Sub box that is light?

Accurate_db

CarAudio.com Newbie
Back in the day there was super light mdf, but people blasted it with spl and was no good for subs. How about today? I heard in automotive unibody construction they use sandwiched foam for strength and rigidity while saving weight. Anyone sandwiched foam with fiberglass? Cause weight is important. Although heavier in car audio means more quality.
 
Back in the day there was super light mdf, but people blasted it with spl and was no good for subs. How about today? I heard in automotive unibody construction they use sandwiched foam for strength and rigidity while saving weight. Anyone sandwiched foam with fiberglass? Cause weight is important. Although heavier in car audio means more quality.
Light and MDF are mutually exclusive.

Been building boxes for the better part of 25+ years, never came across any MDF that was not heavier than all of its contemporaries.

Well, there is that cement board stuff...
 
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The lightest you will get will probably be carbon fiber. I had to use light materials when I put systems in planes. Carbon fiber with "just enough" resin. I don't remember the weight, but it was much lighter than a typical fiberglass box. The biggest thing is, don't go crazy with the resin, but make sure you use enough to make a strong bond.
 
Back in the day there was super light mdf, but people blasted it with spl and was no good for subs. How about today? I heard in automotive unibody construction they use sandwiched foam for strength and rigidity while saving weight. Anyone sandwiched foam with fiberglass? Cause weight is important. Although heavier in car audio means more quality.
Foam and fiberglass are used to maintain rigidity without adding weight. There isn;t a lot of attention given to how well that might resonate or not. The reason dense heavy boxes are better is they typically resist resonating. I've actually used 1/2" MDF with a 120ml Mass layer damping inbetween, didn't seem to do any better than the 1.125" MDF, with the insides lined with the same damping material.
 
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Foam and fiberglass are used to maintain rigidity without adding weight. There isn;t a lot of attention given to how well that might resonate or not. The reason dense heavy boxes are better is they typically resist resonating. I've actually used 1/2" MDF with a 120ml Mass layer damping inbetween, didn't seem to do any better than the 1.125" MDF, with the insides lined with the same damping material.

I performed the same tests. You also want to look at expansion. If your box expands, while the sub is moving, then that will affect your bass. Foam and fiberglass have been used in many things to make items lighter. However, it isn't really strong. Take a surfboard, for example. very light, but I wouldn't recommend standing on it with the center not being supported. However, if you don't mind making the walls 2 inches thick and you're not running a high-powered sub, then foam and fiberglass will work. For the baffle, I would use something solid, like just fiberglass or wood, without the foam.

Overall, go with carbon fiber. It would weigh the same, be much stronger, and much smaller.
 
Sandwiched cones (carbon fiber between a foam core) have become popular with carbon fiber but mostly due cause it’s much cheaper then going solid. For an enclosure you are talking something much larger then a cone, which means it needs to be that more rigid. It can be done with fiberglass or carbon fiber, heck I’m sure even Kevlar but you are talking tons of work and big money cost wise just to save weight.
 
Sandwiched cones (carbon fiber between a foam core) have become popular with carbon fiber but mostly due cause it’s much cheaper then going solid. For an enclosure you are talking something much larger then a cone, which means it needs to be that more rigid. It can be done with fiberglass or carbon fiber, heck I’m sure even Kevlar but you are talking tons of work and big money cost wise just to save weight.
Not big money - H U G E money!
 
C.Fiber and Kevlar is very expensive,especially if mistakes are made. I see some really expensive CNC machines used at parts making facilities for C.fiber hoods, air dams, wings, mirrors ect.
 
C.Fiber and Kevlar is very expensive,especially if mistakes are made. I see some really expensive CNC machines used at parts making facilities for C.fiber hoods, air dams, wings, mirrors ect.

Once in awhile I’ll get that person that money is no object and they will say build me two 15’s that not only slam but look amazing. Instead of using a traditional carbon fiber dust cap, what I’ll do is use solid carbon fiber plate from dragonplate. The stuff is beautiful but it cost $92 plus shipping for a 12”x12” piece lol. Cut it to small that’s $92 plus shipping down the drain 😅. I’ve even went as far as to make spider retaining rings (aka spacers) from this stuff in 1/4” which is about $150 🫣. I can machine them out of 3/8” aluminum (6061 T6) and get them anodized for way less then that 🤣.
 
Once in awhile I’ll get that person that money is no object and they will say build me two 15’s that not only slam but look amazing. Instead of using a traditional carbon fiber dust cap, what I’ll do is use solid carbon fiber plate from dragonplate. The stuff is beautiful but it cost $92 plus shipping for a 12”x12” piece lol. Cut it to small that’s $92 plus shipping down the drain 😅. I’ve even went as far as to make spider retaining rings (aka spacers) from this stuff in 1/4” which is about $150 🫣. I can machine them out of 3/8” aluminum (6061 T6) and get them anodized for way less then that 🤣.
Dammned expensive. Ya. Ive ran across those that $ doesnt bother the buyer and just do it and make it look and sound damnned good.. and I need it by next week..👀👀😩😩:poop:!
season 5 ugh GIF by PBS
 
Thanks. Carbon fiber is kind of risky in a toxic way of working with it, though has great properties. I was just exploring my options for future build. Another thought I had was hydroforming, using hydraulic to form metal enclosure as well as braided kevlar and graphite, like used in tennis rackets. But cost is an animal that can get out of control. Anyway, I'm sure in America mdf is responsibly sourced. But in the international wild west, people cut down trees along the equator to make their boxes. Another option to avoid killing valuable trees is a good thing in my book.
 
Thanks. Carbon fiber is kind of risky in a toxic way of working with it, though has great properties. I was just exploring my options for future build. Another thought I had was hydroforming, using hydraulic to form metal enclosure as well as braided kevlar and graphite, like used in tennis rackets. But cost is an animal that can get out of control. Anyway, I'm sure in America mdf is responsibly sourced. But in the international wild west, people cut down trees along the equator to make their boxes. Another option to avoid killing valuable trees is a good thing in my book.
There is always Plexyglass???
 
Depends on how much power you're running and if we're talking a box with sides a foot long or 4 feet long.

Simply, birch is lighter than mdf. The lightest wooden box will be one with the best internal bracing, as internal bracing tends to make a box much stronger per volume used vs the volume used by adding more wall thickness.

Very large bridge design and aircraft frame design is a good place to see how to brace for light weight and elimination of resonance-based structural weaknesses.
 
Bass and lightweight just don't really go together, unfortunately. The nature of the pressure levels of bass requires weight to keep the structure of the box system working. Resonance is so much more powerful of a force vs the weight on something from gravity. Resonance builds energy into a structure at whatever frequencies the structure resonates to, so it amplifies the amount of energy that can be stored, on top of bass being an omnidirectional force that pushes somewhat on everything, so it's just so much stress on the box. Enough power and a strong enough box, then you can start breaking the vehicle apart, ripped metal and broken glass. You can see resonance in your vehicle panels and structures flexing and what not, especially when peak resonances are hit, and your box tries to do the same thing. If the box itself is flexing a ton, that's cancellation.
 
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