i was in my car today and an idea popped into my head... wouldnt it be cool to mount a midrange driver inside a bored out bowling ball? i figure, cant get much more dense that that, and there would be almost NO resonance.
then i thought, wait, isnt a bowling ball just pure resin? why not make an entire cabinet out of it.
if you made a typical loudspeaker (floorstander) cabinet from resin, it would be MUCH denser and heavier than wood or MDF, it would have a lot less resonance, be fairly easy to make into different shapes, and very flexible in design.
is there downsides to this? cost really isnt a factor. it would almost be cheaper than MDF if you could just plan out the molds right. foam is cheap, and so is resin. finishing it would be a dream. you could just sand and polish it, and basically paint it. or, just dye it before it hits the molds.
seems to me that a very complex structure with vented ports, chambers, etc, could be made without too much effort with resin.
anyone else have any comments on this?
then i thought, wait, isnt a bowling ball just pure resin? why not make an entire cabinet out of it.
if you made a typical loudspeaker (floorstander) cabinet from resin, it would be MUCH denser and heavier than wood or MDF, it would have a lot less resonance, be fairly easy to make into different shapes, and very flexible in design.
is there downsides to this? cost really isnt a factor. it would almost be cheaper than MDF if you could just plan out the molds right. foam is cheap, and so is resin. finishing it would be a dream. you could just sand and polish it, and basically paint it. or, just dye it before it hits the molds.
seems to me that a very complex structure with vented ports, chambers, etc, could be made without too much effort with resin.
anyone else have any comments on this?
A few thoughts...
1) Your enclosures would be very heavy...
2) Building the mould would be more complicated than building the box initially from wood, and it all needs to be finished very well to give a good surface to the resin. Also resin gives off very large amounts of heat whilst curing, so your mould design needs to take this into account.
3) Estimating from the price of resin in the UK I think you might find it is very expensive for the quantity you would need.
4) To prevent the cabinet becoming brittle you may need to load it with fibre in such a large and complicated structure.
But bearing all of that in mind, my favorite speakers of all time, the B&W Nautilus use resin for the cabinets, because they would be just about impossible to make from wood.
So, in conclusion, if you have the time and money, go for it, but as always it is probably worth building a test piece first, maybe a mid enclosure, or a small full range box.
Good luck
1) Your enclosures would be very heavy...
2) Building the mould would be more complicated than building the box initially from wood, and it all needs to be finished very well to give a good surface to the resin. Also resin gives off very large amounts of heat whilst curing, so your mould design needs to take this into account.
3) Estimating from the price of resin in the UK I think you might find it is very expensive for the quantity you would need.
4) To prevent the cabinet becoming brittle you may need to load it with fibre in such a large and complicated structure.
But bearing all of that in mind, my favorite speakers of all time, the B&W Nautilus use resin for the cabinets, because they would be just about impossible to make from wood.
So, in conclusion, if you have the time and money, go for it, but as always it is probably worth building a test piece first, maybe a mid enclosure, or a small full range box.
Good luck
actually, ive done some checking...
weight wouldnt be a HUGE issue. im looking at using areospace resin. its lightweight (relatively), strong (not brittle like you say), and its low temp curing. plus, a 5-gallon bucket of the stuff is like $50 or so. molds are easy. i know a guy who makes all sorts of parts for his model airplanes from it. you just use styrafoam blocks, cut out the shapes, and pour it. a lot of work would go into the design though... if you were talented enough, you could make one mold for the speaker, but you would probably need multiple ones. but with resin, you can join then easily, and chemically, it would be one peice once fused.
and from what i understand, sanding and finishing it is as easy sanding wood. you can get a polished mirror finish from it without much effort.
lastly, if everyone here uses 1/2" or 3/4" MDF, if you used that same thickness of resin, it would be about 4x as dense. sure it would be heavy, but isnt that the point? the meridian dsp8000's weigh in at like 500 pounds EACH. its a resin/granite thing that the cabinet is made out of. i dont see weight as a downside, except if it got absurdly heavy.
i think ill take your advice and just make a prototype mini-monitor or something first, then maybe look into doing some towers. a mini-monitor or bookshelf should really only need about 5 gallons of resin. so the cost would be nice.
correct me if im wrong here, but would i need internal bracing if i made the cabinet at least 3/4" thick with resin? wouldnt that be more than enough to warrant bracing?
