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Minimum thickness for speaker cab construction

#25
OK help me out here. What makes OSB inferior acoustically to regular plywood? The principals in their respective construction are very similar. It seems to me that oriented strand would be less resonant than regular ply...aside from using it on the baffle (which I wouldn't), what makes it so poor for speaker building?
From a construction standpoint, I can see how regular ply is a little stronger, especially on the edges, but I'm not concerned by that. I can adequately brace the box, so that's not an issue either.
Of course, it sounds like I'm asking you to tell me what I want to hear, but so far I'm not all that convinced that it's bad to use this stuff.:D
C7
 
#26
I'll stick up for OSB. (although I haven't used it for speaker cabs)
It's no worst than most the plywood you buy at the depot.
Because it's cheap - you don't feel bad about tossing out something made from it. :-)
Kidding aside - it's used all over the place in construction. From floor beams to roof sheathing. It's strong.
It's no more resonant than plywood. It's a little heavier. (around here)
Predrill, use polyurethane glue, brace and you'll be OK.
The price of the wood is typically the least of the costs in DIY.
 
#29
Proper bracing eliminates resonance, no matter what the material.

If it resonates, it is not properly braced.

Yes, you can brace OSB so it doesn't buzz. As noted above, a 3 pound sledge or a 200 pound roadie can easily inflict damage on an OSB cab.

I cannot understand why one would do ALL that work and use crap materials or cheap drivers.
 
#30
bgavin said:
I cannot understand why one would do ALL that work and use crap materials or cheap drivers.
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If I went out and bought the OSB to build a cab I'd be a chump, and I know it. But I have 4 full sheets' worth of it sitting right behind me in 4'x 4' sections, doing nothing but taking up space and pissing off my wife. If she's gonna bitch about something, it might as well be another bass cab. :D My roadie is a 200lb me, and I don't hit my cabs with sledgehammers.:D
As for the driver, I'm going to use a brand new 12" Delta LF.:D

Screw it, I'm going to make the cab. If it really sounds as bad as people think it might, whatever. I'll use it for firewood, just like I would if I didn't build something out of it. If it sounds awesome, righteous.
C7
 
#32
Crockettnj said:
i didnt read too many comments about how it would sound. seems to be a major criticism of the osb is that durability.

build it and see.
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Durability isn't a concern of mine. I could build it out of 1/4" balsa, and I would never break it. I baby my gear, and it's going to be a combo that will be in my basement and taken to acoustic jams and open stages around town occasionally. If I'm dumb enough to drop it or hit it really hard with a hammer, I deserve to have a broken cab. :D
What I was looking to hear was "yeah, OSB will likely give you a resonance in your upper mids due to the..." type of stuff.
Since I didn't hear any of that, I'm going to build it.:p
C7
 
#33
Crescent Seven said:
[

Screw it, I'm going to make the cab. If it really sounds as bad as people think it might, whatever.

I dont think osb will make that great of a cab. But like you said, you already own the material so the only thing you've got to loose is a little time and sweat, and if it does sound like s#*t you can pull the driver and give it the drop test off you roof for some laughs! If it turns out you love the sound,bonus.
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#34
To summarize what I have learned from various threads and posts, the panels have two functional purposes:

1. Hold together

2. Not vibrate

Neither of these requires thick panels. Holding together is done with cleats, similar to double butted tubing on fancy bikes. Not vibrating is done with bracing.

My only concern is whether OSB holds together with regular glue, which is just something I have no knowledge of.

From my own experience, I would say that one's first cab is always an experiment, and you might as well experiment with the OSB. Since it is free, you can go through a couple design cycles before committing to a piece of more expensive material. Or, hide it under tolex.
 
#35
fdeck said:
To summarize what I have learned from various threads and posts, the panels have two functional purposes:

1. Hold together

2. Not vibrate

Neither of these requires thick panels. Holding together is done with cleats, similar to double butted tubing on fancy bikes. Not vibrating is done with bracing.

