I have been wondering for some time now the weight difference between the 2 and decided to go ahead and run the test last night after being inspired by the "how to drop weight" thread. Here are the results!

Boxes in test


Q-Logic QB-112.3 12-inch Single Bandpass Subwoofer Box loaded with a Lightning Audio 12" 300-Watt Subwoofer, P3.12.4
40lbs even!

VS

CJams (backyard) Fiberglass sub-box loaded with an Alpine SWE-1242 TYPE E 12in 4-ohm Subwoofer
23.6lbs!

I weighed the lightning audio in at 7.4lbs, but the online specs say it's 20lbs shipping. But I didn't weigh the Alpine.

Results: Fiberglass box is 16.6lbs lighter loaded!


Unfortunately my curiosity got the best of me after buying the bathroom scale that calculates body fat

 

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Not really the best comparison since you using a bandpass box vs a sealed box and they aren't even close to the same size. Btw my box weighs about 65 lbs loaded and its a single 10".

 

So are you saying I should add 25lbs to the q-logic box for reference? Or are you saying that your box is 41lbs heavier than my fiberglass box, which in turn would help me prove how much lighter fiberglass is.

And btw- the boxes are very close in size, the pic is 2 dimensional so you can't see the rear of the fiberglass box. It's a good comparison for weight, but not for sound.

 

I'm not saying that fiberglass isn't lighter its just that in a comparison you should use the same style and size box and probably weigh without the speakers too.

 

lol word...

 

A little more info of limited value for this thread:
the 3/4" MDF I used for some stuff was roughly 9.88 g/in^2. So, that would make a 14" x 14" panel (by my crude measurements) approximately 4 1/4 lbs, which doesn't seem to be far off.

Anyway, fiberglass has a higher strength to weight ratio, but I don't know about the density and since resin & mat use vary from person to person you couldn't give one number. But without the same perimeter, wall thickness, and internal volume, a direct comparison it of no real value. But yeah, almost always a glass box will be significantly lighter than an MDF one.