Is it possible that many people have MDF and High Density Particle board mixed up?
MDF is made of fibers, much like cardboard, but highly compressed.
HDP is made of sawdust, and I suspect, more of the harmful glue that causes it to be resonant. (It certainly dulls cutting edges much more quickly) It's a good substrate for laminates like formica because it is hard enough not to compress from a sharp blow.
MDF also isn't particularly strong either, (as has been alluded to) not that cabinets are under high stress. It is a good substrate for veneer, mostly because it accepts glues well, and is flat and smooth.
About the resonance of boxes:
It would also be interesting to have some quantification of the "knock" test. I can see how some coloration using the box _might_ be useful, but absent "a good feel", shouldn't we try to err on the side of non-resonance?
Also, I wouldn't be so quick to condemn all OSB's per se, engineered lumber is the future of sheet goods. There are many new materials being manufactured that have properties far superior to plywoods in many ways. If we knew exactly what we wanted for a partcular need, if it isn't being made, it could be.
MDF is made of fibers, much like cardboard, but highly compressed.
HDP is made of sawdust, and I suspect, more of the harmful glue that causes it to be resonant. (It certainly dulls cutting edges much more quickly) It's a good substrate for laminates like formica because it is hard enough not to compress from a sharp blow.
MDF also isn't particularly strong either, (as has been alluded to) not that cabinets are under high stress. It is a good substrate for veneer, mostly because it accepts glues well, and is flat and smooth.
About the resonance of boxes:
It would also be interesting to have some quantification of the "knock" test. I can see how some coloration using the box _might_ be useful, but absent "a good feel", shouldn't we try to err on the side of non-resonance?
Also, I wouldn't be so quick to condemn all OSB's per se, engineered lumber is the future of sheet goods. There are many new materials being manufactured that have properties far superior to plywoods in many ways. If we knew exactly what we wanted for a partcular need, if it isn't being made, it could be.
mrfeedback said:
That's the problem with "live" material, whether is it wood grains, spun aluminum or molded polymer. You're talking about the "trick" of a properly timed release of stored kinetic energy. With MDF, the "deadness" is the advantage, ensuring that the driver(s) and structural rigidity of the enclosure do the work. Tuning the drivers and speaker placement is hard enough for us mortals, but now you both want to add the phase response(s) of an entire cabinet! Maybe you have the computing power to run the FEA for it, but me I'll stick with "dead accurate."
🙂ensen.
Adrian-
Hold on. You preference for using fiberboards is well noted.
Your arguments against using hardwoods are a little lacking however. First, you say it it isn't as strong a MDF, and it'll crack under stress. Well that just isn't true. You wouldn't build a staircase out of it would you? How about he post under your floor?
Also, you say it has resonance problems that need to be "fixed", so what wrong with that? Bracing MDF is fixing a problem, certainly _that's_ acceptable, yes?
And you say it's expensive. I contend it doesn't matter that much, especially considering the cost of veneer relative to the beauty of the project.
I'm very interested in this discussion because I'm a woodworker learning to build speakers. I have a mountain of Ply and MDF speakers in my shop that sound great, but few I would want sitting in someone else's living room. Certainly not in a house I've built, along with the staircase, kitchen cabinets, and even the entertainment center.
I hope you see what I'm getting at; the SAF is the difference between these speakers remaining another experiment for my own hobby, or becoming a replacement for a B@$* system and letting others enjoy the sounds as we who have learned something else, hear them.
For some of us, painted finish and no grill cloth is fine. And veneering can give that look that's just as good as some brand names.
But why should any of us who are willing to work for it, be willing to settle for that?
Hold on. You preference for using fiberboards is well noted.
Your arguments against using hardwoods are a little lacking however. First, you say it it isn't as strong a MDF, and it'll crack under stress. Well that just isn't true. You wouldn't build a staircase out of it would you? How about he post under your floor?
Also, you say it has resonance problems that need to be "fixed", so what wrong with that? Bracing MDF is fixing a problem, certainly _that's_ acceptable, yes?
And you say it's expensive. I contend it doesn't matter that much, especially considering the cost of veneer relative to the beauty of the project.
I'm very interested in this discussion because I'm a woodworker learning to build speakers. I have a mountain of Ply and MDF speakers in my shop that sound great, but few I would want sitting in someone else's living room. Certainly not in a house I've built, along with the staircase, kitchen cabinets, and even the entertainment center.
I hope you see what I'm getting at; the SAF is the difference between these speakers remaining another experiment for my own hobby, or becoming a replacement for a B@$* system and letting others enjoy the sounds as we who have learned something else, hear them.
For some of us, painted finish and no grill cloth is fine. And veneering can give that look that's just as good as some brand names.
