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I want to know what difference fellow members find when the subbox is built in mdf of plywood.
 

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Re: mdf or plywood?

I want to know what difference fellow members find when the subbox is built in mdf of plywood.
MDF is hard to work with and heavy. A properly designed and braced cabinet doesn't have to be heavy. I use plywood exclusively, and 1/2" at that, and my cabs do not vibrate. But bracing entails higher labor costs, so manufacturers prefer to use heavy materials instead, and MDF especially, as it's both heavy and cheap. One benefit of DIY is that you can do a better job on the cabinet and not be concerned about the labor cost.
 

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Re: mdf or plywood?

Like Bill said, MDF for test boxen because it is cheap, 7 ply birch (or better yet, fir) for finished goods.

Best,
Mark
 

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Re: mdf or plywood?

Would you guys still use 1/2" material if you were building an LLT? Say something 4' X 4' X 2' for example?
I'd never build a reflex box that large, in the same space a folded horn would work far better, but in any event I'd still use 1/2 plywood. Pound for pound cross-bracing is at least four times more effective than mass in controlling vibration.
 

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Re: mdf or plywood?

I'd never build a reflex box that large, in the same space a folded horn would work far better, but in any event I'd still use 1/2 plywood. Pound for pound cross-bracing is at least four times more effective than mass in controlling vibration.
Awesome. That's how I feel about things as well, and I was wondering how people would perceive my using 1/2" bracing throughout the box. I'd rather build smarter and lighter than just add mass because I can. Though I'm also a firm believer in mass in it's own applications, in this case I'd rather shave a couple dozen pounds and just spend more time designing a bit better. :bigsmile:
 

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Re: mdf or plywood?

Would you guys still use 1/2" material if you were building an LLT? Say something 4' X 4' X 2' for example?
By LLT you mean EBS right?

I usually stick with 3/4" and add bracing where needed. A box that big I would normally do a double baffle as I usually like to flush mount the drivers. I've found with ply you don't need much bracing since it is structurally superior to MDF to begin with.

Best,
Mark
 

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Re: mdf or plywood?

By LLT you mean EBS right?

I usually stick with 3/4" and add bracing where needed. A box that big I would normally do a double baffle as I usually like to flush mount the drivers. I've found with ply you don't need much bracing since it is structurally superior to MDF to begin with.

Best,
Mark
I have no idea what an EBS is.

While Ply is structurally superior, you need bracing to keep the large panels from resonating. Each brace effectively cuts a large resonating panel into smaller panels that wont resonate (hopefully) in a frequency that makes a difference to your sub.
 

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Re: mdf or plywood?

It is very rare for panel resonances to be an issue with subwoofers that have an Fc (crossover point) at or below 100Hz. If you are really worried about resonance in a large design just ensure there is a bracing every 6-8" and panel resonance will be more than fully attenuated in the typical range of a subwoofer.The real issue with panel resonance is in the 150-1000Hz range.

As far as ply vs MDF. No question ply wins, it is lighter, but actually more stiff (if cabinet grade material is used). This means the ply will actually be less resonant than a similarly braced piece of MDF.

-Andrew
 

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Re: mdf or plywood?

I have no idea what an EBS is.

While Ply is structurally superior, you need bracing to keep the large panels from resonating. Each brace effectively cuts a large resonating panel into smaller panels that wont resonate (hopefully) in a frequency that makes a difference to your sub.
Trust me, I know. ;)

EBS stands for Extended Bass Shelf:
http://www.diysubwoofers.org/prt/ported5.htm

The term is known, understood and recognized by the engineering community (AES, IEEE, etc). The term 'LLT' is little more than a customized EBS and is known only in forums like this one. Mention LLT outside these forums and you will get a bunch of blank stares.. :)
 

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Re: mdf or plywood?

So with everything said above, is plywood ok for an IB manifold? No way I can get an MDF manifold in the attic, no way I can assemble on up there either. I figure I can do a little bracing as well, it would have to be right down the middle, but I guess it's better than nothing.
 

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Re: mdf or plywood?

So with everything said above, is plywood ok for an IB manifold? No way I can get an MDF manifold in the attic, no way I can assemble on up there either. I figure I can do a little bracing as well, it would have to be right down the middle, but I guess it's better than nothing.
Absolutely plywood is ok for that. Which comments thus far have made you think otherwise? :scratch:

I use plywood whenever I can afford it. My current beast of a subwoofer is a real mish-mash of materials - plywood for the outer 'shell', particleboard (yes, not MDF) for the inner front and rear baffles, and hardboard screwed liberally to the particleboard as trim. Internal bracing is a complete frame of 2x2 to hold all the panels together, and front to back bracing using six 2x4s. I had almost no tools at the time of construction, and not much money. I also didn't want a box that weighed 200+ pounds. 130 pounds is enough! Unfortunately now it's more like 147 pounds thanks to the Tempest-X upgrade.
 

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Re: mdf or plywood?

I want to know what difference fellow members find when the subbox is built in mdf of plywood.
Without A doubt if you have the wood working skills 1"-2" thick MDF will give you the best finnish and (sound quality :hide:) in the end product especialy if you want it painted, just look what all the High end home audio sub manufactures like JL Audio's Fathom subs are made out of and most high end Speakers.... But MDF is very easily marked and makes heaps of fine dust when cuting and routing also MDF is very poisonous so it pays to wear A good quality Dust mask and eye protection.....

Ply is more durable and used alot in the Pro audio industry for speakers and subs, mainly because of its lighter weight and durability.....

