We did an experiment building 2 identical pair of cabinets, one out of ply, one of mdf, and conducted a single blind test. No-one in the test expressed an inability to hear the differences. Preferences varied, but the reasons why were very telling.
dave
solid wood is good
i,ve been building furniture for many years any know all about wood movement and how to work around it,i want to build solid wood speakers but dont know the best wood to use im guessing the heavyer&denser the better ,wood will shrink and expand seasonly theres no getting around that fact but only across the grain not the length of the grain that being said ,if you build the top,bottom and sides out of real wood the movement will occur front to back the problem is the front &back panel when you glue it on securely ,depending on the time of year you build them one of 3 things will happen the panel will crack when it trys to shrink to release stress ,the glue joint will fail or the panel will expand and blow the joint apart, i suggest using ply or mdf with a veneer for the front and back panels
i,ve been building furniture for many years any know all about wood movement and how to work around it,i want to build solid wood speakers but dont know the best wood to use im guessing the heavyer&denser the better ,wood will shrink and expand seasonly theres no getting around that fact but only across the grain not the length of the grain that being said ,if you build the top,bottom and sides out of real wood the movement will occur front to back the problem is the front &back panel when you glue it on securely ,depending on the time of year you build them one of 3 things will happen the panel will crack when it trys to shrink to release stress ,the glue joint will fail or the panel will expand and blow the joint apart, i suggest using ply or mdf with a veneer for the front and back panels
As usual in these types of discussions, there seem to be two distinct camps who hold steadfastly to their views, based on whatever experience or data they have chosen to believe. Both are valid.
For low frequnecy enclosures, my choice is to combine both methods by building rigid, double-layered enclosures with one layer of plywood, one of MDF or even particle board. Belt AND suspenders! The layers are securely attached (laminated) because I don't possess the technical ability or patience to incorporate proper CLD procedures. Although CLD can be very effective, if not done properly, it will not function as intended and is certainly not worth the effort.
My most recent build also features a 2" layer of concrete poured in the bottom with a very rough finish. It helps to stabilize a tall enclosure, but it sure adds mass!
One could build an enclosure of a single layer, using alternating panels of both types of material, or attach large panels of the different material internally.
The boxes resonate, I'm sure, but not all panels at the same frequency or the same volume. They might even cancel at some points. They certainly don't ring.
For midrange and tweeter enclosures, I prefer stiff and light plywood with good bracing, small panels, and lots of absorbent stuffing such as cotton batting and wool fiber.
Peace,
Tom E
For low frequnecy enclosures, my choice is to combine both methods by building rigid, double-layered enclosures with one layer of plywood, one of MDF or even particle board. Belt AND suspenders! The layers are securely attached (laminated) because I don't possess the technical ability or patience to incorporate proper CLD procedures. Although CLD can be very effective, if not done properly, it will not function as intended and is certainly not worth the effort.
My most recent build also features a 2" layer of concrete poured in the bottom with a very rough finish. It helps to stabilize a tall enclosure, but it sure adds mass!
One could build an enclosure of a single layer, using alternating panels of both types of material, or attach large panels of the different material internally.
The boxes resonate, I'm sure, but not all panels at the same frequency or the same volume. They might even cancel at some points. They certainly don't ring.
For midrange and tweeter enclosures, I prefer stiff and light plywood with good bracing, small panels, and lots of absorbent stuffing such as cotton batting and wool fiber.
Peace,
Tom E
This one was new to me. How come?
I tried to Google holey braces to no avial. What are they?
I take it that the flange is not physically fastened to the baffle, just tuching the sealant? Otherwise you could really get the box to vibrate.
I'm a very slooooooooooow learner. I've grasped the genral idea of CLD, but how are you supposed to attach the six outer panels to each other? Do one build a like a smaller box that fits within the larger box? I take it the driver goes to the xxx baffle, if so, how do you seal the two boxes off from each other? I am thinking especially of a sandfilled variety now.
Is it OK to use small strips of material for getting consistant distances between walls (they need not be continous)?
I know of some stuff that works between the panels, but there aught to be some range of elasticity values to keep within if one would like to search for additional stuff?
I've heard they can be difficult to glue so that they stick together, but that might have been the oiled version?
It doesn't need to add that much mass. Dickason suggested roofing felt, and you only have to apply it to at least 50% of each panel surface.
Could it be the BBC paper that is referred to? I think it is from the 70's. I think I've seen at least two BBC papers about enclosure material. I had the same problem with the Google translation, but worse, I had to translate one level more. I have more confidence in the BBC paper, method wise. It has quite a different result and ranking.
I've seen someone writing that for a sub enclosure, CLD is not recommended. I might have the source somewhere, but does anybody have any idea what could have been meant?
