Been thinking about what is actually the best material for a speaker enclosure.
I would think the most important attributes would be stiffness and damping.
I have mostly worked with MDF, which is easy to work wit and gives good results. But what if you where to go the full mile?
Wilson uses X-material and M-material .... I would guess that it's some kind of Corian (also used for kitchen tables).
Some is talking about energy storage ..... any thoughts??
What about pure mass .... I would think it is desirable to have as much mass as possible, but I wuld also think what is even more desirable is high density (and therefore high mass)
Thinking about different materials:
Plywood
- Would think MDF is actuallt a lot better
Hard wood (e.g. Mesquite)
- Workable but quite hard
- probably good damping, and relative high resonance
Concrete
- High resonance, very stiff, probably not the best damping
Metal (Alu)
- Stiff, hight resonance, but not the best damping
Stone (Marble, Granite ...)
- Almost imposible to work
- super stiff, high density, high resonance .... would be great looking
Ceramics
- burned clay would be easy to work, if you had acces to an oven
- Very stiff, high density, high resonance, ....
Glass
Plexiglass
Acrylic
Fiberglass (epoxy based)
Do we have to use the same material for all enclosure parts.
Could we consentrate on the enclosure for mid and high??
What about sandwitch materials??
Any thoughts??
And even better experianece??
Best regards Baldin
http://www.thespeakerstore.com/glossary/enclosures.htm
http://diyaudioprojects.com/Speakers/Seas-Granite-Speakers/
http://www.soundstagelive.com/factorytours/wilson/
I would think the most important attributes would be stiffness and damping.
I have mostly worked with MDF, which is easy to work wit and gives good results. But what if you where to go the full mile?
Wilson uses X-material and M-material .... I would guess that it's some kind of Corian (also used for kitchen tables).
Some is talking about energy storage ..... any thoughts??
What about pure mass .... I would think it is desirable to have as much mass as possible, but I wuld also think what is even more desirable is high density (and therefore high mass)
Thinking about different materials:
Plywood
- Would think MDF is actuallt a lot better
Hard wood (e.g. Mesquite)
- Workable but quite hard
- probably good damping, and relative high resonance
Concrete
- High resonance, very stiff, probably not the best damping
Metal (Alu)
- Stiff, hight resonance, but not the best damping
Stone (Marble, Granite ...)
- Almost imposible to work
- super stiff, high density, high resonance .... would be great looking
Ceramics
- burned clay would be easy to work, if you had acces to an oven
- Very stiff, high density, high resonance, ....
Glass
Plexiglass
Acrylic
Fiberglass (epoxy based)
Do we have to use the same material for all enclosure parts.
Could we consentrate on the enclosure for mid and high??
What about sandwitch materials??
Any thoughts??
And even better experianece??
Best regards Baldin
http://www.thespeakerstore.com/glossary/enclosures.htm
http://diyaudioprojects.com/Speakers/Seas-Granite-Speakers/
http://www.soundstagelive.com/factorytours/wilson/
Opinion: Since different designs have different approaches to the goal of moving air: The material should fit the design.
If goal is absorption then I would utilize the concept behind OM ( Opposite Moduli materials ) and sandwich layers.
Also there are the considerations: of what materials are readily available/cost/workability/use, etc. )
There seems to be some consensus that high quality baltic birch plywood is the best material for building speakers, can't remember where i read it, might be this forum.
I thought this TNT Audio article was quite interesting, in that the midrange sounded best with medium thickness plywood. I would have though the plywood would add colouration to vocals and midrange, due to resonating from insufficient stiffness.
Interesting that MDF 'kills' the life of the music. Maybe the author had a personal preference for the 'sound' of plywood.
http://www.tnt-audio.com/clinica/speaker_design_pt1_energy_e.html
http://www.tnt-audio.com/clinica/cabinet_walls_e.html
I thought this TNT Audio article was quite interesting, in that the midrange sounded best with medium thickness plywood. I would have though the plywood would add colouration to vocals and midrange, due to resonating from insufficient stiffness.
Interesting that MDF 'kills' the life of the music. Maybe the author had a personal preference for the 'sound' of plywood.
http://www.tnt-audio.com/clinica/speaker_design_pt1_energy_e.html
http://www.tnt-audio.com/clinica/cabinet_walls_e.html
rhapsodee said:
Let's refine that definition... plywood with lots of plys and no voids (or well filled voids, is the best easily available material for building cabinets using standard wood-working tools.
It is also durable & long-lived (this last giving it a big edge over solid wood, where you have to have skill & take care to not have the cabinets explode or crack with changes in humidity)
It also fits well with a certain philosophy of cabinet design.
