I know, plywood is resistant to cracking, has very good acoustical damping, etc.
And everyone seems to hate plastic boxes.
But the bloody WEIGHT... ughh.
I have a hard time believing that in 2018 there isn't finally some better alternative. Some kind of composite, or high tech plastic, or maybe a carbon-fiber sandwich.
Especially in the touring market, where weight is critical.
What's the deal? Is there anything worth trying, that might save a little weight, not resonate badly, and be no more than maybe 2-3X the cost of baltic Birch?
And everyone seems to hate plastic boxes.
But the bloody WEIGHT... ughh.
I have a hard time believing that in 2018 there isn't finally some better alternative. Some kind of composite, or high tech plastic, or maybe a carbon-fiber sandwich.
Especially in the touring market, where weight is critical.
What's the deal? Is there anything worth trying, that might save a little weight, not resonate badly, and be no more than maybe 2-3X the cost of baltic Birch?
I'm thinking in terms of "small" horns, like Art's Keystone, or Danley's TH112.
Take the latter. Very intriguing to me, but still about 145 lbs. I assume he's using a Neo magnet 12, so the cabinet itself must weigh at LEAST 130 lbs.
The Keystone, IIRC, is also around 145 lbs with an 18", so even if that were a ceramic driver......
I would imagine that very careful engineering could also replace the typical large bracing with something like aluminum channel, but the connect points would have to be really well worked out. And that still might no work.
We need that stuff they made the USS Enterprise out of.
Epoxy impregnated foam core as used in surfboards, boats and airplanes works well, but is a mess to work with, and more than 2-3X the cost of Baltic Birch. First saw it used in the early 1980's for speakers. Do a cost study on surfboards and you'll see why it's never gained much traction in the touring business.
You could buy a trailer and a ramp for a lot less cost, and save a lot of lifting and loading work and effort.
The USS Enterprise was a steel aircraft carrier. That said, it probably has a better enclosed volume to weight than the average sub cabinet.We need that stuff they made the USS Enterprise out of.
The Starship Enterprise was made from Unobtanium, IIRC.
That's the stuff you seem to be looking for ;^)
For touring use, BB and batten joints is the way, far far tougher than composite wrt puncture / de-lamination when dropped unless the laminate / pocket depth is of the correct dimensions.
Fwiw I do composites for a living:
Surfboards are dirt cheap wrt material cost, what you actually pay for is highly skilled labour - 6ft 6in basic board kit is £120, finished product £300 as a blond (no colour) and that's selling meself short by £75.
The spec of a racing sail craft hull of about 40ft or better yet 'nearly' that of a single seat race car tub would be ideal for a speaker cab.*
Aerospace is a different league of requirements....
BB all the way and get help lifting
*If the design is known, a 'very rough bill' could be generated easily.
A decent 15mm ply box with neo drivers is very light.
Time to hit the gym perhaps? Or maybe your system is too large for a single person. Two people can manage a full size 18" front loaded horn with little effort. Transport design helps a lot also(trollies, dollies and sub enclosures with good 100mm castors etc)
For mid high boxes, modifying generic plastic cabs has given me good results too. Something like a skytec JBL copy cabinet with quality neo drivers is a fairly cheap and light way to do things. Requires some knowledge and testing equipment etc to get right but works well.
Lifting techniques can be a real help, simple stuff like laying a 15' and horn cab on its back, insert the tripod and then 'stand' the whole thing up instead of trying to lift a speaker onto an already standing tripod. Like this video
YouTube
Time to hit the gym perhaps? Or maybe your system is too large for a single person. Two people can manage a full size 18" front loaded horn with little effort. Transport design helps a lot also(trollies, dollies and sub enclosures with good 100mm castors etc)
For mid high boxes, modifying generic plastic cabs has given me good results too. Something like a skytec JBL copy cabinet with quality neo drivers is a fairly cheap and light way to do things. Requires some knowledge and testing equipment etc to get right but works well.
