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Old 4th August 2004, 01:44 PM   #1
VvvvvV is offline VvvvvV  United Kingdom
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Default Ultimate DIY cabinet materials?

What would be the ultimate cabinet materials?

For example if you could mould yourself a cube of some state-of-the-art tons per square inch concrete, would it be worth it?
If you pick up some pvc barrels from a building site, would it sound good? if you mould yourself a round concrete ball and stuck 2 didgeridoos out of the top? Would that be the best thing?

anyone come across some good article comparing speaker cabinets musical instruments or about theories of fluid dynamics across cabinet materials ? it sounds really confusing.
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Old 4th August 2004, 03:00 PM   #2
MartinQ is offline MartinQ  Canada
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High-mass uniform building materials are ,by themselves, no longer the choice material in todays high-tech speaker designs. ie, concrete/cement, hardwood, chipboard, fibreboard, polymers, metals, etc.

A speaker 'box' is designed to contain and dissipate the rear-wave energy, the drivers chassis vibration, and provide a stable mount for the driver. A highly rigid and heavy material will do most of this, but is very inefficient at dissipating energy. For this you need some sort of damper, and constrained layer building techniques can give you this.

Also, just as in a cars suspension, the damper has to work harder if the mass to be dampened is high. For this reason, it's best to keep the speaker structure as light (and rigid) as possible, and let the damper dissipate the vibrational energy.

Some searching for 'constrained layer' will bring up lots of information, but some materials could be.

Thin high-grade plywood (baltic birtch, marine, aircraft, furniture), 1/8 or 1/4" masonite or fibreboard, aluminum, steel. These materials are only for structure.

For damping you need some viscoelastic material. Such as:

3M™ Vibration/Sound Damping Products
http://products3.3m.com/catalog/us/e...er/output_html

Dynamat
http://www.dynamat.com/spec_pages.htm (good/quick information about damping)

WSU (Waterproof Shingle Underlayment) = "self-adhesive ice and water barrier" = Roofing Material

-such as-

Peel & Seal
http://www.mfmbp.com/peelseal/index.htm

Grace Ice & Water Shield
http://www.na.graceconstruction.com/...=a&id=74&did=8

WEATHERMASTER™ DG ICE & WATER PROTECTION
http://www.atlasroofing.com/residential/sm_dg.asp

etc, etc, etc... see your local roofing supplier.
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Old 4th August 2004, 03:01 PM   #3
markp is offline markp  United States
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If you could mold 'Corian' or some similar material as some have done it works better than concrete. It is very dead, do not crack, is not porous, machines well, and even looks good(any color you like) but it is very heavy, extremely expensive, and hard to get a hold of the raw material to cast yourself.
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Old 4th August 2004, 06:46 PM   #4
gary f is offline gary f  Canada
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There is something that Martin Q said that is not realy clear for me about mass.

You say that the cabinet need to be rigid and light. But it seems like i would rather have a infinitely heavy cabinet than an infinitely light one. Because a light cabinet cannot keep the frame of the woofer in place as well as a heavy one.

It seems to me that a good cabinet should be massive, rigid and well damped. What do you think

F
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Old 4th August 2004, 07:12 PM   #5
MartinQ is offline MartinQ  Canada
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Gary F: Mass is better 'spent' for damping than just for the sake of mass. The structure should be light and rigid to make the best use of the damping. As a system, it can still be quite heavy, but more effective than mass alone.

A effective system can be intelligently built/designed to produce less noise than a strictly massive one. Yes, infinte mass would produce good results ... and a black hole.

Most drivers have enough mass in the motor/basket assembly as it is, and this can easily be backed up with putty, loaded paint, constrained layers, etc. if needed. But, if the driver chassis is rigidly fixed to the speaker box structure, then you also get an effective transmission of those vibrations to the structure where they will most likely be amplified.

Nip it at the source and minimize transmission. The enclosure has to deal with the rear wave as it is.
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Old 4th August 2004, 08:18 PM   #6
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Marble with black hole 5 and polyfill stuffing inside.
Sealed of course!
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Old 4th August 2004, 08:21 PM   #7
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This pops up every so often. You clicked the "Have you Searched?" option, correct?

http://diyaudio.com/forums/search.ph...der=descending
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Old 4th August 2004, 08:25 PM   #8
markp is offline markp  United States
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You might also consider something with aerolam(a la Celestion Sl6000) and some sort of damping goo on the inside.
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Old 4th August 2004, 09:06 PM   #9
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Does anybody know if there are effective adhesives for wood that have beneficial damping properties, and if their use could be recommended? I've been attracted to the translam method of cabinet construction for various reasons, and the need for many layers of adhesive might present an opportunity to incorporate damping into the structure itself. Or perhaps laminating wood with a damping adhesive would be of little value compared to the more common practive of simply lining or spraying the inside of the box. Any thoughts?
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Old 4th August 2004, 09:37 PM   #10
NH7RO is offline NH7RO  United States
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Default Panel adhesive

Heat Miser, I would suggest Liquid Nails mixed with sand (although I haven't actually tried this yet)--Jeff in Hawaii
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