This may be the thread rhapsodee regers to...
http://www.diyaudio.com/forums/showthread.php?s=&threadid=98834
I was a major participant in that thread (outlining and defending the specific building philosopy i follow) and butted heads with John alot... i got much satisfaction, when later on in another thread, it was like a ligt went on in John's head, he got it, and declared that it was a brillant way to approach the job.
More exotic materials have their benefits and if i felt it were practical, there are ways to take my technique even further.
dave
Very good response
.... seems this has been discussed before
Birch Ply seems a good choice.
Planet10 do you also use internal bracing for every 7,5 cm or less as Mark Wheeler? (this will push the resonance to over 2,2 kHz)
Do you use thin walls, e.g. 12 mm, or thicker e.g. 25 mm and up?
Of course if you have braces every 5 - 7 cm, 12 mm will probably be enough, but I would tend to go for a thicker front baffle.
Do you also use bitumen to dampen the walls (convert energy to heat)?
I'm still thinking about fiberglass. It prabably have higher inner damping, but I wuold guess it has some of the same benefits as plywood. For a mid high cabinet it would give som very nice sculpturing possibilities (like you se in car subs), making bending walls, reduceing difraction etc. a chields play
The mounting rings could still be made of ply.
http://www.youtube.com/watch?v=I9Snm3SRzeA
(Don't mind the music)
I would strengthen it with a lot more real fiberglass in stead og the filler.
http://www.geocities.com/fiberglassenclosure/Basic_Fiberglass.html
Baldin
.... seems this has been discussed before
Birch Ply seems a good choice.
Planet10 do you also use internal bracing for every 7,5 cm or less as Mark Wheeler? (this will push the resonance to over 2,2 kHz)
Do you use thin walls, e.g. 12 mm, or thicker e.g. 25 mm and up?
Of course if you have braces every 5 - 7 cm, 12 mm will probably be enough, but I would tend to go for a thicker front baffle.
Do you also use bitumen to dampen the walls (convert energy to heat)?
I'm still thinking about fiberglass. It prabably have higher inner damping, but I wuold guess it has some of the same benefits as plywood. For a mid high cabinet it would give som very nice sculpturing possibilities (like you se in car subs), making bending walls, reduceing difraction etc. a chields play
The mounting rings could still be made of ply.
http://www.youtube.com/watch?v=I9Snm3SRzeA
(Don't mind the music)
I would strengthen it with a lot more real fiberglass in stead og the filler.
http://www.geocities.com/fiberglassenclosure/Basic_Fiberglass.html
Baldin
Baldin said:
Not quite that much... the resonance not only depends on distance, but stiffness & mass as well... but we have other tricks
We use 12 to 18mm BB and sometimes will double a panel (or as in many of the Fonkens, use an onken-style port which inherently doubles walls.
No. It takes the panel the wrong direction. Plywood by its very nature has a high damping.
If you laminate the plywood both sides with fiberglass that is definitely taking things in the right direction.
At some point in time i am also going to pour something like polyurethane/epoxt resin.or somesuch into the box and slosh it around to create an even stiffer 2st veneer layer as a budget variation on the fiberglass.
dave
You forgot one:
Oiled softwood (pine, spruce, hemlock, fir):
- Takes on some characteristics of hardwood
- Less resonance than hardwood
- Light weight
- Least wear on tools
- Good damping
- Used throughout the cab and not just the baffle, can become part of the LF driver system and increase LF output over hardwood/MDF (spruce is often used by luthiers for this)
Cons:
- Takes more router skills than hardwood
- Requires more bracing for a sonic-neutral cab
Oiled softwood (pine, spruce, hemlock, fir):
- Takes on some characteristics of hardwood
- Less resonance than hardwood
- Light weight
- Least wear on tools
- Good damping
- Used throughout the cab and not just the baffle, can become part of the LF driver system and increase LF output over hardwood/MDF (spruce is often used by luthiers for this)
Cons:
- Takes more router skills than hardwood
- Requires more bracing for a sonic-neutral cab
Like mentioned: If a cab is going to be move and banged around, I would use the best ply I could find.
Unfortunately in some areas, the better grade BB is not easy to obtain ( and it's never cheap ). So I have to cherry pick from what is available locally or obtain the best stuff from the nearest source ( 200 miles ).
MDF being cheap and fairly easy to obtain is used a lot, but it has workability issues, must be sealed and finished. For PA use it's too heavy and not very durable.
I am aware of a couple of different approaches:
As much mass as possible ( several layers of MDF )
Use of layers of acoustically dissimilar mediums.
and constrained layers.
I have seen a lot of materials used and containers recycled or unusual items converted into enclosures.
The results seemed to be contingent on the implementation more than the material: A unbraced box of thin wood with no dampening, makes a good drum.
I have small speakers made with a metal exterior, KEF 207/2 uses aluminum in the HF spheroid. These are not simple metal cabs but have internal dampening and bracing.
