I've heard the LS3/5As - albeit a long time ago - and at the time wasn't very enthusiastic about them. That could have been the source equipment or the particular version (or the fact that I've never heard a speaker with Bextrene drivers that I've liked). However, the research in the original paper still holds for cabinet construction and was one of the first attempts to quantify the effects objectively.
There is a product that is used in commercial construction called"Blueskin"- it's used as a air barrier/vapor barrier on concrete block walls. It comes in rolls up to 48" wide.
I mention this because it has amazing damping qualities. It is thin, fairly light and sticky as hell.
Made from rubberized asphalt, it stretches and is pliable, unlike the heavy stinky asphalt impregnated felt.
I would like to use this as the adhesive in my CLD, but it has a layer of polyethelene (blue, of course) on it's face.
I wonder if I were to use contact cement to glue the face side on, then let the sticky side attach to the outer panel?
Worth thinking about...
I mention this because it has amazing damping qualities. It is thin, fairly light and sticky as hell.
Made from rubberized asphalt, it stretches and is pliable, unlike the heavy stinky asphalt impregnated felt.
I would like to use this as the adhesive in my CLD, but it has a layer of polyethelene (blue, of course) on it's face.
I wonder if I were to use contact cement to glue the face side on, then let the sticky side attach to the outer panel?
Worth thinking about...
There is another construction technique I'd be interested in comments on. This involves bonding 12mm insulation board to contiboard (veneered chipboard - usually 15mm thick). The construction makes a light, rigid panel. It's a variation of an early BBC technique and promoted by Russ Andrews
I had a pair of 35L sealed enclosures built this way and thought the overall system sounded good. When I sold them, the buyer played them (loud) and they sounded much better than his reflex-loaded, plaster and aluminium commercial enclosures using similar drivers (caveat that the loading was different, of course). The panel resonances were there but didn't seem intrusive and the insulation board gave extra HF damping on the cabinet surfaces. It certainly made for a lighter enclosure to move around.
I didn't try a comparison cabinet in 22mm ply or MDF. Anyone else tried this technique?
I had a pair of 35L sealed enclosures built this way and thought the overall system sounded good. When I sold them, the buyer played them (loud) and they sounded much better than his reflex-loaded, plaster and aluminium commercial enclosures using similar drivers (caveat that the loading was different, of course). The panel resonances were there but didn't seem intrusive and the insulation board gave extra HF damping on the cabinet surfaces. It certainly made for a lighter enclosure to move around.
I didn't try a comparison cabinet in 22mm ply or MDF. Anyone else tried this technique?
Wow, long thread, I been reading it on and off, but I confess I haven't read it all (55 pages, that's a lot).
Here is an idea that I've been toying with. To some extent we can wish for whatever we want, but in the end, we have to take whatever is available in our area.
Recently I went to our local Home Depot and asked if they could order me some birch (or any wood) veneered MDF. The guy looked at me like I was crazy. He dragged out several books, and didn't find it, so he took my name and phone number, and said he would call me; he didn't.
So, I toyed with this idea. How about building speakers out of good quality available plywood, but lining the insides (left, right, top, bottom) with 1/2" mdf? (screwed and glued)
That should make the sides ridged, give nice acoustic properties.
So, what do you think? A waste of time, or does this have some potential?
Can it potentially overcome or compensate for flaws in standard, but good, quality plywood?
Also, I could never quite understand the concept of routing down into a 3/4" piece of MDF to mound the speakers (roughly) flush. That would mean your mounting your speakers in 1/2" to a very best 5/8" MDF. That seem pretty thin.
I think if I were going to do that, I would laminate 1/2" MDF to 3/4" MDF then route down into that, in which case I would have close to an INCH to fasten my speakers to.
Now, I realize I can do anything I want; the question isn't can I do it, the question is, is either of these a good idea?
Steve/BlueWizard
Here is an idea that I've been toying with. To some extent we can wish for whatever we want, but in the end, we have to take whatever is available in our area.
Recently I went to our local Home Depot and asked if they could order me some birch (or any wood) veneered MDF. The guy looked at me like I was crazy. He dragged out several books, and didn't find it, so he took my name and phone number, and said he would call me; he didn't.
So, I toyed with this idea. How about building speakers out of good quality available plywood, but lining the insides (left, right, top, bottom) with 1/2" mdf? (screwed and glued)
That should make the sides ridged, give nice acoustic properties.
So, what do you think? A waste of time, or does this have some potential?
