I want to know what difference fellow members find when the subbox is built in mdf of plywood.
Would you guys still use 1/2" material if you were building an LLT? Say something 4' X 4' X 2' for example?Like Bill said, MDF for test boxen because it is cheap, 7 ply birch (or better yet, fir) for finished goods.
Best,
Mark
By LLT you mean EBS right?Would you guys still use 1/2" material if you were building an LLT? Say something 4' X 4' X 2' for example?
Absolutely plywood is ok for that. Which comments thus far have made you think otherwise? :scratch: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.
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.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.....
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.Bill said:I'd never build a reflex box that large, in the same space a folded horn would work far better
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: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..
Based on those "guidelines", an EBS can be a 50 liter enclosure tuned to 35hz using a 1" diameter port :gulp: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.
I certainly wouldn't say that manufacturers use MDF only because it's cheaper. That's only one factor - though one of vastly more importance to a high production manufacturer than a home builder. I would say of equal importance are it's ease and stability of machining, and uniformity for applying a veneer....
People seem to think that because plywood costs more, it is a better building material for speakers and I don't think that is true. To suggest that high end speaker companies use it because it is cheaper is just crazy. 1" MDF is about $50 a sheet and 1" ply is about $100 a sheet, that would easily make a set of speakers. I can't confirm this, but every high end speaker I have seen is MDF.
Now, using if for the reasons of easier to work with, that is a very good reason.
...
By cabinet grade do you mean A-1? This is not what you find at your local home depot and basically it is the same wood, just better veneer on it. If you are going for superior, why not recommend 1" ply?You are right MDF is far more dense, but cabinet grade ply being more stiff allows for a less resonant cabinet. That is why ply is superior, of course, if MDF is properly used a completely inert cabinet can result.
Duh. OK, makes sense. I didn't quite think it through the other night. I suspect you can increase resistance to vibration by coupling two materials of different resonant properties and stiffness together.Dampening factor is basically the resistance to the mechanical motion from other forces.
That leads to questions on the effective use of the material you have chosen. I know its ouside of the thread topic, but these two things are very closely related and should both be considered.A cross brace running the full length of 2 opposing surfaces serves two purposes. For one, it cuts the cross section in half, and thus it's fundamental mode of resonance is doubled. For another, it couples two opposing surfaces which are each trying to move in opposite directions, thus cancelling any vibration less the elasticity in the brace (for all intensive purposes this can be assumed to be zero).
I have often wondered if, when given the choice of 1x1/2" brace vs 2x1/4 braces, if we would not be better served by multiple thinner braces.
That leads to another question. If you add mass via MDF to reduce a modal resonance by half, and then add a brace cutting the sheet in half thus doubling the modal resonance, are you not back to where you started (but a lot heavier)?
If I understand damping properly, it is the process of converting energy stored as momentum to energy stored as heat through friction.The more I've been thinking about this the more I think that a single point brace could be nearly as effective as one running the full length
The brace serves as a point on the surface which is constrained and cannot move. The material could still flex between the brace and the next point of constraint.In order for the single point brace to be effective, enough energy being applied to the mass, the side of the box, has to be transfered to the single point brace rather than vibrating the mass (which transfers energy to the surrounding air as sound waves).
That is exactly why I don't think it will be as effective as you think. Unfortunately the math/physics is beyond me.The material could still flex between the brace and the next point of constraint.