Lifting techniques can be a real help, simple stuff like laying a 15' and horn cab on its back, insert the tripod and then 'stand' the whole thing up instead of trying to lift a speaker onto an already standing tripod. Like this video
YouTube
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A great question and one I've pondered recently*. Bet heavy cabinets really fool folks into swearing they sound more solid than light cabinets; an illusion that's hard to shake.
But first, as far as materials per se, hard to beat the various virtues of wood in the acoustic universe. In addition to BB, there're hardwood dowels that are light but very strong. And in Canada, we have discarded hockey sticks that support a major industry of making kitchen cutting boards.
But like with motorcycle mufflers, a dozen trade-offs when you get to actual design. The "suspension" is the basic datum. From that, you can judge pressures to be contained and how large are the unsupported surfaces, as freddi posted. But you have to do that in light of your tolerance for spurious box motions.
Beyond the straightforward design issues (including cost) is the question of your cleverness in devising bracing and your resources for accomplishing sophisticated designs.
And so on.
B.
* it's an awful acoustical material, but I'm thinking of using celotex ceiling panels as partitions inside a box
But first, as far as materials per se, hard to beat the various virtues of wood in the acoustic universe. In addition to BB, there're hardwood dowels that are light but very strong. And in Canada, we have discarded hockey sticks that support a major industry of making kitchen cutting boards.
But like with motorcycle mufflers, a dozen trade-offs when you get to actual design. The "suspension" is the basic datum. From that, you can judge pressures to be contained and how large are the unsupported surfaces, as freddi posted. But you have to do that in light of your tolerance for spurious box motions.
Beyond the straightforward design issues (including cost) is the question of your cleverness in devising bracing and your resources for accomplishing sophisticated designs.
And so on.
B.
* it's an awful acoustical material, but I'm thinking of using celotex ceiling panels as partitions inside a box
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.I’m an electric bassist and build most of my own gear. I also have fibromyalgia syndrome (25 years now), so lightweight gear is paramount to me. I went Class D in my bass amp heads years ago because 500 watts at under two kilos is a no brainer. Even with neo magnets I can’t find a 4x10” cab that’s under 22 kg and as I’m not an A list or 1st call session player, my gigs don’t pay enough to hire a roadie. I recall that up to about 15 years ago that Gallien Krueger had a Class AB solid state 150 watt combo with a neo magnet 12” bass driver+ tweeter in a fiberglass baffled (I read that as stuffed) sheet metal cabinet that sounded decent and weighed in at just under 13 kg. I’m not sure why they DCd the product other than poor sales and I’m not sure why it didn’t sell. It seems to me that the idea is worth revisiting with a Class D amp and a pair of neo drivers with a 500 watt output. As I see no one doing this, I guess I’ll build my own and see if I can get something in the sub 15 kg wt class, unless someone here is aware of such a product. BTW, when I say build my own, I mean including the Class D amp from scratch. They aren’t that difficult to design.
Another way might be to use two dissimilar materials, bonded together. (A good plastic, bonded to ?? ) - Carbon fiber again comes to mind. The idea is that, since each material has a different resonant frequency, they theoretically will cancel each other out a little bit. - Like how studio windows are always made from 2 different thicknesses of glass, one pane on each side, and walls are often two different thicknesses of sheet rock, glued together.
But would that work with a speaker cabinet? - And then I suppose you have to worry about vibrational flex. It's certainly beyond my realm of knowledge.
(Most things are. )
But would that work with a speaker cabinet? - And then I suppose you have to worry about vibrational flex. It's certainly beyond my realm of knowledge.
(Most things are.
)
... I seem to remember a few alternate sheets of glass fibre/carbon fibre was just about bullet proof (really!). They use it on some war helicopters I think (memory and all that).
Maybe one could use a thin 6mm (or even thinner?) sheet of ply as a structural starting point, and have glass/carbon/glass/carbon on top, no more, it is possible that would be enough.
Maybe one could use a thin 6mm (or even thinner?) sheet of ply as a structural starting point, and have glass/carbon/glass/carbon on top, no more, it is possible that would be enough.
