MJL21193 said:
To clear up:
By design, I meant box construction design.
GM said:
Hi GM,
I'm in complete agreement with regard to the construction points.
Typical panel material (plywood, particle board, MDF) of the same thickness will have nearly identical resonance performance. It's the steps taken to attenuate resonance that have the biggest impact.
GM said:
Thanks. I get the urge to try something different now and then and the cheap way is with OSB or scraps of other "free" stuff I get.
I never did try cardboard and duct tape though.
July 'Hi Fi World' magazine has an interesting article on measuring resonnances in MDF, particle/chipboard and birch plywood cabinets with an accelerometer. The best affordable material they came up with was a combination of 18mm particle board glued to 6mm of MDF or 12mm particle board glued to 6mm MDF. This had better self damping and resistance to sound transmission than any of the other materials on their own.
Well done! Several years ago when I made my turntable plinth I also used MDF glued to particle board for the same reason. Nice for our hunches to be proved correct. Wonder if I glued some thin veneered MDF to the outside walls of my particle board speakers whether it would make a noticable improvement. (It would certainly look better than the current varnished particle board finish! )troystg said:
I've read volumes on this subject and have to believe 'laminates' of different materials likely best with Baltic Birch a 2nd. Alot of work to put together a laminate.
I'm not convinced tonal quality with inexpensive drivers would benefit to the point of investing in BB.
What puzzles me is hearing constant statements regarding price of OSB being comparable to MDF. Here in midwest USA OSB is 1/3 the cost of MDF - thats only reason I use it for experiments. $9 per sheet makes experimenting viable. Last I bought on sale for $7.89.
Can you use a router with this stuff without it chipping? All I've ever done is saw it.
I've never considered it for a permanent cab.
Bluto
I'm not convinced tonal quality with inexpensive drivers would benefit to the point of investing in BB.
What puzzles me is hearing constant statements regarding price of OSB being comparable to MDF. Here in midwest USA OSB is 1/3 the cost of MDF - thats only reason I use it for experiments. $9 per sheet makes experimenting viable. Last I bought on sale for $7.89.
Can you use a router with this stuff without it chipping? All I've ever done is saw it.
I've never considered it for a permanent cab.
Bluto
MJL21193 said:
Typical panel material (plywood, particle board, MDF) of the same thickness will have nearly identical resonance performance.
I never did try cardboard and duct tape though.
Greets!
Maybe in a tiny box, but with the average 3/4" (19 mm) MOEs of MDF's ~527 k psi Vs OSB's 580 k psi Vs BB/Apple/marine grade ply's ~1.8 m psi, MDF and OSB will have to be somewhat thicker to match the ply's since panel stiffness goes up at the cube of thickness in cabs big enough to need bracing.
I grew up in a simpler time of cardboard and Celotex corner cabs loaded with tiny magnet 'FR' drivers where glue was optional. They worked surprisingly well, though it would be many years before I learned why.
GM
GM said:
Hi GM,
Sorry I missed this.
Where did you get the MOE stats for these different materials? I've looked before, but couldn't find much. Interesting that BB ply is nearly 3.5 times stiffer than MDF.
No dispute that BB or marine grade plywood (Even formwork plywood) is much stiffer than the MDF or OSB and that overall it is a better material for box construction, but does this translate into an audible improvement?
A tiny box is what most of the projects we see here, other than the larger "horns". These horns have large panels that are fixed and unsupported at one edge (at the mouth) and have no real bracing. No amount of stiffness will completely tame the ringing these are bound to do.
Taking a larger box and using effective bracing will, for all intents, reduce this into several smaller boxes, therefore negating the advantage of superior stiffness.
Use of a CLD panel construction with two layers of these lesser materials would also be an option. OSB on the inside and MDF on the outside. A layer of lossy glue between (I used clear silicone caulking in a recent project - this sets to a firm rubber and is a very effective adhesive between sheets) and the reduction in resonance would be worth the effort. Economical too, as you use cheaper stock and save on interior bracing.
Bluto said:
Hi Bluto,
Here OSB is the same - about 1/3 the price of MDF. I recently bought 10 sheets for my amateur paint booth and the total was $69.90 plus tax. $6.99 per sheet as opposed to $22.99 for MDF.
