...
Wrench722 Posted July 13, 2006 Share Posted July 13, 2006 Wood comes in a grade. Like A,B,C, and D. The words void free come from some Joe Blow that is looking for grade (A) wood. This is one of the places that I get very good wood. http://www.houstonhardwoods.com/species.php Quote Link to comment Share on other sites More sharing options...
BEC Posted July 13, 2006 Share Posted July 13, 2006 Wrench, I replied to your PM. I don't think the email notification of PMs is working. Bob Crites Quote Link to comment Share on other sites More sharing options...
Jay481985 Posted July 13, 2006 Share Posted July 13, 2006 After viewing my patternmaker buddy constructing "pro" cabinets for clients with walnut, birch, and cherry 3/4" plywood at $400.00 per sheet I can honestly say that I have never seen a void. If you are going to build a K-horn why use cheap garbage? My personal opinion of MDF is rather gross and frightening and I would never consider using it for anything. JJK speakers do not use real wood or solid wood due to the irregularities and voids that are associated with real wood. The resonance can be sporatic as the wood's density is not uniform hence all speakers that are made of wood are usually veneered or ply. What is so gross and frightening of MDF, might I ask? Also yes walnut, birch, cherry 3/4 inch plywood at $400 a sheet. Well I paid 22 dollars a sheet of MDF that was 49X97, so if the edge became damaged I can cut it off and still have the proper 48 X96. 400 dollars seems ridiculous a price to pay to make speakers....... Also I believe birch is the prefered plywood because it is cheap, uniform in density, and dense itself. Walnut has a lot of irregularity, just look at what the other forum member link provided note lots of voids and irregularity. cherry might be nice but I believe they call it a "softwood" which does not mean if its soft or hard but it means that it has open pores hence voids. Quote Link to comment Share on other sites More sharing options...
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