Very casually testing 5-ply vs. baltic in the "handy panel" 2'x4' sheets. YMMV.
Maple vs. birch is only the veneer. It's got a core of something else, look at the pdf I posted above. Check out the yellow poplar here, pretty much the same thing without the veneer, bet it's pretty good especially for the price:
PureBond 23/32 in. x 4 ft. x 8 ft. Poplar Plywood-770579 at The Home Depot
The fed doc above list the densities (specific gravity) and stiffness (elastic modulus) of most common woods. Yellow poplar is pretty good.
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Baltic birch is about as heavy as mdf, most other plywoods are quite a bit lighter.
It's hard to believe you found anything good in Home Depot. I've never seen the PureBond stuff turbodawg is showing so I have no comment on it. The only plywood I've ever found there that I would consider using is Arauco brand, which they call "sanded pine". Arauco and baltic birch are the only two plywood products I've personally seen that are sufficiently void free to use for audio (and I've never seen BB at HD). There are other void free plywoods available from other sources but they might cost more.
No, no and no. None of that is void free. You can risk it if you want but if you get a rattle or buzz it's almost impossible to fix.
Arauco or baltic birch if you want plywood. Otherwise you can use any flat sheet product you want. The strength and stiffness determines how thick the panels need to be and/or how much bracing you need.
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thanks for your help, that's great information. So you would recommed the hardwood poplar ply? I think it came in 3/4.
I personally think void free is a bit overrated, I just fill the visable voids with wood glue and call it good. No buzzes so far.
A agree the araucoply (south american pine) seems to be a good and popular budget option. It's not available at my local HD. The stiffness and density is very comparable to the poplar.
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void free isn't a huge issue, I plan on glassing the inside.
Not sure where to get Arauco or BB, as the local lumber yard doesn't carry it. So HD or Lowe's are about my only options...
what exactly did you mean by any flat sheet product?
Not sure where to get Arauco or BB, as the local lumber yard doesn't carry it. So HD or Lowe's are about my only options...
what exactly did you mean by any flat sheet product?
Well, voids are usually inside the panel on one of the internal plys, the outer plys don't usually have voids. On the last build I did with 1/2" ply (3-ply, birch veneer poplar as above), I saw occasional voids about 1/8" and several inches long in the center ply, after making cuts. I simply put some wood glue in there and called it good, no buzzes. I would try the poplar, should be able to get a 4 cubes box out of one sheet with a nice slot port and bracing.
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The problem with voids is that they can be INSIDE where you can't see them or get at them. Voids on the outside faces certainly aren't a problem. Let's say you've got a knothole in the 3rd layer of your 5 layer plywood - right in the middle. Let's say the knot comes loose inside that knothole. Now you pound your box with some good old fashioned audio and your plywood turns into a rattle. How do you fix that? Sometimes it's possible to fix it, but most times it can be almost impossible to even find the problem, much less fix it. MOST of the time this isn't going to be a problem, but the one time that it is, it's going to be a BIG problem.
Arauco is hard to find these days since their factory burned down, but I've heard it's out there if you know where to look. Unfortunately I don't know where to look. Baltic birch is available from at least a dozen places in the Toronto/Kingston/Cambridge area. If you are not in that area, you local Home Hardware should be able to special order it for you. My very rural HH quoted me $60 a sheet for special order 3/4 BB last week, very reasonable. (For car audio I'd use 1/2 inch BB with good bracing - remember, BB is heavy like mdf.)
By any flat sheet product, I mean anything that fits your weight, strength and stiffness goals and won't cause rattles or buzzing in the long run. Stuff like particle board, mdf, plastic, glass, formica, aluminum, steel, etc. There are hundreds of sheet products, some cost more than others, some are stronger than others, some weigh more than others. If you use adequate bracing you can use just about whatever you want. Even osb. Osb might rattle or buzz (it didn't when I used it in the past though) but even if it does, it's $7 a sheet so who cares?
If you can't find arauco or BB at your local lumberyard, just ask them what they have that's void free.
