Ran across some MDF sheet at my local Meanards yesterday and here all this time I had been thinking that MDF is the same thing as what I've called particle board.
Obviously i had it wrong.
Particle board is the material used for flooring underlayment, roof sheathing etc and comes in 2 flavors --
medium density (common) and high density (cabinet grade that weighs a TON).
I can see now that MDF is a different animal.
Smoother, sort of a brown color, somewhat lighter -- looks a little like a type of "masonite".
So --
MDF is superior to particle board? Why?
Is particle board even used in speaker enclosures?
Obviously i had it wrong.
Particle board is the material used for flooring underlayment, roof sheathing etc and comes in 2 flavors --
medium density (common) and high density (cabinet grade that weighs a TON).
I can see now that MDF is a different animal.
Smoother, sort of a brown color, somewhat lighter -- looks a little like a type of "masonite".
So --
MDF is superior to particle board? Why?
Is particle board even used in speaker enclosures?
Yes, it's a lot like Masonite, just sawdust held together with glue.
It is denser and less resonant than particle board (more correctly called Oriented Strand Board, I think). You don't see too many people using OSB, as it's not very smooth on the surface and therefore hard to finish, veneer, etc, and tends to split out in the fine cuts like joints and speaker-mounting chamfers. Most people who want to use a more wood-like material go to a birch plywood, the better grades of which have numerous thin laminations.
--Buckapound.
It is denser and less resonant than particle board (more correctly called Oriented Strand Board, I think). You don't see too many people using OSB, as it's not very smooth on the surface and therefore hard to finish, veneer, etc, and tends to split out in the fine cuts like joints and speaker-mounting chamfers. Most people who want to use a more wood-like material go to a birch plywood, the better grades of which have numerous thin laminations.
--Buckapound.
Yes sure:
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But if you want to paint particle board, be prepared to spend some serious extra time and money to get a smooth finish (especially when you're using butt joints). MDF is less problematic. For veneering particle board is just fine.
Best, Markus
No, this is OSB (has a very uneven surface):
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Particle board:
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MDF:
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Best, Markus
Ok thanks.
I have used high density particle board before, which machines much better than regular, but it weighs as much as concrete.
I can see why MDF is the popular choice, I bought a 2 x 4 sheet yesterday -- very nice.
I'm anxious to get started on my project.
I have used high density particle board before, which machines much better than regular, but it weighs as much as concrete.
I can see why MDF is the popular choice, I bought a 2 x 4 sheet yesterday -- very nice.
I'm anxious to get started on my project.
Particle Board (called Chipboard in the UK) is indeed used foor flooring etc as it is strong enough and cheap! Easy to cut.
MDF takes the edge off tools quickly and produces nasty dust.
I fancy that real MDF only became available in the last 20 years or so (but I am getting old!) as I have several sorts of speaker cabinets (B&W DM220 etc) all made out of vaneered chipboard.
As stated, they break easily at machined edges and do not "thud" like a good MDF box.
MDF takes the edge off tools quickly and produces nasty dust.
I fancy that real MDF only became available in the last 20 years or so (but I am getting old!) as I have several sorts of speaker cabinets (B&W DM220 etc) all made out of vaneered chipboard.
As stated, they break easily at machined edges and do not "thud" like a good MDF box.
As far as sonics go, high density particle board is probably better than than MDF. To get around finishing issues Peter from WD has been advocating an MDF/paricle board sandwich.
IMO, neither is as good as a good multiply like Baltic Birch (so much so that we'll happily pay $50 a sheet for BB, even when all the MDF we'd need is free)
dave
IMO, neither is as good as a good multiply like Baltic Birch (so much so that we'll happily pay $50 a sheet for BB, even when all the MDF we'd need is free)
dave
That "thud" is actually an indication of one of the big problems with MDF... the resulting sound with a knuckle rap on a good box should be much higher in frequency and have a higher Q. I colourfully describe the problem with MDF as its tendency to ouze out a low level time-delayed and blenderized version of what is inside the box reducing the potential downward dynamic range of the speaker system.
dave
If you don't mind the side track. What thickness of BB plywood is preferred, how many plys?
I think to a great degree that'd be application dependent - i.e. a 3" wide-band driver for near field computer use could probably get by quite nicely with 9-ply 12mm (nominal 1/2") while a 15" HT sub woofer definitely benefits from 2 layers of 18mm - and lots of bracing.