Step by step : as long as the braces don't interfere with the movement of the cone , like too near or too 'congesting' ; also dowels ....
I was thinking of bars ,not dowels ,opposed to flat surfaces with holes in it ,like we see often on Planet10's prospects ; so I was to say that those planes with holes ( holey ) would distribute far better cinetic energy ( the extra ,bad one !! ) along the structure ...otherwise a simple bar connecting the opposite walls of a cabinet may start itself to add resonances ,in the wrong places ....Ok ,never mind !
I'd need more context to know what i was talking about. It was not the BBC papers. I have had the pleasure of living with some BBC monitors. There approach is quite different than mine.
dave
If one follows the research that shows that a resonace across the narrow dimension dominates, one can formulate this rule: any brace should be such that the ratio of the dimesions of the subpanels should be larger than the ratio of the panel being braced. Further they should have dissimilar ratios. If the subpanel ends up being trapezoidal, even better.
It is easy to see that the typical shelf brace pushes the subpanels closer to square and can, in theory, actually increase objectionable reasonances.
The term holey brace is mine (and the cheerleading), and catching on. It is a full panel brace with 30-40% round holes in it. 1st the holes allow more or less unimpeded LF air flow while allowing a brace that hits 4 sides continuaously. No corners in the cut-outs creates a stronger brace (ref arches) and a more complex resonant structure (leading to wider bandwidth damping. The off-centre brace also sets up a more complex internal standing wave structure. To stand across the box a wave has to pass thru the holes, diffraction thru these dissipates energy. 2 other standing waves can set up between the solid parts of the brace and the walls, but being approx an octave higher are easier to control with damping. That any of these do not have a continuous structure to form against also diminishes them.
I (usually) orient the primary brace to follow the rule above, and such that i can use it to remove parasitic driver energy from the baffle to 3 other panels, distributing it across more panel (sharing the energy acoss more box, reducing it (hopefully) below the threshold required to cause a panel to resonate, and to make more of the panel's damping available). The other panels are also, less detrimental if they do get excited (facing away from the listener).
dave
Ive used a similar brace to P10's, I think i got it from Weems' book, or Kapels'.....such are the limitations of my knowledge other than from this forum.
I built a 16 litre box some years ago, and was cheap and went for 12mm MDF.
Almost needless to say, the MDF was really too thin for a sturdy box of this size, but i was young and inexperienced.....
I tried bracing with dowel, and found that unless the end is ABSOLUTELY square and close fitted, ALmost nothing happens with a single brace.
A shelf brace was used in the end, although AGAIN in my inexperience, I placed it horizontally about 2/3rds along the box under the woofer. In my case i would estimate i drilled holes 30mm diameter and 25mm in diameter and perforated it to as larger an extent as possible. probably maybe 60% or more.
MY brace did not support the rear of the bass driver, which would have been a great improvement. Even so, the effect was very obvious. vibration of the side panels ( um ~16"x11" ), was greatly reduced.
I dont know how P10 or others who have experience with these braces feels about what ill say next but, I actually think you can take the perforation of the brace to more than 50% of the braces area, without detriment to perceived performance, within reason of course.
The next thing im trying on a project is holey bracing, in a pattern something like this:
If my drawing is interpretable! side view of panel, and bracing pattern, roughly a la acoustic guitar soundboard, to allow the thin board to take the tension of the strings...
I built a 16 litre box some years ago, and was cheap and went for 12mm MDF.
Almost needless to say, the MDF was really too thin for a sturdy box of this size, but i was young and inexperienced.....
I tried bracing with dowel, and found that unless the end is ABSOLUTELY square and close fitted, ALmost nothing happens with a single brace.
A shelf brace was used in the end, although AGAIN in my inexperience, I placed it horizontally about 2/3rds along the box under the woofer. In my case i would estimate i drilled holes 30mm diameter and 25mm in diameter and perforated it to as larger an extent as possible. probably maybe 60% or more.
MY brace did not support the rear of the bass driver, which would have been a great improvement. Even so, the effect was very obvious. vibration of the side panels ( um ~16"x11" ), was greatly reduced.
I dont know how P10 or others who have experience with these braces feels about what ill say next but, I actually think you can take the perforation of the brace to more than 50% of the braces area, without detriment to perceived performance, within reason of course.
The next thing im trying on a project is holey bracing, in a pattern something like this:
If my drawing is interpretable!
side view of panel, and bracing pattern, roughly a la acoustic guitar soundboard, to allow the thin board to take the tension of the strings...
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I must have misunderstood you, I thought that you referred to a paper that compared different enclosure building materials.
The next thing im trying on a project is holey bracing, in a pattern something like this:
If my drawing is interpretable!
