This raises an obvious, related question.
Obviously 3/4 BB is the go-to choice for most enclosures, with some guys using a second 1/2 piece glued on for the face, and some using MDF for that extra piece.
- But I'm reading that a number of guys here have used 5/8" BB when weight is an issue.
So what is the determining factor here? Surely even 1/2" BB would be strong enough in terms of durability, so are we just talking vibration? If so, couldn't thinner ply work with extra (carefully worked out) bracing? Maybe even aluminum channel, strategically placed?
Surely, things like this have been tried in the past, by SOMEBODY, no? Were they all just failed experiments, and so I'm not reading about them?
Obviously 3/4 BB is the go-to choice for most enclosures, with some guys using a second 1/2 piece glued on for the face, and some using MDF for that extra piece.
- But I'm reading that a number of guys here have used 5/8" BB when weight is an issue.
So what is the determining factor here? Surely even 1/2" BB would be strong enough in terms of durability, so are we just talking vibration? If so, couldn't thinner ply work with extra (carefully worked out) bracing? Maybe even aluminum channel, strategically placed?
Surely, things like this have been tried in the past, by SOMEBODY, no? Were they all just failed experiments, and so I'm not reading about them?
Well, ok, sure. My point is, has anybody done experiments, to find the perfect compromise? I would certainly think so.
Same goes for drilling all those holes in the internal bracing. At some point, is it too much?
I have to think that touring companies worry about every pound, no?
CableAddict...the link you shared to QSC, the Q in that brand stands for the founder Pat Quilter...now Pat sold his interest in that firm years ago to pursue what he really loves and that’s building world class. fly-weight, Class D electric guitar amps. If you go to this link:
Quilter Performance Amplification
and reach out to him with your question, there’s a very good chance he’ll respond to you. He’s very intelligent, knowledgeable and helpful.
Quilter Performance Amplification
and reach out to him with your question, there’s a very good chance he’ll respond to you. He’s very intelligent, knowledgeable and helpful.
I've just dabbled - I experimented with individual 'beams' and a prototype horn, but haven't made a sub or anything beyond a prototype with this method. Because fridges, surfboards and other rigid objects are built on a foam core, I can't see why it wouldn't work for a sub.
This chap has done a lot of (non audio) builds with foam, and has lots of ideas you might want to borrow.
Sawfish, an Unsinkable, Lightweight, Foam Kayak (23 Lbs). Free DIY Kayak Plans, the Hardware Store Boat: 32 Steps (with Pictures)
Seafoam Kayak, the Unsinkable Foam Kayak Anyone Can Build, 16 Pounds and Eight Feet of Fun: 16 Steps (with Pictures)
He gets a lot of strength from humble materials. e.g. in the middle of the 'Seafoam' article, he describes reinforcing cockpit of the kayak with cardboard that's been soaked with "1/3 mineral spirits mixed with 2/3 oil based polyurethane floor sealer".
A construction site floor protector (e.g. Ram Board) might be a good material for this.
Depends on whether it needs to be waterproof. Lots of good info in the links.
The panels themselves are very thick, you'd have to adjust the plan for that (i.e. make the speakers about 8cm bigger).
Thickness = rigidity, so thickness is a good thing.
good article - sounds like the green foam insulation board sold by Lowes in the US is tougher than the pink Corning stuff. What are teh best-simple ways to cut it really straight and square? Can it be cut with a circular or table with a certain blade? (I tired cutting the pink stuff on a table saw with a fine tooth blade - it overheated the plastic, bonded to blade with a fast kickback destroying the test piece
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I've cut the pink stuff before with a track saw, using a good carbide melamine type blade at medium speed.
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I've been using Owens-Corning Formular insulation board, from Home depot, as interior filling on trap boxes made deliberately too deep, to be able to tune volume by adding slices.
It's purple
It cuts easy on a table saw with any blade suitable for fine cutting plywood.
I can also get very clean 45 degree cuts using a track saw....I love track saws !
Or even 9mm, the Bill Fitzmaurice folded subs are inherently so well braced that cabinet vibration is a non issue, he recommends 12mm Aurauco ply, which is 2/3 the weight of BB, and almost as ding resistant.
https://billfitzmaurice.info/index.html
thanks - it was probably the ~120 tooth cheap blade being dull
Art's "Keystone" might (?) be tougher to make out of 12mm than the BFM tuba type. Then again, maybe not if the bracing is thought out
https://lh6.googleusercontent.com/-...AAAAGp0/t1T-ZUSUDTU/w527-h685-no/Keystone.jpg
(I'm thinking foamboard for an outdoor Karlson)
Art's "Keystone" might (?) be tougher to make out of 12mm than the BFM tuba type. Then again, maybe not if the bracing is thought out
https://lh6.googleusercontent.com/-...AAAAGp0/t1T-ZUSUDTU/w527-h685-no/Keystone.jpg
(I'm thinking foamboard for an outdoor Karlson)
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Here's a different approach that might work. What do you guys think? :
Supposed you used 3/4" BB or similar, then cut relief holes in the ENTIRE cabinet, such as Horst shows in his braces. THEN, wrap / epoxy fiberglass around the entire outside?
You'd still have strength, the fiberglass would likely have a low resonant frequency, and heck, you even gain some "free" internal volume.
Does this make sense, or am I overlooking something?
Supposed you used 3/4" BB or similar, then cut relief holes in the ENTIRE cabinet, such as Horst shows in his braces. THEN, wrap / epoxy fiberglass around the entire outside?
You'd still have strength, the fiberglass would likely have a low resonant frequency, and heck, you even gain some "free" internal volume.
Does this make sense, or am I overlooking something?
I'm already insane, so no problem there.
I'm also thinking, instead of fiberglass, maybe several layers of carbon-graphite cloth, if it's available in small quantities. That would also mean no need to paint them, and they'd be extremely scratch / mark resistant.
If this were to work, I could probably manage to move around a pair of of Art's slim keystone subs.
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All kinds of clever composite layups could be considered for this application, but don't forget the worst kind of forces put on gigging speakers is getting to/from the venue. Crush resistance of a thick foam with a highly loaded skin is definitely winning in stiffness to weight, but is quite fragile.
Design for the demands of the application, which for a sub should be a strong baffle and hefty internal bracing.
Design for the demands of the application, which for a sub should be a strong baffle and hefty internal bracing.
Used to use a thin layer of black colored fiberglass over speaker cabinets to make them more rugged. The fiberglass "dust" from transportation abrasion would cause anyone handling the cabinets to itch, so required painting.I'm already insane, so no problem there.
I'm also thinking, instead of fiberglass, maybe several layers of carbon-graphite cloth, if it's available in small quantities. That would also mean no need to paint them, and they'd be extremely scratch / mark resistant.
If this were to work, I could probably manage to move around a pair of of Art's slim keystone subs.
From what I read, carbon fiber dust is even worse than fiberglass dust.
Both are a nightmare to work with compared to plywood construction.
Fiberglass is around 3 times heavier than Aspen plywood, specific gravity of 1.6 compared to .51.
Using triangulated bracing and thinner plywood would save almost as much weight as could be possible with any composite material, with less work, expense, and mess.
That said, increasing the build time by around 4 times for a shell weight savings of 40% still does not appeal to me.
Wow. Great info. Still, there must be SOMETHING out there that would work & be "safer." Or maybe just carbon fiber covered in Duratex, or even a 2-part epoxy paint. (Like bedliner paint)
It sure appeals to me.
(And my back.)- Status
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