Can it potentially overcome or compensate for flaws in standard, but good, quality plywood?
Also, I could never quite understand the concept of routing down into a 3/4" piece of MDF to mound the speakers (roughly) flush. That would mean your mounting your speakers in 1/2" to a very best 5/8" MDF. That seem pretty thin.
I think if I were going to do that, I would laminate 1/2" MDF to 3/4" MDF then route down into that, in which case I would have close to an INCH to fasten my speakers to.
Now, I realize I can do anything I want; the question isn't can I do it, the question is, is either of these a good idea?
Steve/BlueWizard
Wow what a post. andI have read most of it. I have decided to make my cabinets of wood. Now which wood? Is the cabinet part of the sound? Is density important, or should it be musical like a guitar? Here is a guitar link www.jemsite.com/jem/wood.htm
When you say 'wood' I assume you mean solid wood. I think you will find that you are restricted in this area by both availability and budget. Enough solid wood to make cabinets is going to be expensive, if you can find someone to supply it to you.
Solid wood presents another problem, you are not going to be able to buy it in sheets. You' have to by standard dimensional boards, and glue them together. That means the edge gluing to make the boards wide enough, should be tongue and groove, or a lap joint. A 'lap joint' means you create a lip along the edge of each piece needing to be glued by cutting away half the material, then you flip one piece over and glue the lips together. That creates more surface area to hold the joint together.
It is possible to use standard butt joints, and it will probably hold up fine, but it won't be as strong.
Also, there is the problem of moisture. If the wood hasn't been fully cured and kiln dried, there is likely to be some warping, splitting, and cracking. Still, furniture is made this way, or at least it used to be, and it stands up fine.
If you can find the wood and you can afford it, and you are a careful builder, you should be fine. Personally, I think I would try to find already veneered MDF or veneered plywood. You'll get stable wood with nice grain and no hassels.
Still, don't let me talk you out of it. If you really are interested in trying solid wood, go for it.
Another material I wonder if people have tried. You could take MDF and build your basic cabinet, then cover it with hardwood flooring. They make 'easy' simulated hardwood flooring in panels 4 feet long by a foot wide by about 1/8" to 1/4" thick. The grain is clean, both sides are perfectly flat, the pieces fit together perfectly, and with some care, you shouldn't have a problem gluing them to your cabinet. Ranging from US$1.70 to $4.00 per square foot; the stuff you would likely to be use would be in the $1.70 to $2.50 per sq.ft range.
Just curious if anyone has considered or tried this idea.
Steve/BlueWizard
Solid wood presents another problem, you are not going to be able to buy it in sheets. You' have to by standard dimensional boards, and glue them together. That means the edge gluing to make the boards wide enough, should be tongue and groove, or a lap joint. A 'lap joint' means you create a lip along the edge of each piece needing to be glued by cutting away half the material, then you flip one piece over and glue the lips together. That creates more surface area to hold the joint together.
It is possible to use standard butt joints, and it will probably hold up fine, but it won't be as strong.
Also, there is the problem of moisture. If the wood hasn't been fully cured and kiln dried, there is likely to be some warping, splitting, and cracking. Still, furniture is made this way, or at least it used to be, and it stands up fine.
If you can find the wood and you can afford it, and you are a careful builder, you should be fine. Personally, I think I would try to find already veneered MDF or veneered plywood. You'll get stable wood with nice grain and no hassels.
Still, don't let me talk you out of it. If you really are interested in trying solid wood, go for it.
Another material I wonder if people have tried. You could take MDF and build your basic cabinet, then cover it with hardwood flooring. They make 'easy' simulated hardwood flooring in panels 4 feet long by a foot wide by about 1/8" to 1/4" thick. The grain is clean, both sides are perfectly flat, the pieces fit together perfectly, and with some care, you shouldn't have a problem gluing them to your cabinet. Ranging from US$1.70 to $4.00 per square foot; the stuff you would likely to be use would be in the $1.70 to $2.50 per sq.ft range.
Just curious if anyone has considered or tried this idea.
Steve/BlueWizard
Lured to this thread from another, looked at some measurements, and I must first admit I had not tempted to build and ultimate enclosure. But perhaps I should start on such attempt. Not going into specific material, I think there are a few things that possibly is worth considering:
1. Stiffness: This is good to prevent low frequency resonance, but not always good for mid and high.
2. Damping: This is one way of dissipating energy transferred to the enclosure, and is very important for faster decay of sound generated from the enclosure panels.