I have heard a oil drum that someone stuck a speaker in: It had no bracing or dampening and it sounded dreadful ( after all they have steel drum bands ).
Unfortunately in some areas, the better grade BB is not easy to obtain ( and it's never cheap ). So I have to cherry pick from what is available locally or obtain the best stuff from the nearest source ( 200 miles ).
MDF being cheap and fairly easy to obtain is used a lot, but it has workability issues, must be sealed and finished. For PA use it's too heavy and not very durable.
I have used it, but as the exterior layer.
I am aware of a couple of different approaches:
As much mass as possible ( several layers of MDF )
Use of layers of acoustically dissimilar mediums.
and constrained layers.
I have seen a lot of materials used and containers recycled or unusual items converted into enclosures.
The results seemed to be contingent on the implementation more than the material: A unbraced box of thin wood with no dampening, makes a good drum.
I have small speakers made with a metal exterior, KEF 207/2 uses aluminum in the HF spheroid. These are not simple metal cabs but have internal dampening and bracing.
I have heard a oil drum that someone stuck a speaker in: It had no bracing or dampening and it sounded dreadful ( after all they have steel drum bands ).
planet10 said:
Absolutely the most sensible way of building, no matter what the material is. Dave showed me the light.
HK26147 said:
Harbeth builds speakers this way. I haven't heard any, but I don't think they sound "dreadful".
Like you say, it's all in the implementation. I think (now) that there is altogether too much done to silence or deaden the box.
I haven't heard them either, I think there exists a Stereophile review,
Of course in this context, the words thin and wood are vague, I have heard boxes made with 1/2 ply and 3/4 play that "ring" initially,
Once it was cross braced to prevent flex and appropriate sound deadening was applied, it's dramatic difference.
And of course molded and formed plastics are used extensively for HF horns
I think the primary sonic problems with MDF are its high resin (glue) content (from which most of its 'strength', such as it is, is derived) that contributes materially to a 'plasticky' acoustic signature, and the fact that it is almost 'too' uniform in a sense, so its resonances tend to be higher Q (Less distributed in frequency) and thus more audible.
BB plywood is good. Void free multi layer is much better than the cheap stuff, of course, but I've heard some of that (not BB) which was still significantly inferior to BB (tore it out of the back wall of a pair of cabinets that were otherwise BB because I could hear its distinct sonic contribution in fact), so the inherent strength and damping of the wood used is important, too, IMO.
For a step up in quality, I laminate 2 3/8" or 1/2" sheets of BB with some elastomeric adhesive such as a high solids contact cement.
I like to use plenty of (circumferential, where possible) edge bracing with plywood, or, better yet, 3" x 3/4" thick oak, with the option of sheathing the bracing material in aluminum or steel plate (all well damped, of course), so there is no unbraced span of more than about 15".
I've also used lead plate screwed and glued (with an elastomer) to solid hardwood cabinet panels, and that works, too.
BB plywood is good. Void free multi layer is much better than the cheap stuff, of course, but I've heard some of that (not BB) which was still significantly inferior to BB (tore it out of the back wall of a pair of cabinets that were otherwise BB because I could hear its distinct sonic contribution in fact), so the inherent strength and damping of the wood used is important, too, IMO.
For a step up in quality, I laminate 2 3/8" or 1/2" sheets of BB with some elastomeric adhesive such as a high solids contact cement.
I like to use plenty of (circumferential, where possible) edge bracing with plywood, or, better yet, 3" x 3/4" thick oak, with the option of sheathing the bracing material in aluminum or steel plate (all well damped, of course), so there is no unbraced span of more than about 15".
I've also used lead plate screwed and glued (with an elastomer) to solid hardwood cabinet panels, and that works, too.
I'd like to see a cite to that effect, since what I've posted is backed up by professionals in the wood products industry.
For that matter mdf is generally regarded as being more rigid than many plywoods, not less rigid. That is, until it cracks or crumbles (yeccch).
In any case, you are not addressing the points I made regarding uniformity and its effect on the resonant Q (which is apart from rigidity per se). And you apparently don't disagree with my observation that the resins used in MDF have poor acoustic properties.
For that matter mdf is generally regarded as being more rigid than many plywoods, not less rigid. That is, until it cracks or crumbles (yeccch).
In any case, you are not addressing the points I made regarding uniformity and its effect on the resonant Q (which is apart from rigidity per se). And you apparently don't disagree with my observation that the resins used in MDF have poor acoustic properties.
Well, you have not even started to address my points regarding MDF's uniformity and its effect on resonant Q and the resin's poor acoustic qualities, so I must assume you concede my points.
So, don't be offended if I regard rigidity as the end all and be all of a material's suitability for use in a speaker enclosure as a bit of a side issue here.
So, don't be offended if I regard rigidity as the end all and be all of a material's suitability for use in a speaker enclosure as a bit of a side issue here.
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