I don't "subscribe" myself; but it is a lot tougher if it has to be moved often. Also it is a locally made product not imported and cheaper than the local Hoop pine and it doesn't need to be veneered etc.
I've never used OSB for speaker boxes but when stained and polished I like the look.
I think I'm in the "Use what I can afford" camp of box building and I don't think it really matters much anymore what I build monkey coffins from.
I can name 20 or 30 things that you need to do that are more important than deciding what you build your cabinets from.
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OT: I love working with MDF. It's like cutting butter. Plywood is like cutting real wood.
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This where we part company. Because of my work, this is the last product I want to see in my home.
Amen brother. I used to cruise the garage/yard sales to find those 'furniture' items hat could be reconditioned into 'speakers'
I work with recycled paper and cardboard, tongue depressors and bamboo barbecue sticks. My current build involves a lot of bracing, as I like large speakers that can be lifted with one hand. Thinking a lot about sawdust and shredded paper for channeling vibration away from the speaker diaphragm. Sheer weight is not the answer for me. ToS
Re the weight, MDF does come in a range of grades, the product that we used in commercial millwork trade is 48lb per cubic foot, so a 3/4” 4x8 ft sheet = 96lbs. At 35mm, that would be 177lb.
I appreciate all the input but it just reinforces my opinion. Every time the subject is discussed all the different favourite materials are presented (along with their perceived advantages). Eventually the thread moves on to laminates and exotic materials that are often too expensive, unavailable locally, or require more than basic home workshop tools to fabricate with. My own "ideal" drawn from reading hundreds of other posts is for a sandwich of ply and MDF using a layer of polysulphide mastic adhesive as a bonding layer but since I live in my own impoverished world choosing the cheapest material will have to be the way to go. Weight is not an issue in my case. I can get the sheet cut into smaller pieces at the source. I'm not interested in portability. I have used many different grades of ply as a boat builder in the past and most of the affordable ply where I live now isn't suitable for anything more than shuttering concrete. I may well back off a little from 35mm to 28mm and spend some extra time with bracing. The point made above about Brittany and its humidity is a good one. I have a constant battle stopping my tools from going rusty. My speaker boxes will need a healthy coat of epoxy inside and out whatever they are made of. Years ago I made a simple enclosure for a guitar practice amp out of scrap rubbish chipboard (particle board). After a single generous coat of epoxy it was never used. Left in a garden shed for 20 years+ it didn't suffer at all.
One more thing. The warnings about MDF dust should be more well known. Similarly dust from teak and mahogany, but then few of you will be using these for monkey coffins.
One more thing. The warnings about MDF dust should be more well known. Similarly dust from teak and mahogany, but then few of you will be using these for monkey coffins.
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If you don't do so already, then coat your tools with Camelia Oil. It is a non-toxic vegetable oil that oxidises on contact with air to become waterproof. A tiny amount will o a long way. Works on all metals, and indispensable in a maritime climate. ToS
Yes the problem is people discussing their opinions about cabinet construction and readers without a mechanical/acoustical engineering background having difficulties distinguishing between that which involves genuine engineering and that which is an old wives tale. This is exacerbated by sound radiation from the cabinet being difficult to measure in the presence of the sound from the drivers leading to a low level of hard evidence circulating among DIY speaker folk.
I have been pondering putting up something that covers the basic engineering of a speaker cabinet for a while but it would be a significant amount of effort if it is to include a significant amount of hard evidence which I think is required to be persuasive. I have no illusions about the lack of effectiveness of posts like mine above and the small number of similar ones mainly from people in the industry. Posts like yours are encouraging though and may help overcome my inertia.
On a related note is anyone aware of anything out there that covers the sound radiation from cabinets from an engineering perspective? I am aware of the decades old BBC publications which include measurements for thick vs thin wall cabinets, audibility thresholds for cabinet radiation, effects of damping, and some other useful stuff. KEF have come out with one or two relevant examples based around their products. I am aware of one or two academic papers that may have relevance to one or two particular aspects like constrained layer damping, measurement approaches but nothing on the primary topic of the physics of a quiet speaker cabinet.
Does anyone else with a relevant background (physics of vibration, engineering simulations, laser vibrometer,...) have a possible interest in jointly working on the topic?