3. Mode disrupters: This is usually varying mass and/or stiffness in a panel to prevent build up of energy storage, which also makes vibration easier to be dampped.
Talk about ultimate? Dream project would be crystal or diamond structure with gold panels.
1. Stiffness: This is good to prevent low frequency resonance, but not always good for mid and high.
2. Damping: This is one way of dissipating energy transferred to the enclosure, and is very important for faster decay of sound generated from the enclosure panels.
3. Mode disrupters: This is usually varying mass and/or stiffness in a panel to prevent build up of energy storage, which also makes vibration easier to be dampped.
Talk about ultimate? Dream project would be crystal or diamond structure with gold panels.
Not true: if your joints are straight and square, so that there are no gaps in the butt joint, the glue joint will be stronger than the wood.
Your issue will be that the solid wood panels will expand and contract in width with humidity changes; and this is the case no matter what kind of joints you glue the panel up with.
Regards.
Aengus
Hi Guys.
Well, after many months of fiddling around, have been working with Peter Comeau of Heybrook fame to produce a composite board for commercial loudspeakers. It can be manufactured in-house using 3 different types of board i.e. chipboard, plywood and MDF.
Using an accelerometer linked to MLSSA, we found that MDF on it's own has a very strong sonic signature and it's right where you DON'T want it. In the midrange. Plywood doesn't have this but because of the way it is laminated, acts like an ABR presenting little if no acoustic loading to the driver at low frequencies. Chipboard exhibits none of the above but, on it's own gives a somewhat 'woolly' presentation to the sound.
By using a mixture of all 3, we were able to drive the panel resonance down below the signal level of the drivers. Of course you can still measure it. You can't just DUMP all of that energy but you can't hear it.
Paul Messenger wrote about this material last year in Stereophile.
We won't be using single board again.
Ricky.
Well, after many months of fiddling around, have been working with Peter Comeau of Heybrook fame to produce a composite board for commercial loudspeakers. It can be manufactured in-house using 3 different types of board i.e. chipboard, plywood and MDF.
Using an accelerometer linked to MLSSA, we found that MDF on it's own has a very strong sonic signature and it's right where you DON'T want it. In the midrange. Plywood doesn't have this but because of the way it is laminated, acts like an ABR presenting little if no acoustic loading to the driver at low frequencies. Chipboard exhibits none of the above but, on it's own gives a somewhat 'woolly' presentation to the sound.
By using a mixture of all 3, we were able to drive the panel resonance down below the signal level of the drivers. Of course you can still measure it. You can't just DUMP all of that energy but you can't hear it.
Paul Messenger wrote about this material last year in Stereophile.
We won't be using single board again.
Ricky.
Concrete
I am currently in the process of building molds with which to pour a pair of subwoofers and some tower cabinets from a concrete mix consisting of cement, sand,, nylon fiber, and very fine ground rubber (1.5" wall thickness) . internal bracing will be birch ply. Experimentation has shown the stone and rubber components of the mix to be very self damping. We shall see how it turns out. My trial run sub box of off-the-shelf crack-resistant concrete seems extremely solid and once the birch cross braces go in, i think there will be no trace of hollowness to it.
Experimentation is all part of the DIY game, isnt it?
I am currently in the process of building molds with which to pour a pair of subwoofers and some tower cabinets from a concrete mix consisting of cement, sand,, nylon fiber, and very fine ground rubber (1.5" wall thickness) . internal bracing will be birch ply. Experimentation has shown the stone and rubber components of the mix to be very self damping. We shall see how it turns out. My trial run sub box of off-the-shelf crack-resistant concrete seems extremely solid and once the birch cross braces go in, i think there will be no trace of hollowness to it.
Experimentation is all part of the DIY game, isnt it?
Suggest you use a plant fibre like Hemp or Flax instead of Nylon as bonding ratio is far superior, and include some sort of reo mesh.
They've been doing this fibre content sort of thing (without the crumbed rubber) for thousands of years and many of the structures are still in use.
Slow cure is best for these and I fill the curing concrete chambers with water for about a week for the mix with the "Multibond" additives in it. I'm still playing with the mix that they make the concrete boats out of - really sticky goo, even with the extra release agents!
Best boxes "never heard" are in concrete.
They've been doing this fibre content sort of thing (without the crumbed rubber) for thousands of years and many of the structures are still in use.