That's now though, a few years back, OSB jumped up to $14.00 per sheet due to some shortage or such.
As for machining it, it chips easily so you would need to use sharp cutters. The upside is these chips will blend in - it is after all "chipboard"
A way to minimize the chipping might be to prefinish it with polyurethane first. This would firm up the surface a bit better.
I went to the lumber yard today to get the wood for my 2 tapped horns, and in talking to a few of the guys that worked there there is a product they sell called Advantech. It looks like a better OSB. It is made for flooring and they said you can leave it out in the rain and not have to worry about it swelling. Maby this means that cabinets made of this material will be less likely to swell at the joints from moisture / humidity. It bent less when I picked it up than both the OSB and MDF, although thats not exactly a scientific experiment. I paid about $20 per sheet. I went to the company's website http://huberwood.com/ and it is supposedly stronger and stiffer than common plywood. They make an industrial version that is supposed to be both stronger and stiffer than "specialty" plywood. The website has lots of charts and graphs available. Do you think their industrial stuff is really stronger than baltic birch ply?
i'm no expert, but so far i'm sold on OSB
i just so happen to have some BIB pairs, some are birch plywood ($40) and some are OSB ($13)
in my opinnion, the OSB sound better
this might be due to less resonance or a different density, i have no idea
as for routing and the like, OSB worked just as well as the plywood and i think it looks a bit better
i just so happen to have some BIB pairs, some are birch plywood ($40) and some are OSB ($13)
in my opinnion, the OSB sound better
this might be due to less resonance or a different density, i have no idea
as for routing and the like, OSB worked just as well as the plywood and i think it looks a bit better
MJL21193 said:
Greets!
No biggie, I'm just so inundated with email that unfortunately more often than not I'm in a 'last in, first out' mode and the rest fall off the bottom of the screen only to be 'found' during lulls in the 'deluge' as happened with this one.
Historically I've relied on tech data from Georgia-Pacific or similar via distributors that have been pretty good about giving me either ranges or a mean, though in recent years I've generally been able to Google such info, but it's normally buried in presentations such as this 399 page cure for insomnia: http://www.fpl.fs.fed.us/documnts/pdf2004/fpl_2004_wang004.pdf
Yeah, and I was being 'nice' using a relatively high MOE as MDF varies a lot depending on the manufacturer, plant, the batch, and even within a given plant, batch, or at least this was the case back when I last seriously researched such things, but that was almost 20 yrs ago now, so maybe it's automated enough now to only vary over a reasonable tolerance.
Quite the contrary, it's quite easy to push a large horn mouth's resonance above its passband with either increased thickness and/or bracing if you start with a stiff enough base material. What makes it tough to do is to start with a relatively weak material such as MDF since so much added thickness and/or bracing is required that what happens is you wind up massing it up so much you're 'chasing your tail' to the point where you might as well just cast it in reinforced concrete if it's a LF horn, high excursion sub woofer or similar. This is also true of typical MDF speaker cabs large enough to need bracing if you truly want to get it out of its passband. HF horns and small speakers with a > ~250 - 500 Hz Fb (depending on material, etc.) OTOH benefit from using 'weak' and/or massive materials since it's easier to push the horn's/speaker's resonance below its passband.
Yes, CLD can be the 'best of both worlds', but tends to get too time consuming/costly for the typical DIYer when done right. WRT to your proposed composite, you ideally want to maximize the impedance mis-match between panel materials, so BB ply with the most crumbly particleboard you can find in sheet form or with thin aluminum sheet if moving in the other direction are good choices.
Anyway, yes, there can be both measurable and audible differences in these choices, but even if there weren't and even ignoring MDF's health issues, stiffer base material = less weight, woodworking, damping for a given bulk and greater electro-mechanical acoustical efficiency potential, so this is always going to be my choice/recommendation for any cab meant for a < ~0.7 Qts driver in a < ~500 Hz BW, so I guess we'll have to agree to disagree as to what's the best bang/buck overall for the vast majority of DIY cab designs.
GM
This got interesting.