Case in point. This material should have some role on a lighter weight cabinet material. It definitely offers some substance as an adequately strong material as it is being used in this pictured example that is within the link below.
New and Cool: Enki USA AMG-2 Guitar Case - Guitar World
New and Cool: Enki USA AMG-2 Guitar Case - Guitar World
Here are options I've considered (units all metric, prices & links all Australian, all panels 1200*2400mm)
birch ply as the default 18mm panel:
$200 (we are in the wrong hemisphere for birch, so it is overpriced here)
~36kg
Birch Premium Plywood | Plyco
Alu sandwich panel:
(20mm thick, 0.5mm face layers)
$344
~11.5kg
VENTURELITE 2020 - PanelMate
Note: joining and sealing ends would add weight & cost
DIY sandwich panels using Extruded Polystyrene (XPS) as the core, braceply as the skin:
$70-100 (depending on ply grade and glue used)
~17.5kg
Knauf Insulation 1200 x 600 x 30mm XPS Multi-Use Foam Board
2440 x 1200mm 4mm F27 Hardwood Plybrace | Bunnings Warehouse
Note: most of this weight is from the ply, a thinner skin (e.g. fibreglass or resin soaked Ram Board) could give a much lighter box.
Other: various daft schemes discussed in this thread (some not suited to horns, but may prompt more ideas):
Alu honeycomb panel
If you need to built some less massive speakers then have you considered balsa core panels?
This is what race yacht builders use as the next step up from ply, not too much more expensive but substantially less heavy.
It is manufactured in production line volume for the marine industry so there are economies of scale and the price reflects this.
Panels are available with thin timber skins, which makes it easy to work.
Then laminate a Kevlar or carbon fibre skin for structural unity.
It should be stiffer and more resistant to dents and knocks than sheet metal.
Best wishes
David
Hollowboy, have you checked to see if those materials would work, in terms of vbration?
I started this thread as just a theoretical interest, but the 2 subwoofer designs I'm currently considering (Art's slim Keystone and my own 4X10" PPSL BR concept) will both be a bit heavier than I think I can deal with. (Stairs being the main issue, so this is now a serious quest for me. If an extra 3-400 per sub could save me, say 20 lbs, that would be the bargain of the year.
That Aluminum stuff is insanely expensive, though, and imagine making a cut mistake?
I like your DIY panels idea, not sure what glue would work best, though. It would also require (I assume) full-length reinforcement pieces inside, to screw the whole thing together, as you couldn't use rabbit joints. So, a slight loss of internal volume.
Still, This definitely merits some investigation.
----------------
I also saw this today, when searching my old notes:
QSC ISIS dual 15” "modified Horn" (as they call it) sub. It's made of a carbon fiber composite, and this was back in 2004!
https://www.qsc.com/resource-files/...ed/isis/i-215pcm/q_spk_isis_i215pcm_specs.pdf
- The bloody thing is still 175 pounds, though!
Where the heck would a DIY guy buy small quantities of this stuff?
I started this thread as just a theoretical interest, but the 2 subwoofer designs I'm currently considering (Art's slim Keystone and my own 4X10" PPSL BR concept) will both be a bit heavier than I think I can deal with. (Stairs being the main issue, so this is now a serious quest for me. If an extra 3-400 per sub could save me, say 20 lbs, that would be the bargain of the year.
That Aluminum stuff is insanely expensive, though, and imagine making a cut mistake?
I like your DIY panels idea, not sure what glue would work best, though. It would also require (I assume) full-length reinforcement pieces inside, to screw the whole thing together, as you couldn't use rabbit joints. So, a slight loss of internal volume.
Still, This definitely merits some investigation.
----------------
I also saw this today, when searching my old notes:
QSC ISIS dual 15” "modified Horn" (as they call it) sub. It's made of a carbon fiber composite, and this was back in 2004!
https://www.qsc.com/resource-files/...ed/isis/i-215pcm/q_spk_isis_i215pcm_specs.pdf
- The bloody thing is still 175 pounds, though!
Where the heck would a DIY guy buy small quantities of this stuff?
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