But why should any of us who are willing to work for it, be willing to settle for that?
x. onasis said:
In Aus, 'chip board' is light/natural coloured saw dust bonded with some kind of glue, and 'MDF' is a medium brown material that shapes to precision and splits into layers.
Eric.
macky888 said:
Ditto.
With all due respect to the posters in question, it is inconceivable that anyone would want an enclosure that adds it's own characteristic to the music. I am particularly surprised at the stance that Nelson Pass has taken on the issue. This viewpoint would be intolerable if the discussion revolved around turntables, CD player or pre-amps. I would have included amps as well but there seems to be a faction that prefers some added 2nd harmonic distortion in power amps.
If one builds an enclosure that adds resonances, even if calculated and controlled, then one is stuck with it. There is no opportunity to "dial out" or alter these resonances if it seems appropriate to do so for a particular piece of music. Better, I believe, is to have a black box between the pre-amp and amp which can control the frequency and intensity of injected resonances. Each frequency control could have associated Q and timing knobs so as to allow the fine tuning of ringing. Sort of a glorified EQ, reverb and special effects generator.
To promote the concept of intentionally resonant enclosures is to do a grave disservice to the DIY community. It will waste time, money and result in much unhappiness.
Of course if it turn out that this thread is about speaker cabinets for guitars then I withdraw my comments.
Though I basically belong to the "dead cabinet" group I can understand the other side as well.
25 years ago when I was an apprentice I had to repair a lot of old tube radios. Those were of course not very accurate but had a sound that was easy on the ear. This was also partially caused by their wooden cases and FR drivers.
Regards
Charles
25 years ago when I was an apprentice I had to repair a lot of old tube radios. Those were of course not very accurate but had a sound that was easy on the ear. This was also partially caused by their wooden cases and FR drivers.
Regards
Charles
Looking at it from another angle.
A guitar is a resonant musical insturment, so if you built a guitar out of MDF or partical board it would sound dead.
Maybe the driver cant have the total range of resonances ,and if it does it may not sound natural,of a guitar.So a slightly resonant cab may (<---keyword) make up the difference between what an electro mechanical transducer can accomplish and what it cant.
I have built cabs (a lot of them) with MDF in the past and yes they are dead, but so is the sound.Anything will resonante given the proper frequency imput, but the degree and the length of time(wavetrain length) it resonants is dependant on the subject material.
I tend to look at cabs ,although all i make is horns now,as something to assist the driver in reproducing what actually took place at the time of the recording even given the fact that someone playing a guitar,for example,that the signal is filtered ,tuned, altered and generally changed from what what was occuring in the studio room.
ron
A guitar is a resonant musical insturment, so if you built a guitar out of MDF or partical board it would sound dead.
Maybe the driver cant have the total range of resonances ,and if it does it may not sound natural,of a guitar.So a slightly resonant cab may (<---keyword) make up the difference between what an electro mechanical transducer can accomplish and what it cant.
I have built cabs (a lot of them) with MDF in the past and yes they are dead, but so is the sound.Anything will resonante given the proper frequency imput, but the degree and the length of time(wavetrain length) it resonants is dependant on the subject material.
I tend to look at cabs ,although all i make is horns now,as something to assist the driver in reproducing what actually took place at the time of the recording even given the fact that someone playing a guitar,for example,that the signal is filtered ,tuned, altered and generally changed from what what was occuring in the studio room.
ron
I agree, no resonance. I have a neighbor who owns a countertop fabrication business. He has given me some Corian (solid surface counter top material) scraps and I have fabricated a simple single driver horn enclosure out of these scraps with very good results. The nice thing about this material is that it is very dense, a very, very low resonant frequency, no fasteners, epoxy does the trick and can be worked with normal woodworking tools. The down side is that it is very expensive. I am not suggesting that everyone contemplating a speaker project run out and buy Corian or a Corian clone, but if you have access to scrap, it does bear consideration.
A common misconception is that stiffer or denser materials would resonate less. If this were true, bells would be made out of pudding or something similar. 😉
It is the internal damping of a material that makes it non-resonant.
There was an AES article, written by engineering staff of NHT, who claimed that it is audibly better (and also cheaper) to spread resonances over a broad frequency range than trying to fully avoid them.
Regarding transients and resonances: If a resonance has a high Q it is less likely to be excited by short transients.
Using sustained signals of a frequency equalling the resonant frequency things would of course look different. But natural sounds with a long sustain usually don't decay by themselves very quickly so the influence of a cabinet resonance on transients may be much smaller than one is led to assume.
Just keep in mind: The ideal speaker hasn't been built yet and will never be built. So YOU have to pick your favourite compromise.
Regards
Charles
It is the internal damping of a material that makes it non-resonant.