My only concern is whether OSB holds together with regular glue, which is just something I have no knowledge of.

From my own experience, I would say that one's first cab is always an experiment, and you might as well experiment with the OSB. Since it is free, you can go through a couple design cycles before committing to a piece of more expensive material. Or, hide it under tolex.
Click to expand...
For vocals/guitar I would agree with using 1/2" but for Bass I would always follow the 3/4" route, I once used 5/8" for Bass guitar and the difference was quite amazing, the amp even moved around on top of the cab, I never encountered this problem with cabs of the same dimensions using 3/4" ply.
I do agree with experimenting, the satisfaction gained from building and developing something that sounds good is imeasureable (you then realise how much cash you can save).
 
#37
jellisii said:
I assume that the goop they use to hold the strands together fills in any voids that might be caused by the layering process? I only ask because if that's *not* the case, the cab will probably buzz badly.
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It doesn't, and that's part of the problem. OSB is used in building where flexion strength isn't required, in walls and roofs where it isn't layed on the horizontal. It isn't used in floors, because it would bounce (a special product resembling OSB is used for floors, it has 30% higher density). OSB stands for Oriented Strand Board, as the wood chips its made of are oriented in the same direction, unlike plywood, which has layers of grain oriented at 90 degree angles. The result is a product that doesn't have the stiffness of plywood. Combined with its high degree of porosity OSB lacks the properties required for a non-resonant box. Every watt of power that ends up flexing the cabinet walls is a watt that doesn't end up as sound.
 
#38
Solely on the thickness issue, and neglecting whether OSB is the right material for the job, one could do an experiment. Build the cab with the 1/2" OSB and minimal bracing. Measure the response curve using my program. Now add an extra thickness of OSB and test again. Or, add internal braces and test again.

Right up the street from me is the USDA Forest Products Laboratory. Maybe they should start doing research on bass cabs. More importantly, they should hire me as a top scientist to manage the project, and outfit the lab with the best bass gear around.
 
#39
fdeck said:
. Maybe they should start doing research on bass cabs.
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It's already been done, more than once, and the results published, in sources ranging from Speaker Builder and AudioXpress magazines to the Journal of the AES in the US, as well as European sources. Where weight is not an issue 1" MDF is the preferred material, where low weight is required 1/2" plywood cross-braced every 6 to 8 inches works best. Pound for pound cross-bracing is four times as effective as added mass in limiting panel flex, but costs twice as much to produce when labor costs are factored in. For that reason cheap cabs will often weigh a lot more than very high end cabs. Where cost is no object a honeycomb composite matrix gives the best strength to weight ratio; it's why JBL Vertecs are quite light and cost upwards of $10k each.
 
#40
You have it there just make it. Like you said, I wouldnt go out and buy the stuff to make a cabinet, but it's there sooooo......Alot of vintage cabinets used press-board at one point. That is just a bunch sawdust glued together. When it gets wet, you might as well throw it away. If it doesnt fall apart first. Others have used 1/2" pine with 1/8" fingerjoints. Fender did this alot. Vox used 13 and 7 ply Baltic birch and just plywood at one period. Then some companys like Legend, used solid slabs of Oak and Walnut.


We use true 13-ply Baltic Birch or this other stuff that has 6-plys of Baltic with a composite filler in the middle. The latter actually is heavier duty and sounds alot better. It doesnt absorb the sound. 3/4" is the min we use for the top/bottom and sides, and 1" for the baffle and back.

You also need to consider what joints you are going to use to hold this thing together! We only use glued finger joints. The type of joints really determines the "bracing" that you need. If you use a simple butt-joint, then you will need extra bracing in the corners. Remember use plenty of glue.

Make sure to fill in all voids and then sand it realllll good.

If you dont like the sound of the cabinet when you get it done, try throwing some insulation in it. Just staple it to the back and or the sides.

Just take your time.
 

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