Most of our projects for the past few years have been for 6" or smaller FR drivers (Fostex, CSS, Mark Audio, etc.) and I've been quite happy with the results from combination of 15mm for the cases, and 18mm for baffles for rebated drivers.
Depending on the application we use 12, 15, or 18 MM BB (9/11/13 plies respectively). Occassionally, sufficient energy is generated (ie the sealed SDX7 in Tysen), and we will end up laminating another layer of material (sides of Tysen ended up as 2x12mm).
So that we can economize by buying lifts of material we try to standardize on 15mm, and add more or altered bracing when we encounter a resonance.
dave
So that we can economize by buying lifts of material we try to standardize on 15mm, and add more or altered bracing when we encounter a resonance.
dave
I build quick n dirty projects out of OSB. It's super cheap! I built a sub out of it, and when I sometimes sit on the box I'm always suprised how solid it feels. I always expect wood stuff to have a slightly mooshy or springy feel, but that sub of OSB and coated with poly feels like it's made of rock. Also, the stuff I buy has a smooth side and a rough side. I have routered it for countersinking a driver and it worked just fine. It will flake, but a couple coats of poly will keep that down.
I used MDF, but it's so soft. I ding it up when I'm working with it, a little pressure on a corner or edge makes the stuff mush up pretty bad, in my experience.
I use nice ply when I want it to look good, and OSB when it doesn't matter.
I used MDF, but it's so soft. I ding it up when I'm working with it, a little pressure on a corner or edge makes the stuff mush up pretty bad, in my experience.
I use nice ply when I want it to look good, and OSB when it doesn't matter.
thud?
interesting... must have to do with construction techniques... I don't get a "thud" with mdf... more of a higher pitched "thwack" or "click". Don't hear much of the "oozing" effect either... maybe due to the type of box (sealed vs. ducted ?) and or the overall system Q. But i tend to brace like mad internally, no matter what the material, to limit the unsupported regions maximally.
Unless Im using sonotubes, that is...
John L.
interesting... must have to do with construction techniques... I don't get a "thud" with mdf... more of a higher pitched "thwack" or "click". Don't hear much of the "oozing" effect either... maybe due to the type of box (sealed vs. ducted ?) and or the overall system Q. But i tend to brace like mad internally, no matter what the material, to limit the unsupported regions maximally.
Unless Im using sonotubes, that is...
John L.
MDF like all things can be cheap and nasty or good quality. There are huge differences.
Another good material is HMR Board. This is highly moisture resistance. Edge on it looks green, that is the colour of the glue. It can be obtained in both MDF and chip board. If you want it at a better price go to a company that makes good quality kitchen bench tops.
Terry
Another good material is HMR Board. This is highly moisture resistance. Edge on it looks green, that is the colour of the glue. It can be obtained in both MDF and chip board. If you want it at a better price go to a company that makes good quality kitchen bench tops.
Terry
The bracing.... since MDF is not as stiff you need more of them. Also better quality MDF (ie HDF) also helps.
dave
Newb question here...
If a material like BB ply is stiffer than MDF, wouldn't that make the resonant frequencies higher and more prominent? If this is true, would MDF be better for smaller enclosures housing mid range and full range drivers, and BB ply better for larger enclosures for woofers/subs?
Most of my DIY stuff has been subs and I've always used MDF, though a couple of times I used "straw board" which is basically particle board made from straw - smells like an old barn while cutting.
If a material like BB ply is stiffer than MDF, wouldn't that make the resonant frequencies higher and more prominent? If this is true, would MDF be better for smaller enclosures housing mid range and full range drivers, and BB ply better for larger enclosures for woofers/subs?
Most of my DIY stuff has been subs and I've always used MDF, though a couple of times I used "straw board" which is basically particle board made from straw - smells like an old barn while cutting.
Resonant frequency will be raised, yes, but it may or may not increase in amplitude. However, higher frequencies are easier damped.
Yes it makes resonant frequency higher. That is a very good thing -- as long it is part of the whole build strategy). I have yet to condense below into a comprehensive article so you'll need to wade thru this thread.
http://www.diyaudio.com/forums/cons...s-build-speakers-out.html?highlight=materials
Reading this post 1st will put alot of the back & forth into perspective
http://www.diyaudio.com/forums/mult...rising-geddes-loudspeaker-27.html#post1494425
dave
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