There was an AES article, written by engineering staff of NHT, who claimed that it is audibly better (and also cheaper) to spread resonances over a broad frequency range than trying to fully avoid them.
Regarding transients and resonances: If a resonance has a high Q it is less likely to be excited by short transients.
Using sustained signals of a frequency equalling the resonant frequency things would of course look different. But natural sounds with a long sustain usually don't decay by themselves very quickly so the influence of a cabinet resonance on transients may be much smaller than one is led to assume.
Just keep in mind: The ideal speaker hasn't been built yet and will never be built. So YOU have to pick your favourite compromise.
Regards
Charles
The BBC designs traditionally used a thin plywood wall, heavily damped with bitumous pads. The argument was that they couldn't get rid of the resonances in the panels altogether so they would try and shift it to a frequency where it did less damage.
An alternative approach I've heard work well uses relatively thin chipboard panels with fibreboard damping. This gives quite a light enclosure with panels which, when they resonate, do so over a broader band but stop and start very quickly. You could probably do this with real hardwood panels.
The most inert speakers I've heard used plaster as a lining material to produce enclosure walls which produced very little output.
It's not the material, it's how you use it and how much you want to experiment.
btw, a good check for resonance in panels is the sand test - turn the enclosure on it's side and sprinkle some sand on the cabinet (keep well away from drivers), then play music and see if the sand starts to dance. Very entertaining with some commercial speakers ...
Colin
An alternative approach I've heard work well uses relatively thin chipboard panels with fibreboard damping. This gives quite a light enclosure with panels which, when they resonate, do so over a broader band but stop and start very quickly. You could probably do this with real hardwood panels.
The most inert speakers I've heard used plaster as a lining material to produce enclosure walls which produced very little output.
It's not the material, it's how you use it and how much you want to experiment.
btw, a good check for resonance in panels is the sand test - turn the enclosure on it's side and sprinkle some sand on the cabinet (keep well away from drivers), then play music and see if the sand starts to dance. Very entertaining with some commercial speakers ...
Colin
The resulting sound is the only consideration.
Inert materials are much easier to design with, no doubt,
and I'm not going to argue that good sound cannot be had
that way.
Live materials are much more difficult to design with, but when
it works (rarely) the results are spectacular.
The Rushmores are on the cover of Stereo Sound this month,
and have generated great excitement based on the sound.
Their drivers are very sensitive and have a live character, and
the sides of the enclosure, a curved surface made of the same
kind of molded veneer layers you would find in a piano, are
quite live.
You don't like these ideas? I've got others.
Inert materials are much easier to design with, no doubt,
and I'm not going to argue that good sound cannot be had
that way.
Live materials are much more difficult to design with, but when
it works (rarely) the results are spectacular.
The Rushmores are on the cover of Stereo Sound this month,
and have generated great excitement based on the sound.
Their drivers are very sensitive and have a live character, and
the sides of the enclosure, a curved surface made of the same
kind of molded veneer layers you would find in a piano, are
quite live.
You don't like these ideas? I've got others.
I've built a small minimonitor this year, using 3/4" maple boards. This is the best sounding speaker I had so far.
Wood Can Be Good...........
The light boxes that I have heard that sound good had a heavier front panel.
With real wood, the nature of the box sound can be chosen.
With MDF or chip board, the sound is, well, like MDF or chipboard.
The fingernail tap test reveals different types of wood to sound different, and different pieces of the same type to sound different.
Stradivarius worked this out a very long time ago.
Peter, did you see the bee-hive box suggestion ?.
Eric.
The light boxes that I have heard that sound good had a heavier front panel.
With real wood, the nature of the box sound can be chosen.
With MDF or chip board, the sound is, well, like MDF or chipboard.
The fingernail tap test reveals different types of wood to sound different, and different pieces of the same type to sound different.
Stradivarius worked this out a very long time ago.
Peter, did you see the bee-hive box suggestion ?.
Eric.
If you go back and look at what I wrote one page one you will see that the idea is to create a box that is harder for the sound to excite by multiple nodes at higher freqs. The idea that a box should be allowed to resonate as part of the speakers 'sound' is just wrong! It is a distortion of the recorded signal. In a guitar cabinet it is a purposeful part of the sound, not in a hifi speaker. I mentioned corian then too as a great but pricy material. The main thing is real wood has properties that make it less suitable for a stable, non-resonant, practical speaker eclosure. 25 years of working in the field has led me to this conclusion as I've tried it all and come back to variations on the MDF theme every time.
So, now I have to ask...
Are the hardwoods being used, single boards per side or are they laminated together like a chopping block? I'm guessing that laminated boards are beginning to act like any other composite structure and thus are providing some damping within the panel.
🙂ensen.