oh, and btw, the watt cubbII's use high density MDF AND resin as their cabinets. i think the baffles are mdf, and the cabinet itself was resin. it seems like the big boys use resin instead of wood... even the b&w 800, 801's use resin for the midrange enclosure.
weight wouldnt be a HUGE issue. im looking at using areospace resin. its lightweight (relatively), strong (not brittle like you say), and its low temp curing. plus, a 5-gallon bucket of the stuff is like $50 or so. molds are easy. i know a guy who makes all sorts of parts for his model airplanes from it. you just use styrafoam blocks, cut out the shapes, and pour it. a lot of work would go into the design though... if you were talented enough, you could make one mold for the speaker, but you would probably need multiple ones. but with resin, you can join then easily, and chemically, it would be one peice once fused.
and from what i understand, sanding and finishing it is as easy sanding wood. you can get a polished mirror finish from it without much effort.
lastly, if everyone here uses 1/2" or 3/4" MDF, if you used that same thickness of resin, it would be about 4x as dense. sure it would be heavy, but isnt that the point? the meridian dsp8000's weigh in at like 500 pounds EACH. its a resin/granite thing that the cabinet is made out of. i dont see weight as a downside, except if it got absurdly heavy.
i think ill take your advice and just make a prototype mini-monitor or something first, then maybe look into doing some towers. a mini-monitor or bookshelf should really only need about 5 gallons of resin. so the cost would be nice.
correct me if im wrong here, but would i need internal bracing if i made the cabinet at least 3/4" thick with resin? wouldnt that be more than enough to warrant bracing?
oh, and btw, the watt cubbII's use high density MDF AND resin as their cabinets. i think the baffles are mdf, and the cabinet itself was resin. it seems like the big boys use resin instead of wood... even the b&w 800, 801's use resin for the midrange enclosure.
Hiya
What you are proposing has been done many times commercially, with various amounts of success (financially). Currently in the US a firm doing business as Poly-crystal does small runs of speaker cabinets for constructors.
US Enclosures at one point had hollow resin spheres available to the DIY community, though with a reputation of poor service.
Could very well be a fun DIY-Audio project!
The weight issue of the resin may be addressed by adding glass balloons to the resin mix, these are often sold as "micro-balloons".
When choosing resin care must be exercised to assure compatibility with the foam core. Not only can heat cause problems but some castable materials will attack plastic foam.
Cyclotronguy
What you are proposing has been done many times commercially, with various amounts of success (financially). Currently in the US a firm doing business as Poly-crystal does small runs of speaker cabinets for constructors.
US Enclosures at one point had hollow resin spheres available to the DIY community, though with a reputation of poor service.
Could very well be a fun DIY-Audio project!
The weight issue of the resin may be addressed by adding glass balloons to the resin mix, these are often sold as "micro-balloons".
When choosing resin care must be exercised to assure compatibility with the foam core. Not only can heat cause problems but some castable materials will attack plastic foam.
Cyclotronguy
cowanrg said:
Worth a try. Another easier option would be to make a shell out of 1/2" mdf, and then just layer the resin inside that, making a hybrid speaker. You could get a really solid cabinet from this. I have a friend that used to make car subwoofer cabinets this way. Sure, this wouldn't give you an impressive looking speaker, and would look like a normal box, but I would imagine that it would be one rigid box speaker.
--
Brian
Are all of the B&W speakers using resin Transmission Line speakers? I think there would be a problem in small sealed enclosures made out of resin because the energy inside the speaker has to go somewhere and that somewhere is usually out the speaker cone. TL's don't really suffer this problem so they can benefit from the most dense cabinet possible. I don't know how vented boxes are affected by this. Dense wood is generally the best thing to use in sealed speakers IMO because it absorbs enough of the energy into the cabinet walls without transmitting it through the walls therefore not requiring that the energy escape through the driver cone. I did a little research on this during the summer in my acoustics class, but never really came to a conclusion of whether the benefits of the resin enclosure was worth it. (This does not apply to TL's because it obviously was better). Hope you can follow that. Has anyone done any experiments along these lines?
Austin
Austin
Hi cowanrg,
I've been considering a similar project as well-- could you please post the specific types of 'aerospace resin' you were investigating, and where they can be purchased?
Although weight is apparently not a consideration for you, I wouldn't mind a lighter, more easily portable speaker (if it would not compromise sound quality).
It should be easy to cast a few small sheets with various fillers to reduce weight and/or increase dampling and then measure the results. Could be an interesting project...
