Materials

Madmike2

Member
2005-04-24 11:55 pm
Toronto
Hi guys

Just came from a plastics factory where i was investigating material.

they have some cool stuff phenolics and the like some of it apparently i cannot build with because it does not glue together. It needs to be welded. Since i cannot afford Peter Daniels amps at 1200 bucks each at the moment i am going to continue improving my speakers. What is a better choice for use for an enclosure ? 1.5 inch Lexan ? 1.25 inch Plexi 1.25 inch HDFP ?

All of these i can screw and epoxy. the other stuff they have needs special welding equipment for it and is 1200 to 3000 dollars a sheet for 1 inch!!
 

Madmike2

Member
2005-04-24 11:55 pm
Toronto
ABS has a very high hollow ring when you knock on it and is generally not very thick if i got my plastics correct. The stuff i was admiring is very dense and 'dead' you hit it and its a dull thud. Less of a response on the knock test then 1 + inch MDF thats for sure. I cant afford the stuff they made the Wilsons out of. They carry it but it is close to 6000 dollars for a 4 x 8 sheet of 1.75 inch and needs special construction techniques.

I am really looking at the opaque Lexan 37mm stuff. Cut and all i can get 2 enclosures worth for 600 dollars. I cant get much deader cabinet material then that:) It s gonna weigh a ton though:(
 
Mike,

Your talking about a sub. If you want a see-thru sub, by all means go for it. Otherwise you are just wasting your money. The resonant frequency of just about any material you use in the panel size of a typical sub just isn't going to come into play. If you want overkill that is effective, do it with bracing. Then use a 2 layer approach if you want extra overkill. It doesn't matter how dead you think that plastic is, it still needs bracing. It might be great for speakers though, but for a sub it's a waste unless you want the see-thru look.

My advise is to use something easy to work with like plywood and go crazy with the bracing. Put the $500 in your pocket or spend it on something usefull like bass traps.
 

Madmike2

Member
2005-04-24 11:55 pm
Toronto
hmmmm y'all think it s a waste ? And it is for the subs AND the top end. I wanted to re build my 2 ways with this stuff. Same enclosure dimensions just not Russian birch. Also, I figured that using this material with bracing would remove the enclosure flex and energy transfer elements as close to completely as possible.

Corian is way stupid pricing. I am not rich :D

From your experiences, do you think 1 inch MDF or layered birch over braced will be enough to adequately keep the bass coming from the driver and not the cabinet ?:confused:
 
BassAwdyO said:
You could make your enclosures from MDF concrete and lead and end up with something heavier and probably deader

But it won't sound ANY different than a well braced sub made out of MDF or good plywood, so why waste the time ? Mains MAY be worth some extra effort in this area because they are playing a very wide range of frequencies.

I believe the amount of effort put into the area of cabinet walls by many DIYers is complete nonsense. Why go to all that trouble to:

1. Make a box with parallel sides.

2. Invest so much time and expense to create a "dead" box
that has this huge driver hole in it. The only thing separating
the inside of the box from the outside world is the driver cone.
This is made of a just a thin layer of paper or other lightweight
material that if you just scratch or tap lightly on, makes a very
audible sound.

Do people really believe all these forces that they are so concerned about with regard to every other surface on the interior of the box magically don't affect the cone, a thin lightweight surface mounted on a magnetic spring?

If you want a sufficiently dead box, build a well braced box. If you want an extra dead box that can't support a standing wave, make it a truncated pyramid with no parallel surfaces. The alternative is to follow the overkill experts and jump right off the bridge with them.
 
I dont like 'boxes' so i always build slanted or 5 sided. Also in sub frequencies i dont think ill be building anything long enough to nessecitate worring about standing waves regardless as those wave lengths are much to large. My top 2 ways are 5 sided enclosures.

I get the point though. I dont 'need' exotic material, i just need to build better braced enclosures. I have a bad habit of spending what i got when i got it. I thought it would be cool to build my own 'X' material enclosure :) i guess i will stick with the 'B' material for now.

As a side note John, they do it so no acoustical energy is emitted from anything BUT the little paper or thin materialed transducers in them , where it is supposed to come out of. Well as near to 100% as possible. Listen to an NHT floor stander next to an Energy c5 in the same room and tell me there isnt a difference in the way they image. The NHT is a dense cabinet and has great sound, much better then the Energy in my HUMBLE opinion and i would attribute that to the box that energy builds thumping away to the music along with the drivers inside them. Put a drink on top of the NHT and it wont even ripple.
 
the weight of the enclosure(especially sub) has a large effect. When a subwoofer with a moving mass of say 350 grams is pumping away 3 inches peak to peak excursion(which is basically what a tumult can do) at a frequency higher than 20hz there is a pretty good deal of mechanical inertial force on the enclosure. A light enclosure no matter how stiff it is will vibrate due to this. The only way to prevent it is either a heavy enclosure, or push push opposing driver mounting.