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Play test tones to create buzz, then apply local pressure to find buzzing zone. Drill out to find void and fill with glue and then bondo. Worst case senario, entirely replace the panel. Assuming its actually a problem. I'm of the opinion that in a half decent quality plywood they are using enough glue to keep things from coming loose.
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I seriously doubt local pressure would work, you'd need the proper test tones and a mechanic's stethoscope to find the buzz. And assuming the knot is consuming most of the knothole volume (which it usually will) it's going to be almost impossible to get any glue in there, especially to get glue all the way around the knot to hold it in place. Even if you can do it you end up with a box with a bunch of drill holes in it's finish, so that has to be done again.
Like I said, this usually won't be a problem, but when it is you are going to wish you spent the extra money on void free material.
Like I said, this usually won't be a problem, but when it is you are going to wish you spent the extra money on void free material.
You can mail order quality Baltic Birch but it is not cheap.
I just ordered 5-30" X 30" X 18 mm sheets and it cost $42 for shipping, to Ohio.
They wanted about twice that for shipping 5 x 5's (60" X 60") but that is only 1/2 the price per square foot.
It is great stuff to work with.
Anyway, take a look here.
BALTIC BIRCH PLYWOOD, RUSSIAN, FINLAND, CRAFT PLYWOODS
Dave
All my speakers are less than 30" tall and 20" wide due to UPS prices.🙄
I just ordered 5-30" X 30" X 18 mm sheets and it cost $42 for shipping, to Ohio.
They wanted about twice that for shipping 5 x 5's (60" X 60") but that is only 1/2 the price per square foot.
It is great stuff to work with.
Anyway, take a look here.
BALTIC BIRCH PLYWOOD, RUSSIAN, FINLAND, CRAFT PLYWOODS
Dave
All my speakers are less than 30" tall and 20" wide due to UPS prices.🙄
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ICE SPL comp subs designed for extreme dBs at one frequency, could indeed gain that extra bit of bass gain in that region by doing absolutely everything to minimise turbulent losses.
Dare I say that correctly placed vanes, or flow optimise enclosure shape would gain more again.
Dare I say that correctly placed vanes, or flow optimise enclosure shape would gain more again.
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I don't see why not. I've already mentioned a bunch of times that a thick, polished steel or aluminum enclosure (for strength, rigidity and low Reynolds number) and bracing in the direction of airflow would be the way to go for max spl.
Or even an expansion sort of port, that's tuned to the desired frequency.
If it works at a certain frequency for motors, it must work for woofers too, right?
If it works at a certain frequency for motors, it must work for woofers too, right?
I have to go to the toilet....... while I laugh.
I suffer from depression, the kind where one wakes up and thinks 'Why did I wake again?' - suffered from it for the entire span of my time on this planet.
This last few days I have been very 'low' and your post has made me hoot with laughter AND put a smile on my face......
I thank you with all sincerity Sir for this.
I suffer from depression, the kind where one wakes up and thinks 'Why did I wake again?' - suffered from it for the entire span of my time on this planet.
This last few days I have been very 'low' and your post has made me hoot with laughter AND put a smile on my face......
I thank you with all sincerity Sir for this.
Hey, at least one of mine is home made (and designed).
That's DIY
Ring...ding...ding...ding
.
And over 130 dB at 150 Hz.
.
Glad it is at least worth a laugh
Dave
That's DIY
Ring...ding...ding...ding
.
And over 130 dB at 150 Hz.
.
Glad it is at least worth a laugh
Dave
A louder pipe would be a valve-less pulse jet..... 
And both ends could be disguised as ports.
I can supply a design if your interested 🙂
And both ends could be disguised as ports.
I can supply a design if your interested 🙂
That's in a car Basically anything that holds true in a sealed car cabin is not true for outdoor PA stuff.
Also, how is he quantifying .06 db gains from "armor all ' ing" the entire interior? Something so small HAS to be chalked up to fluctuations in measurements.
Also, how is he quantifying .06 db gains from "armor all ' ing" the entire interior? Something so small HAS to be chalked up to fluctuations in measurements.
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