I don't think that is a good idea. Vibrations from the magnet structure will propagate through your braces to the box walls. I was thinking in the same track a while back. I was to clamp the magnet structures in a "holey brace" paralell with the baffle. That was before I came across alternative ways of attaching a driver to the baffle. Now I will try to isolate the driver by using rubber grommets, as shown by Linkwitz and a paper from a Pioneer guy who did a study on the subject.
I've divided the last quote in two. In 1. I've language or stupidity problems as I cannot really grasp the context of what you wrote. That is, the part that I've put in brackets. The dissimilar ratios, is that due to that bracing should be done with irregular distances?? What is a typical shelf brace? Is it a square with a large square whole cut in it, just leaving like a rim of the original square?
2.
The first time that I can remember seeing a "holey brace" was at the CSS site showing a box example for their original SDX15 subwoofer driver. That box had the magnet structure clamping idea incorporated into a "holey brace" parallell to the baffle.
My plan is to use several "holey braces" both horizontally and vertically, and then attach smaller bits of material where there are no "holey braces" attaching the box walls, and place them perpendicular to the box wall, and so that they connect two "holey braces" and the box wall. I don't want too many "holey braces" in the box, and if I make the bits like 4" deep into the box, my thought is that they will contribute some additional stiffness without adding that much material. I hope I've not been to unclear?
Sharing energy from the driver with multiple panels is better than having the baffle -- weakest & mot audiable panel -- bear all the energy itself.
A brace parallel to the baffle anywhere in the vicinity of the driver is not a good thing.
I also found the grommet isolation to be counterproductive.
Yes, Yes.
That was my drawing. The clamping of the magnet idea was Dan Wiggin's, i had in the past provided only a rest
As long as opposite box walls are tied together you should be OK... doing a full width brace is probably easier, and you make sure it is effective.
dave
1. I was thinking of having such a brace as the origin of my brace matrix, if that's the word? Is it due to risk for restricted air flow behind the drivers? How would you define "in the vicinity"? For me it is too vague an expression as a guideline. In my case, I'm gonna use dual 10" in one box.
What about a horizontal brace, attaching all four walls, centered between the woofers?
2. In what way? Did it sound worse or did you measure? Both Linkwitz and the Pioneer employee found improvements in panel vibration reduction.
3. Why I considered this approach was to try to reduce the amount of bracing material and still make the box stiffer as added weight counters the effect of stiffening. Unfortunately I'm not an engineer, so I have no idea how it would come out, it sounded good thogh, to me.
Can you give any general guidelines about how thin you can have the box walls for different driver sizes as a starting point? I'll be using BB plywood.
I was thinking more in the way of a "holey brace", but that might be as bad an idea as a paralell holey brace too close to the baffle (whatever distance that might be)?
Having browsed this thread of all threads I would now like to for the first time try plywood for a sub of 60 Liters. I'm thinking of 24 mm (12mm+12mm) and with bracings.
Planet 10 wrote:
"I'd brace them for sure. What you need to ensure with a sub is that it doesn't balloon.
With your dimensions i'd probably have at least 4 braces --all running in the long direction and perpendicular to the long panels."
Could you explain "running in the long direction".? It seems you mean put all in paralell only, not obstructing the flow from the cone. One would think bracing in 3 dimensions with a lot of holes would be so much stiffer (like B&W)?
Planet 10 wrote:
"I'd brace them for sure. What you need to ensure with a sub is that it doesn't balloon.
With your dimensions i'd probably have at least 4 braces --all running in the long direction and perpendicular to the long panels."
Could you explain "running in the long direction".? It seems you mean put all in paralell only, not obstructing the flow from the cone. One would think bracing in 3 dimensions with a lot of holes would be so much stiffer (like B&W)?
Shinnoki
Hi,
Has anybody used Shinnoki? It's high quality pre-veneered MDF.
Veneer panels for building and interior design - wood veneer boards - SHINNOKI Real Wood Designs
A local wood shop has them (not seen yet) but they look gorgeous. Mitre Joints would be needed though.
Cheers
Hi,
Has anybody used Shinnoki? It's high quality pre-veneered MDF.
Veneer panels for building and interior design - wood veneer boards - SHINNOKI Real Wood Designs
A local wood shop has them (not seen yet) but they look gorgeous. Mitre Joints would be needed though.
Cheers
One would think, but it is primarily the shortest dimension that determines the panel resonance. Adding more in the other direction, pushes subpanels towards being square and may actually be more likely to resonate. In a subwoofer you usually don't have to worry as long as panel resonant modes are higher than your passband.
In a TL design the braces need to run the same direction as the 1/2 wave action.
dave
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