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speaker box question

S

supersize75

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gilbert az......by Phoenix
I know this is heavy..and heavy.

But I want to make a sealed sub box and place it here my console was, oh did I mention I want to use 1/4 inch plate.

I am npt looking for a high quality sound, just some base, right now I have to 6x9's under the seats firing tward the firewall. Sound ok considering I don't run a top or doors.

Wondering if this is thick enough to resist wierd sounds and whee I should point the sub/subs. Thinking of a type-R, I had them in the suburban and loved them. /forums/images/graemlins/ears.gif
 
dont think 1/4" will be enough, you might try welded 5/8" plate. yeah, that'd do it.

j
 
You might be better off with 1/8" plate, then re-inforce the long sides with straps of metal welded in vertically (think "I" beam structures) to stiffen those spans of metal...

The sound pressure will try to bulge the box in the center of each long dimension of the box....thick metal is a "brute force" approach to fix it. Thinner metal with bracing (and some dynamat mounted internally) could make for a very NICE enclosure.

BTW -> This is what I'm planning to do for my "rev 2" stereo in the K5.... metal sub enclosures. /forums/images/graemlins/cool.gif
 
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skip dynamat add .5 to .75 polyfill per cubic foot of box ....

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Not really the same thing.

The polyfill can help create more apparent volume in the box, but won't help to dampen the resonances of the metal box itself. You need to add "mass" to the sheetmetal to make it more immune to vibration...... that's what the dynamat will do for you.

BTW -> I'd add the polyfill too! /forums/images/graemlins/thumb.gif
 
what if I add a couple of herculiner coatings to it? that should help also plan to herc the outside so it dosn't look so plain, then paint it or something.

while the herc act as a decent sound deadener /forums/images/graemlins/ears.gif
 
One of those Line-X or Rhinoliner ones might work, but Herculiner seems to be a thinner coating.

Remember, you need to add MASS....heavy items can't be vibrated as easily as lightweight items.

Herculine the outside, Dynamat (actually, use the McMaster polymeric stuff and save $$$$) the inside with a few layers of that goodness.... /forums/images/graemlins/cool.gif
 
yeah, herc has almost no sound deadening qualities to it at all. Hard to imagine that if u took down ur box to the local Line-X place all prepped and ready to go that they would charge you all that much. Herc kit is onsale now for $60... prolly wouldnt be much more for Line-X on somethin that small.

j
 
Maybe so, but you can buy a lot of Polymeric Mastic for $60.......A REALLY LOT.
 
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Why not build it out of MDF, the surround it with the metal?

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At that point, the MDF serves no real purpose. The steel is strong and can be "damped" with the dynamat-type product.



The MDF is going to cost internal volume....it absorbs moisture from the air, it's heavy....etc.

I dunno.....sounds like twice the work for no benefit?? /forums/images/graemlins/eek.gif
 
Just want a beefy box, that is a pain to steel and can be bolted through the floor, I plan to drill and tap treads to the bottom and run the bolts from under the cab /forums/images/graemlins/eek.gif

Yea..its overkill then of coarse I will add a top part with cup holders and a recesed spot for a cb, kind of hard to exsplaine /forums/images/graemlins/tongue.gif

thanks for the info guys, toss and ideas my way that ya got /forums/images/graemlins/ears.gif
 
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Maybe so, but you can buy a lot of Polymeric Mastic for $60.......A REALLY LOT.

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tru dat, but the line-x makes the box rust proof. /forums/images/graemlins/grin.gif

j
 
Greg I always thought you were crazy for wanting to make a box out of steel...It really is just the wrong material. The problem is it has a low specific bending stiffness (bending stiffness has alot to do with how thick something is and a less dense material will be thicker for the same mass and most likely be stiffer). I am considering a lay-up of fiberglass over balsa wood for my sub inclosure (kevlar would be even better!). What is so wrong with wood? My dad (a woodshop teacher) told me I should use baltic birtch plywood...but that doesn't sound easy to shape...
 
Dan,

Well OK.....comparing "like for like" thicknesses of material, metal may be easier to bend.....but I think metal would be worth the trouble for a few reasons:

1. Water resistant - Steel could be painted or Line-X'ed, aluminum would not require anything to protect it...just let it oxidize. Wood by contrast will absorb moisture unless treated (inside and outside of box)

2. Security - A steel box can be welded into the truck. That type of securtity is tough to beat. Also, you can use the existing sidewalls of the truck as the rear of the box to simplify what you need to build. Weld the remaining sections into the bedsides and create what you need. Additionally, once you commit to doing it in metal, you are not constrained to stop the box at the floor of the truck. Why not cut a hole in the floor and let the box grow into that "unutilized" area below the floor section (to give you even more box volume)??

3. Box Volume - While on the subject of volumes, I'm still convinced that by the time to add all the necessary bracing to a steel (or aluminum) box, you will still lose less internal box volume than with a conventional 3/4" MDF type box. The outer dimensions of the box are always the "fixed" constraint, so the material thickness always steals the internal space from you.

4. BLING - This is self-evident and needs no further explanation.... /forums/images/graemlins/grin.gif
 
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4. BLING


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I'll take two.

Seriously though, it sounds like a pretty awesome idea to actually weld and build that box into the truck. This may be a dumb question, but I was just curious, even once it's padded and has mass, wouldn't a steel speak box sound different than MDF all other things being equal? /forums/images/graemlins/confused.gif
 
My take on it, is that the box will "sound" like whatever it's allowed to sound like based on the damping materials used inside.

True, wood will have a different sound from metal. Knock on a piece of wood, and a piece of metal with your eyes closed...you will KNOW which one is which by the sound they make. Cover them with Dynamat, and carpet underlayment (aka juking, which I have also used INSIDE sub enclosures) and knock on each one again. I'd argue that all that extra material has effectively "masked" the sonic properties of the underlying material quite nicely!

Remember also, mounting a speaker in a metal enclosure isn't exactly a "wild" idea.... most likely you've already got a set in your truck doors at this very moment..... /forums/images/graemlins/wink.gif
 
Is that what those big holes in my doors were!? /forums/images/graemlins/shocked.gif /forums/images/graemlins/rotfl.gif

Yeah, no speakers in my truck at the moment. Well...maybe one of those mono center of the dash speakers or something. So I'm just sort of scoping out ideas at the moment. And your NorCal gallery certain is a great source for those.

Hope you haven't gotten tired of hearing, "Cool setup Greg!" /forums/images/graemlins/thumb.gif
 
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Well...maybe one of those mono center of the dash speakers or something.

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I've got a plug wired to that speaker on my '75 so that I can use it as the "external" speaker for my CB. It's much easier to hear than the bottom-firing speaker that's built into the CB. /forums/images/graemlins/thumb.gif
 
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