You are far better on wood-plates than we here in France. France is gifted with food but not wood-plates. We have oak, some beech, cherry and ordinary quality pine. None of the good Douglas fir and other types that are known from northern territories. Therefore, we do normally not build houses in wood but from bricks, concrete or stones. Wooden plates here are often MDF, chip-wood or mediocre ply-wood. I have seen ply-wood plates of "exotic" wood (meranti) but still a low-density product.
Come to France for the food, not to buy wooden plates. Also the price of wood here, many of you will not appreciate.
Come to France for the food, not to buy wooden plates. Also the price of wood here, many of you will not appreciate.
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No background or info to offer, but a Sticky topic would be very nice! Especially the basics. And if possible some guidelines about panel thickness or a simple method to calculate problem area. Some rules of thumb would be nice. How to make a cheap vibrometer. I do hope you get cooperation.
Whenever in doubt, use middle-of-the-road approach. Enclosures built and braced of typically available materials, are well enough to not present a problem. I use a thicker board for the baffle and thinner ones for the rest of the enclosure.
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I have thought about similar things and concluded that neither FEA simulations or laser vibrometers are much good in quantifying the audibility of the problem.
Instead, my recommendation would be to build a enclosure that has an enclosed driver on the inside. Only sound leaking through as panel vibrations will then be measured.
Now, keep the outer surface area equal, but add well known techniques and measure what changes:
- Bracing
- Increased panel thickness
- Dampening sheets
- Constrained layer dampening
- Driver decoupling etc.
This should give reduction level in dB, a FR curve that is easy to read for most people
It can be used to evaluate the audibility of a problem as you can change the level of panel radiated sound with adjusting the volume on the internal driver and use a ABX software to tell you if you cant detect the panel vibrations. Of course, this should be evaluated while also playing signal through a normal speaker to allow masking effects come into play.
Best, Fredrik
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That's about the density of the colored MDF (Valchromat) I mostly use now. Rather heavy but it doesn't feel mushy like cheap mdf and it holds an edge better.
The better mdf panels are also from the E1 category, with extremely reduced formaldehyde emissions. Not to say the dust is fine to breathe (far from it) but they're less toxic than the cheap stuff.
I like baltic birch because of it's work-ability, and dimensional stability.
I can do much more precise work with it than anything else I've tried.
It's simply a pleasure to work with imo.
MDF cuts and mills well, but doesn't hold screws well, or glue as well.
I don't care much about resonances etc.
Bracing, measuring, and bracing again, solves resonances ime.
For me, the void free aspect of BB is much more about good work-ability, than vibrations. Not sure i even believe the void free vibration claims.
Weight matters, but there's 12, 15, & 18mm BB to choose from to help with that.
I can do much more precise work with it than anything else I've tried.
It's simply a pleasure to work with imo.
MDF cuts and mills well, but doesn't hold screws well, or glue as well.
I don't care much about resonances etc.
Bracing, measuring, and bracing again, solves resonances ime.
For me, the void free aspect of BB is much more about good work-ability, than vibrations. Not sure i even believe the void free vibration claims.
Weight matters, but there's 12, 15, & 18mm BB to choose from to help with that.
Engineers or old wives...that's it? What about pro sound? What they build and use has to be optimized for durability and performance. This is not the seventies, when loud was all PA speakers had to be. No void plywood is available at the lumberyard. Doesn't have to come from Baltavia.
I wish we had that stuff more accessible over here. Black Valchromat looks great with a light finish applied.
Later,
Wolf
Is a combination of 2 materials better vs a only MDF or plywood?
For example, have the inner carcass of the speaker box made out of 1/2" MDF and then have another layer of 1/2" ply over it? Or too much ado over nothing much?
Of course, brace the box properly in any case.
For example, have the inner carcass of the speaker box made out of 1/2" MDF and then have another layer of 1/2" ply over it? Or too much ado over nothing much?
Of course, brace the box properly in any case.
Its just my belt and braces unproven theory. Ply and MDF having different densities and characteristics in the acoustic environment. I would stick one to the other with a non rigid goo. Anything getting past that lot deserves its freedom. I have used acoustic soundproofing in marine engine rooms that also used an unusual combination. Panels comprising high density open cell foam and low density foam separated by a thin layer of heavily loaded polymer (or lead foil) was stuck on to steel bulkheads. It was something like 60% effective at damping noise from getting past into the adjoining rooms. Using only one of the layers alone was pretty much useless.
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