All the talk had always been about sonics and why I stated I'd came to conclusion laminates likely best with BB a 2nd.
I simply had chosen OSB as I'd started a shed project way back that local zoning didn't approve so had a bunch of it on hand with no use of and it hadn't cost me much.
Surprised to see others using it as well with good results. I try something, listen a couple weeks, tear it down, recut and try something else til it's fit for the burn pile.
In another thread I'm seeing guys having good results actually putting a finish on the stuff.
There may actually be something to this stuff.
I was also happy to see guys having luck routering it which I'd been fearful of trying.
Bluto
All the talk had always been about sonics and why I stated I'd came to conclusion laminates likely best with BB a 2nd.
I simply had chosen OSB as I'd started a shed project way back that local zoning didn't approve so had a bunch of it on hand with no use of and it hadn't cost me much.
Surprised to see others using it as well with good results. I try something, listen a couple weeks, tear it down, recut and try something else til it's fit for the burn pile.
In another thread I'm seeing guys having good results actually putting a finish on the stuff.
There may actually be something to this stuff.
I was also happy to see guys having luck routering it which I'd been fearful of trying.
Bluto
I just got back from the local Lowe's to check on cabinet materials for a project. I looked at the Advantech OSB. And it looks like a very impressive material for the money. It is much stiffer and more dense than standard OSB. In fact, it is a lot heavier and stiffer than all of the standard grade plywoods of equal thickness. I also noticed that it has a smoother surface finish than standard OSB.
I believe that it is just made with a little more wood and resin and compressed at a higher pressure than standard OSB. The resin seems to be more impregated throughout the material. And it has a little bit more of a plastic quality than standard OSB.
The cabinet is a bass module so stiffness is the most important thing to me and a double thickness of this material in 23/32 thickness might just be the right thing. On sale at only 17.95 per sheet. I don't think that it will route that well but I will use a piece of MDF for the front plate and keep the routing of the OSB to a minimum on the back sides.
When I lift up the edge of a sheet and rap on it it seems more dead than particle board and more stiff than MDF, particle board or plywood.
I believe that it is just made with a little more wood and resin and compressed at a higher pressure than standard OSB. The resin seems to be more impregated throughout the material. And it has a little bit more of a plastic quality than standard OSB.
The cabinet is a bass module so stiffness is the most important thing to me and a double thickness of this material in 23/32 thickness might just be the right thing. On sale at only 17.95 per sheet. I don't think that it will route that well but I will use a piece of MDF for the front plate and keep the routing of the OSB to a minimum on the back sides.
When I lift up the edge of a sheet and rap on it it seems more dead than particle board and more stiff than MDF, particle board or plywood.
Prototyped a bunch of stuff with OSB recently. Looks pretty ghetto, even done neatly, and given a coat of floor paint looks frankly somewhat worse. I don't really care how stuff looks so long as it sounds good.
The problem with OSB is getting the glue into the end grain, it's not very strong in that respect, so the little wood chippings tear off. As a result, I blew the side off a high-powered subwoofer box, was not the glue that failed, was the end grain wood, and also on the other subwoofer box it ripped the speaker screws out of the baffle during its first show, so will need to replace with tee nuts.
What I'm now working on with these prototypes is reinforcing the box structures from the outside with wood or steel batons.
The boxes themselves sound great, in my opinion slightly better than baltic birch.
Rapping the box with the knuckle, it's not at very dead, produces a pleasant woody knocking sound, different pitches for each panel, so I suspect that there is probably a euphonic resonance effect going on. For playback gear, which is what this stuff is intended for (rather than critical monitoring) in many ways with resonances, it's more important that if they are there, they are pleasant sounding rather than not there at all.
The other big benefit of OSB is that it's light, in the wood shop that's what made me jump in & give it a go, the sheets of ply were over twice as heavy. With biggish PA boxes with quite a few internal baffles, this makes a big difference to the overall weight. What would have been a two-man lift is now just handleable by one person.
OSB, though, isn't a tough material. I wouldn't want to tour these prototype cabs I've got, so looks like I'll either be sandwiching the stuff under 5mm of birch ply, or just using standard high grade ply for everything.
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