Cheers.....
 

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Re: mdf or plywood?

Without A doubt if you have the wood working skills 1"-2" thick MDF will give you the best finnish and (sound quality :hide:) in the end product especialy if you want it painted, just look what all the High end home audio sub manufactures like JL Audio's Fathom subs are made out of and most high end Speakers.... But MDF is very easily marked and makes heaps of fine dust when cuting and routing also MDF is very poisonous so it pays to wear A good quality Dust mask and eye protection.....

Ply is more durable and used alot in the Pro audio industry for speakers and subs, mainly because of its lighter weight and durability.....

Cheers.....
This is not really the case. Most mass produced speakers are made from a MDF product because they it is far easier and less expensive to machine than plywood, not because they are superior. The opposite is true, in fact. MDF less stiff than plywood meaning it is likely to be more resonant, but of course MDF is cheaper. Just because the well known brands use the material does not make it good. It just means it is cheap and easy to work with.

Also note, increasing thickness of a material (using 1-2" over 3/4") is an extremely inefficient way to minimize resonances and cabinet flex. Rather, use of a constraint layer and efficient XYZ bracing techniques is a far superior way to mitigate such issues. Now, with the typical passband of subwoofers the differences between ply and MDF are not an issue, but with loudspeakers it is an issue.

Additionally, it requires more than a good dust mask to filter MDF particles due to the use of formaldehyde a chemical rated respirator should be used.
 

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Re: mdf or plywood?

Hi avaserfi,
I guess We agree to disagree on which is the better product to use for building A sub or speakers when given the 2 choices MDF or PLY....

I will say IMO that MDF is A better product to work with and gives very good results if you have the wood working skills, design and construct the box correctly...
The down side of MDF is that of course it is very poisonous :yikes:....

I am pretty sure the B&W 800 series speakers are made in part with PLY.....

Cheers....
 

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Re: mdf or plywood?

Bill said:
I'd never build a reflex box that large, in the same space a folded horn would work far better
Not really. If one's subwoofer goals are a naturally flat and extended frequency response, low distortion, and ample headroom, there is no alignment that can best a LLT on a driver for driver basis.

mrogowski said:
The term is known, understood and recognized by the engineering community (AES, IEEE, etc). The term 'LLT' is little more than a customized EBS and is known only in forums like this one. Mention LLT outside these forums and you will get a bunch of blank stares..
EBS is an extremely generic and vague alignment description that doesn't ensure any level of performance and has very limited characteristics. From diysubwoofers.org:

diysubwoofers.org said:
The volume of the box is larger (sometimes significantly larger) than that of a maximally flat ported system using the same driver.
The tuning frequency of the enclosure is at or close to Fs, the driver's resonance frequency
The power handling of the EBS is lower in the midbass frequencies when compared to the maximally flat systems. However, the power handling at lower frequencies is usually better.
As with the standard ported systems, almost any driver can be used. However, the best results will be obtained with drivers of Qts <0.35.
Based on those "guidelines", an EBS can be a 50 liter enclosure tuned to 35hz using a 1" diameter port :gulp:

LLT is an alignment that meets a certain set of guidelines that ensure a subwoofer that achieves the best balance of linear FR, non linear FR, and headroom for a given, acceptable driver for the dollar. Is LLT a recognized, audio community term? Who cares :daydream:
 

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Re: mdf or plywood?

I just finished building my second IB manifold. My first was IB was built from MDF, this one from ply. They were both very strong. I could stand on either without issue. I can pick up the new manifold which will house 4 18's with one hand, I had to have help picking up the 2 15" manifold. Very important to me as this will be an attic mount. I did give the wood a coat or two of paint to act as a moisture barrier. Next weekend it should go up.
 
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Re: mdf or plywood?

do you mind posting your design box for such project we really appreciate it
 

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Re: mdf or plywood?

Sure. All of the pictures are over in the IB area in the thread IB II, but here are a few. As far as design, there really is not one. It needed to hold 4 18's and fit between 24" on center ceiling joists. I'm not a very good wood worker, but, this box is solid. I've stood on it and it did not even creek.... I'm 6'3 and weigh quite a bit. I sat the twins on top of it, it held up for that too.

Like I said, it's just an ugly box...


Mock up



Glued and Screwed


Holes are cut


Like I said, I can stand on it


The other 2 drivers should be here on Thursday


I wanted them to all be innies,but, it just did not work. I'll have to do all of them as outties now, that's ok.. I think. I hope the rafters don't get in the way once I get it in the attic. If so, I can mount the 2 rafter side drivers from the inside, but, they will lose some of the extra support, No way i can fit back in there to install from the attic side, it'll all be done from the floor except for running wires.

Oh, I painted the inside black as you can see, just so there is no distracting contrast between the drivers and the wood. The drivers are MJ18's, i got a of a deal on them from Otto. I also gave the outside of the box a coat of enamel spray paint I had left over... Not to make it pretty, but, to help as a moisture barrier.

Before the install, I plan to caulk the joints, maybe add a few glue blocks to the inner joints and touch up the spray paint. Still need to cut the hole and get the grill cover figured out, but, I think I'm just going to make a basic frame out of 1x2 and then mount an air return vent to that. The biggest size I can find at Lowes is 20x20 and the hole is going to be an bit larger than that as the box is 21x19
 
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Re: mdf or plywood?

men that's a sturdy box :clap:..ill post mine too once i finish my project.. im using 3/4 plywood..
 
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