Slow cure is best for these and I fill the curing concrete chambers with water for about a week for the mix with the "Multibond" additives in it. I'm still playing with the mix that they make the concrete boats out of - really sticky goo, even with the extra release agents!
Best boxes "never heard" are in concrete.
Yeah, maybe true - not so concerned about the strength so much (with the mesh wire and frame) but with developing as "inert" a material as possible for the "chamber", and then there are the questions about CLD and backwave elimenation and linear freq/power attenuation, etc, etc
Pity we can't begin with a linear freq and phase response ......
Playing with that "Acoustica" stuff ("echostop" and "acoustiflex") for the inner walls and baffles - hence all the frustrating concrete experiments!
Had a look at that "Descrete" idea from Zeobond - hard to get much info from them.
there are a few of those horns made of that "Flowstone" material - weird stuff - more chemicals than concrete.
I see you've moved down to Geelong - nice place.
Pity we can't begin with a linear freq and phase response ......
Playing with that "Acoustica" stuff ("echostop" and "acoustiflex") for the inner walls and baffles - hence all the frustrating concrete experiments!
Had a look at that "Descrete" idea from Zeobond - hard to get much info from them.
there are a few of those horns made of that "Flowstone" material - weird stuff - more chemicals than concrete.
I see you've moved down to Geelong - nice place.
Hello!
I consider using boards made of shreddered and compressed PU hard foam.
http://www.phonotherm.com
From knocking on them they are really dead, but they are a bit more floppy than the usual materials. I would use no additional wool, etc in the box.
I would use it in the midrange only because its floppiness doesn´t allow the use where constant volume is critical (BR). What do you think about it?
Oliver
I consider using boards made of shreddered and compressed PU hard foam.
http://www.phonotherm.com
From knocking on them they are really dead, but they are a bit more floppy than the usual materials. I would use no additional wool, etc in the box.
I would use it in the midrange only because its floppiness doesn´t allow the use where constant volume is critical (BR). What do you think about it?
Oliver
James have you tried the mixture of shredded newspaper with PVA and Plaster of Paris ?? sets like a rock and very inert.
I soak the shredded paper in PVA glue and then add plaster and trowel it on, usually inside to seal all the joins and deaden up cheap chip-board boxes
http://cgi.ebay.com.au/ws/eBayISAPI.dll?ViewItem&ssPageName=STRK:MEWAX:IT&item=330318978882
like these ones Missus won't let me spend the petrol money to go pick them up tho!!
I soak the shredded paper in PVA glue and then add plaster and trowel it on, usually inside to seal all the joins and deaden up cheap chip-board boxes
http://cgi.ebay.com.au/ws/eBayISAPI.dll?ViewItem&ssPageName=STRK:MEWAX:IT&item=330318978882
like these ones Missus won't let me spend the petrol money to go pick them up tho!!
Oliver,
I think there's a US company that's building speakers from a very similar material and they seem to be rather happy with the results.
MD55,
Haven't done anything like that - once had a chalk and concrete really solid horn that was quite dead, but nothing like the "goo" that you're looking at - sounds as tho it might be very absorbant. Simple enough to try, especially for some of those really light panel designs that surprisingly sound rather good.
There is a French speaker that actually use different sized really thin panels and vary the loading on them to control the radiated energy from all the surfaces - a musical instrument in itself like a violin, really - very highly regarded - can't remember the name, damnit!
A benefit of moulding in concrete, etc is that the sound projects from curved shapes far better than flat surfaces.
Just to add some spice to the discussion, there's a guy that uses a variation of the EnABL patterns on the edge perimeters of his boxes to good effect - no idea how it works but others have confirmed the results - weird stuff!!
I think there's a US company that's building speakers from a very similar material and they seem to be rather happy with the results.
MD55,
Haven't done anything like that - once had a chalk and concrete really solid horn that was quite dead, but nothing like the "goo" that you're looking at - sounds as tho it might be very absorbant. Simple enough to try, especially for some of those really light panel designs that surprisingly sound rather good.
There is a French speaker that actually use different sized really thin panels and vary the loading on them to control the radiated energy from all the surfaces - a musical instrument in itself like a violin, really - very highly regarded - can't remember the name, damnit!
A benefit of moulding in concrete, etc is that the sound projects from curved shapes far better than flat surfaces.
Just to add some spice to the discussion, there's a guy that uses a variation of the EnABL patterns on the edge perimeters of his boxes to good effect - no idea how it works but others have confirmed the results - weird stuff!!
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