Are the hardwoods being used, single boards per side or are they laminated together like a chopping block? I'm guessing that laminated boards are beginning to act like any other composite structure and thus are providing some damping within the panel.
🙂ensen.
In my case I used 1/4" MDF panel as a base and 6 x 1" maple boards are glued to it. This makes the side walls more dimentionaly stable (the boards are on the outside). As to the top and bottom panels, I used 5/8 MDF on the outside and 3/4" maple boards are on the inside, glued together. As top and bottom were laminated after, this was a better way to go. When laminating on maple, after some time the boards tend to warp and surface is not flat anymore.
Nice! Construction techniques befitting someone with "Boeing" in their avatar.
Interesting. Only the 4 side panels are MDF on the inside. I'm curious... why did you put the MDF on the outside for the top and bottom panels?
🙂ensen.
Interesting. Only the 4 side panels are MDF on the inside. I'm curious... why did you put the MDF on the outside for the top and bottom panels?
🙂ensen.
I put the MDF on the outside of top, bottom and rear panels as I wanted them laminated (the whole maple box looks boring IMO). Maple doesn't provide good base for lamination. On the contrary the side panels are supposed to be maple on the outside, that's why the MDF is on the inside😉 It also helped me to assemble the whole thing easier, as first I glued top, bottom, front, back and all the bracing inside, then attached 1/4 MDF panels to the sides, and then after that attached the side maple boards using carpenters glue. A structure built in this way is more stiff, I guess.
http://www.diyaudio.com/forums/showthread.php?s=&threadid=16237
http://www.diyaudio.com/forums/showthread.php?s=&threadid=16237
Isn't just about any enclosure intentionally resonant? Vented, BP, T-L, etc. So, howz about we just try out certain materials ourselves and post up the results (that is what DIY is about ins't it?). For moi, I prefer the addage, "If ain't baroque don't fix it." no wait, "If ain't broke don't fix it." MDF works, let's leave it at that.
Variables in selecting a wood for an Enclosure
When: using MDF purchased only sheets made without formaldehyde glues.
As for using hardwoods, different hardwoods have very different densities. With high-density wood the resonance factor should increase, however the grain structure will play some factor. In building a sold wood enclosure, one should use a wood that has a very small tangential expansion property. Among these types or Mahogany, Teak, Wenge, Bubinga and Cedar. Maple, Oak, Ash and Walnut have a high Tangential expansion. In addition falt sawn wood will bow over time where quarter sawn will be less likely to.
Wood that or of very high density include:
Bubinga, Ebony, Jarrah, Lignum Vitae, Mesquite, Rose Wood, Purple Hart, Satinwood, Wenge, Tulipwood, Zircote, Coco Bola, Zebrawood and Padauk.
Woods that or medium to medium-high density are:
White and Red Oak, Hickory, Pecan, Maple, Cherry, Iroko, Teak, Birch.
In addition, some woods very in density from boards to boards these are: Mahogany, Luan,
In addition, to note the type of the cut may make a difference in the resonance of the cabinet and.
If building a laminated enclosure one should use a base of MDF or Baltic Birch Plywood.
Then have a high-density wood re-sawed and glued to the base. For curved cabinets, one could use different densities of wood before then glue them in a form much like B&W does.
As for mounting mid and tweeters, why not use an aluminum plate that is connected to either the MDF or wood enclosure.
When: using MDF purchased only sheets made without formaldehyde glues.
As for using hardwoods, different hardwoods have very different densities. With high-density wood the resonance factor should increase, however the grain structure will play some factor. In building a sold wood enclosure, one should use a wood that has a very small tangential expansion property. Among these types or Mahogany, Teak, Wenge, Bubinga and Cedar. Maple, Oak, Ash and Walnut have a high Tangential expansion. In addition falt sawn wood will bow over time where quarter sawn will be less likely to.
Wood that or of very high density include:
Bubinga, Ebony, Jarrah, Lignum Vitae, Mesquite, Rose Wood, Purple Hart, Satinwood, Wenge, Tulipwood, Zircote, Coco Bola, Zebrawood and Padauk.
Woods that or medium to medium-high density are:
White and Red Oak, Hickory, Pecan, Maple, Cherry, Iroko, Teak, Birch.
In addition, some woods very in density from boards to boards these are: Mahogany, Luan,
In addition, to note the type of the cut may make a difference in the resonance of the cabinet and.
If building a laminated enclosure one should use a base of MDF or Baltic Birch Plywood.
Then have a high-density wood re-sawed and glued to the base. For curved cabinets, one could use different densities of wood before then glue them in a form much like B&W does.
As for mounting mid and tweeters, why not use an aluminum plate that is connected to either the MDF or wood enclosure.
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