Is there a "Best" wood for speaker stands?

Discussion in 'Archived Threads 2001-2004' started by JeffTodd, Apr 10, 2002.

  1. JeffTodd

    JeffTodd Stunt Coordinator

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    I am gearing up to finally build my speaker stands and I was wondering if there was a "best" wood to assemble them out of. Would MDF would be better use than say a solid oak or maple? Is it going to make that much difference in the overall performance of the speaker? I would prefer the asthetics of real wood, but I just wanted some opinions first.

    Thanks.
     
  2. Greg Monfort

    Greg Monfort Supporting Actor

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    It can't be too rigid, so pick whatever hardwood has the highest MOE. The few stands I've built have been fabricated from either metal or marine grade plywood, though I would use Baltic Birch if I do any more.

    GM
     
  3. JeffTodd

    JeffTodd Stunt Coordinator

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    Thank you for the info Greg, but what is MOE? I assume it is a rating value for wood rigidity.

    Does anyone else have experience designing/building stands? Any other suggestions?
     
  4. jeff lam

    jeff lam Screenwriter

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    Jeff,
    I asked about DIY stands about two month ago and found the pics I needed. Brian Steeves has just one of the nicest DIY stands I have ever seen.
    Anyway, I am doing a very similar design using MDF for the stands and also birch for the side pannels. The MDF column will be hollow so I can fill them with sand too. Top and bottom base will also be MDF. The stands should be very heavy even without the sand. The birch is just added for looks. I'm planning them to look much like the stands in the picture in this link:
    http://www.hometheaterforum.com/htf...ighlight=stands
    This is the link to my previous post. Brian Steeves also has links to pics of his stands there as well. I believe he used MDF as well with veneer over it. This should give you plenty to feast on for a while.
    I would say to use MDF because it cheap, very heavy, and easy to route/work with.
    I'll be sure to post pics of my stands when I get them done.
     
  5. Hank Frankenberg

    Hank Frankenberg Cinematographer

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    For your central column(s), I'd use heavy pipe and fill it with sand. If you want a totally wood look, you could enclose the pipe with MDF and either paint it, veneer, it or laminate it with countertop laminate. OR you could make the column with MDF and fill it with sand. HEAVY is important.
     
  6. JeffTodd

    JeffTodd Stunt Coordinator

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    I am planning on using some 3in pipe if I can find it. I am going to run .5" all thread through the center of that to bolt everything together with. I will fill the column of the pipe with sand as suggested. The bases will be probably maple, .75" x 2 (a stair step effect) for the top and bottom.
     
  7. Greg Monfort

    Greg Monfort Supporting Actor

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    MOE = modulus of elasticity
    Yes, it's a rating in psi of the wood in both planes. A high MOE would be >1.0 million psi. For example, 3/4" MDF averages ~527k, and 3/4" marine grade ply, ~1.8m. Since rigidity increases with the cube of thickness, MDF must be ~1.125" thick to match the plywood's stiffness, though due to its higher density has a better damping factor (Q).
    When pieced together as an 'L' or 'T' angle it increases considerably based on panel size and height of the perpendicular piece.
    At one time I had the MOE of most woods, but somewhere along the line it's 'disappeared'. All I can find is their density, which doesn't do us much good.
    I wound up being in a hurry so had to cut my response short. Anyway, there's two approaches to designing speaker stands, the 'high road' or the 'low road'. [​IMG] I prefer the high and it appears Hank is sold on the low one.
    The high road is rigidity, ergo the low road is massive. With either way, the speaker/stand interface can be likened to constrained layer damping, where two highly dissimilar material properties are separated by a lossy layer. If they each resonate at two very different frequencies then the lossy layer acts as a common 'ground', effectively damping the system.
    So normally you either make it very rigid or very dense, with some silicone isolation feet between the two. The middle road is a dead end to good performance.
    If you have children and/or pets, then you're pretty much stuck with making it dense since you'll need to clamp them together so they can't easily be tipped over. This mass loads the speaker and may change its tonal balance for good or bad depending on its design/construction. I prefer portland cement for filling cavities, but sand seems to be preferred here. Just make sure its sterilized if it touches wood or according to others the microbes will eventually cause problems.
    GM
     
  8. JeffTodd

    JeffTodd Stunt Coordinator

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    You must forgive my ignorance Greg....I am but a lowly IT guy. All this stuff regarding the physical properties of materials and how they interact with the acoustical properties of sound just blows me away! What seemed like simply a process of slapping a couple of pieces of wood together to make something that will 1) Support a speaker and 2) Look decent in the living room has been transformed into quite a larger feat.

    Greg, I don't recall where I read it, but the person stated that maple was a good material to build stands out of. I am not too sure about the other details that he specified. I will search around for MOE values to see if I can find out where maple fits into everything.

    Thanks for the info.
     
  9. Greg Monfort

    Greg Monfort Supporting Actor

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    That's OK, I don't know what an 'IT' is, so you wouldn't have any trouble 'blowing me away' with your knowledge. Computers aren't my thing, audio is. I just gave the best answer I could. It's this attention to the physics of it all that partially makes high end gear expensive. Gotta pay for those big salaries and test gear, prototypes, etc..

    I didn't see your last response before posting, but since you want to couple the stand to the speaker, follow Hank's advice and fill a good sized pipe so that there's no air cavity to resonate, and build your stand design of choice around it, filling any cavities between the two, and making sure that the two can't rub together and squeak.

    In this scenario, all that matters about the wood is that it not have any loose knots or voids, and all the joints are solid. WRT pipe diameter/fill material, you want the finished stand to be at least several times heavier than the speaker.

    GM
     
  10. JeffTodd

    JeffTodd Stunt Coordinator

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    Greg,
    You may already know this, but I found it interesting...just a few MOE's:
    "The stiffness (MOE) of white oak is 1.78 million psi; white ash, 1.74; black ash, 1.60; green ash, 1.66; hard maple, 1.83." (http://www.woodweb.com/knowledge_bas...strengths.html)
    Also, Here is the link to my post I submitted a while back with my original design so you can see what I am attempting to do. Any comments or suggestions for improvement?
     
  11. Greg Monfort

    Greg Monfort Supporting Actor

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    Thanks for the link. I knew it was high, but it's been ages since I last had a use for them. The design looks nice. Since you're planning to tie them to the speaker I would go with a bigger tube to get more volume to add weight without resorting to the more expensive lead as the density of Hard Maple isn't very high (40lbs/ft^3).

    Using Portland cement (150lbs/ft^3) for filler, a 2" pipe 21" long will weigh ~5.72lbs + pipe, 3" = ~12.88+lbs, 4" = ~22.9+lbs, wood = ~9.9lbs, so even with the wood and 4" pipe, they're not very massive if I did the math right.

    How does this weight compare to the speakers?

    GM
     
  12. JeffTodd

    JeffTodd Stunt Coordinator

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    The speakers that I have presently are nothing big....just a pair of Aiwas that maybe weigh 15-20 lbs. In the future I am planning on building a pair of GR Research AV 1+ and although I do not know how heavy these speakers are I would bet they are heftier than my current speakers.

    And where can I get this cement that you mention? Is it readily available at places like Home Depot or Lowes?
     
  13. Greg Monfort

    Greg Monfort Supporting Actor

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    Yes, and while you're over there, check other types of mixes to see if there's any heavier. I'm not current on all the latest offerings.

    GM
     
  14. Pete Mazz

    Pete Mazz Supporting Actor

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  15. Greg Monfort

    Greg Monfort Supporting Actor

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    Great! Thanks! Can't have too much reference material.

    GM
     

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