Thanks,
Mark
I've been considering a similar project as well-- could you please post the specific types of 'aerospace resin' you were investigating, and where they can be purchased?
Although weight is apparently not a consideration for you, I wouldn't mind a lighter, more easily portable speaker (if it would not compromise sound quality).
It should be easy to cast a few small sheets with various fillers to reduce weight and/or increase dampling and then measure the results. Could be an interesting project...
Thanks,
Mark
sure, ill call my friend and ask him for a phone number or website of the place... supposedly its pretty lightweight yet very strong. might be something good for you. plus, keep in mind since its resin, you can make molds of any shape you want. so you can pretty much make it stronger by using interesting shapes and internal bracing. a 1/4" wall should be as non-resonant as MDF i would think... that could keep weight way down.
DIY Nautilus
Hello,
It is not so easy, but with some effort it is possible to build this
speaker from wood.
Here below are some pictures how it would go:
Best regards,
Kristijan Kljucaric
http://web.vip.hr/pcb-design.vip
Hello,
It is not so easy, but with some effort it is possible to build this
speaker from wood.
Here below are some pictures how it would go:
Best regards,
Kristijan Kljucaric
http://web.vip.hr/pcb-design.vip
Attachments
sorry to sabotage this thread, but you could always make stuff from fiberglass and polyester resin--i do this for car speakers for subs and tweet pods all the time.. cost is relatively cheap provided you buy in bulk at a marine store, rather than a home improvement store, and it takes a long time, but you can get amazing finishes and any shape imaginable.. its important to remember tho that fiberglass gets most of its strenght from curves and turns, so any straight panels must be made with MDF---the overall weigth will be a fraction of an mdf box, and the strength several times greater. here is some very basic tutorials i wrote on how to do it. in my tutorials i do not show how to finish a glassed surface but its pretty straight foward--fill pits with bondo, sand, glazing putting, sand, primer, continue sanding until 1000+ grit, then paint or finish accordingly.. doing so you can get a finish that looks like a fresh paint job on a brand new car.
http://web.njit.edu/~cas1383/proj/main
-chris
http://web.njit.edu/~cas1383/proj/main
-chris
Hi,
Best material is epoxy + kevlar (or carbon fibre). It does not crimp as much as polyester but it is more expensive. For weight you can load it with coarse sand, gravel or lead grit.
But back to the original question regarding mid compartments, have you ever considered a terracotta flour pot for it cowanrg?
Cheers
Best material is epoxy + kevlar (or carbon fibre). It does not crimp as much as polyester but it is more expensive. For weight you can load it with coarse sand, gravel or lead grit.
But back to the original question regarding mid compartments, have you ever considered a terracotta flour pot for it cowanrg?
Cheers
Resin would be interesting to try for prototyping horns. Foam molds could be made with CNC foam cutter. If the resin really prices out well this could turn out to be a great way of testing horn designs for not too much money. It’s got me curious about what it would cost to have the foam cut from DXF files.
I like the idea of using a resin- PMMA or polyester are good choices. One other approach is to load the resin with microspheres. There are some hollow ones available in a variety of diameters, with coupling agents already on them. The hollow jobbies could reduce mass while enhancing rigidity. And they'll reduce the cost.
Only handle microspheres wearing a respirator mask and gloves. Particulates can be dangerous to the lungs. Once microspheres are embedded in plastic, they're harmless, but loose, they present an inhalation hazard.
Pricing and a retail source for microspheres and other fillers:
http://www.mrfiberglass.com/fillersa.htm
Only handle microspheres wearing a respirator mask and gloves. Particulates can be dangerous to the lungs. Once microspheres are embedded in plastic, they're harmless, but loose, they present an inhalation hazard.Pricing and a retail source for microspheres and other fillers:
http://www.mrfiberglass.com/fillersa.htm
kristijan-k,
you made these enclosures out of wood???
**Incredible**
and i thought my 50hr+finishing solid wood horns are much work... (they are, compared to usual box stuff)
How long did it take you to make one?
do you have CAD-CAM (CNC) machinery to make the parts??
very impressive in any case!
Regards,
keyne
you made these enclosures out of wood???
**Incredible**
and i thought my 50hr+finishing solid wood horns are much work... (they are, compared to usual box stuff)
How long did it take you to make one?
do you have CAD-CAM (CNC) machinery to make the parts??
very impressive in any case!
Regards,
keyne
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