So then do you also agree with @birdbox on using just fiberglass, or do you think CF is still worth exploring?
Interesting. So would that combination make the material easier to work with as well?
I don't think I've ever seen sleeving before. Is it like the same sort of twill weave or something else?
Guess I got my next project 🤪
If I use sonotube, if I use it as the base for the composite, will it still have the structural advantages I'm looking for? I have read resin impregnated paper is strong, I just don't have experience with it. If it can be as strong or stronger than mdf then yeah I think that would be a nifty solution.
The highest excursion 8" subwoofers produce only tiny fraction of the SPL (sound pressure level) that commercial sound reinforcement subwoofers with multiple 18", 21", 24", or larger drivers.
The dual 8" would produce orders of magnitude less force- somewhat along the pressure difference between a boat hull and a deep sea submersible.
24/25mm/1" Baltic Birch with internal bracing has been found sufficient for cabinets 60"x60"x30" and larger using in excess of 20,000 (20kW) peak power.
For a small 2x8" enclosure, 5/8″ (15mm) Baltic Birch would be plenty rigid, past that thickness it would be hard to measure, much less hear any difference.
Any "mush" detected would (should) not be attributed to a well-braced enclosure.
An epoxy or polyester fiberglass construction could be made as stiff as Baltic Birch with less material thickness, saving some weight, while increasing building cost and complexity.
Using foam core can increase strength to weight ratios, but for a small enclosure increases size considerably.
I haven't used fiberglass for loudspeaker enclosure construction since the late 1970s, the cost vs benefit ratio just did justify it's use.
Other than cabinets built for outdoor use, fiberglass is seldom used in speaker cabinet construction any more.
Carbon fiber offers some further benefit in weight reduction over fiberglass, but is considerably more expensive and more difficult to work with.
The only role the advantages of carbon fiber in loudspeaker use merit it's adoption is as diaphragm material, particularly high frequency applications.
That said, even in that application, the cost vs audio benefit is marginal, and debatable.
Art
MDF is not strong or stiff by comparison to any plywood (or resin impregnated paper/cardboard), but it is heavy..
Thanks for coming by art 🙂
So then a 16"x~18" enclosure should have no problem. Sweet.
It seems there's always a toss up between density and rigidity. If I'm going for a lightweight enclosure though seems like composite is the way to go.
Last time I did was almost a decade ago doing pipe lagging so I know the feeling 😅
I can take a hit to weight as long as structural integrity is good. Actually I'm pretty curious about the weave @Moondog55 posted. A hybrid like that I would imagine is a bit easier to work with because of the combination of materials.
I had missed a post and assumed you wanted CF for the appearance. If not, back-burner that idea and consider
Regular E-glass. S- glass has improved stiffness (modulus of elasticity) and higher heat resistance but doesnt lay down quite as easily as eglass and won't buy you any improvements in performance for the application.
CF can indeed make a stronger, lighter structure but the final strength to weight ratio is highly dependent on the amount of resin left in the piece... less is more in this case. Hand layups require experience to hit the goldilocks region to maximize strength/weight. Most of us will leave too much resin in the piece, yielding a bit of increased stiffness with very little weight savings. Not enough of either to justify the added expense for an 8" sub.
The same goes for the use of hybrid fabrics in this case. The properties they bring to the table are simply not needed in a small sub enclosure and you'd never be able to tell one from the other via ABX testing.
All of that said, it doesn't cost much to play in this arena and armed with a small vacuum pump, much can be accomplished. Infusion isn't terribly costly to get into either, mainly relying on plastic tubing and the associated fittings to move resin around. The experience to choose fabric weight, weave, number of layers as well as the number of and placement of the infeed- outfeed tubing ports is the most important point.
Resin traps are $$ but that's about it until you want to produce aerospace quality parts.
Regular E-glass. S- glass has improved stiffness (modulus of elasticity) and higher heat resistance but doesnt lay down quite as easily as eglass and won't buy you any improvements in performance for the application.
CF can indeed make a stronger, lighter structure but the final strength to weight ratio is highly dependent on the amount of resin left in the piece... less is more in this case. Hand layups require experience to hit the goldilocks region to maximize strength/weight. Most of us will leave too much resin in the piece, yielding a bit of increased stiffness with very little weight savings. Not enough of either to justify the added expense for an 8" sub.
The same goes for the use of hybrid fabrics in this case. The properties they bring to the table are simply not needed in a small sub enclosure and you'd never be able to tell one from the other via ABX testing.
All of that said, it doesn't cost much to play in this arena and armed with a small vacuum pump, much can be accomplished. Infusion isn't terribly costly to get into either, mainly relying on plastic tubing and the associated fittings to move resin around. The experience to choose fabric weight, weave, number of layers as well as the number of and placement of the infeed- outfeed tubing ports is the most important point.
Resin traps are $$ but that's about it until you want to produce aerospace quality parts.
Infusion or Resin Transfer Molding uses vacuum to draw resin into, through and out of the bagged piece to control the distribution and amount of resin in the final product
Yeah I worry about aesthetic later. First gotta design the damn thing lol. At this point I'm not even sure how/what finish to use, especially if the outer shell is composite.
Its actually 2 subs in the enclosure. It's for an active speaker I'm making. I figured with a thin outer layer, I could make a CLD sandwich between the outer layer and the inner skeleton. That's why I was looking to CF in the first place.
What about for the sonopan? Would that be worth exploring?
Theeeeeeeeeeen maybe I should look around for an experienced set of hands as well as material.
One thing I am getting from this is, while those materials are advantageous, for my application, they really wouldn't be necessary. In which case I guess I'm back at square one. That's OK though. If I'm gonna do this I would rather be armed with the knowledge than going in blind.
I once built a bass box for my daughter 1200 * 1500* 600 using a discarded chipboard packing crate. It was 16mm thick and plenty strong and rigid enough with just a little bracing. It lasted about 10 years and after that became a nesting box for the chickens next door and it gave another ten years of service for that before disintegrating. 12mm Baltic Birch might be enough for your needs as might be Sonotube. Adding a flat baffle to Sonotube ??
Nope! Actually a cylinder is what i was going for. The idea was I would use something like MDF as the inner skeleton material. The speakers would be mounted to brackets. Those brackets each have a raised section for the driver. I would cut holes in the outer layer so that the speakers will poke out of the bracket just enough that it becomes a flush mount. Glue the bracket in place and voila. https://www.diyaudio.com/community/threads/project-shakespeare.414757/#post-7728800 if you're interested in looking (just warning you it's a sketch at the moment and not a very good one)
OK Saw that post a short while back
That is easier to do if the drivers sit on a flat baffle.
Use the correct tube size for the driver, set the driver into the tube then insert the driver tube into the upright Sonotube at a 90 degree angle?
That is easier to do if the drivers sit on a flat baffle.
Use the correct tube size for the driver, set the driver into the tube then insert the driver tube into the upright Sonotube at a 90 degree angle?
Nope. The flat part of the baffle would just be the brackets. The rest - opens like a trashcan (so to speak) I think I need to do more than sketches lol
Oh thought you meant 90 degrees on its side my bad. Yeah I figure it would have. Never said it's original. A cylinder is just a better shape than a cuboid. Making it a sphere would be a little TOO challenging lol