Metal Speaker Enclosures ? A bad idea ?

[johnferrier]

Hi guys and gals,


With steel and aluminum in so many wonderful forms (sheet, angled, U, etc.), I wonder what the reason(s) is that metals are not used for speaker enclosures. Apart from possibly weight and cost, why is that ?

Thanks for any and all inputs.


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[dave_gerecke]

Hello johnferrier, I think the main reason you don't see more speaker cabinets made from metal is due to the necessity of having proper machine tools, and proper documentation and dimensional tolerancing. Especially for DIY stuff. Otherwise, there have been cabinets made from metal over the years. The Realistic Minimus-7 is one that comes to mind. Many others of similar design. I have a pair of cabinets from Japan (forget the maker) that were designed of metal, with a tweeter in the center and a 4" driver on one side and a 4" passive on the other.

Peace,

Dave

P.S. Gotta get a driver setup into those cabinets.

[thunk303]

I think Dave hit the nail on the head. Without the skill and high tolerance tools, metal/alloy is allot of work and expensive.

Having said that, if you design something simple that translates to minimal machining on a CNC rig you can get some panels made by a pro workshop to very high tolerances/standard.

Alloy is probably the way to go, think maybe 4000 series which in a 10mm panel for a small enclosure will be super strong and reasonable cheap(ish).

Again, its best to design, check, redesign, check, take a break then redesign with metal jobs, 0.25mm out and she's just flash looking scrap metal.

Dean

[thunk303]

Check out Magico's Web site for inspiration and another one called "ART loudspeakers" I think.

Dean

[johnferrier]

This is quite interesting. Thanks for the thoughts guys!

The Magico Q5




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[jasonharris]

Can I ask, whats the advantage if any?

I have all the tools to work with metal and make something like the above but why would I? Other than the difficulty and a lot more investment in time what would be the benefit.

I wonder how thick the sides are on the speakers in the picture? Surely steel/aluminium would transmit higher freqs a lot more than timber does.

I really don't know but steel just seems like it would give issues.

[ßart West-VL.]

Metal is a lot stiffer.

[jasonharris]

I just picked up two pieces of aluminium, each 10mm thick. One was about 500mm long x 125 and the other ~400mm long by 250mm. Compared to a similar sized piece of wood the aluminium seemed to resonate worse after hitting it.. Perhaps not scientific but if I didnt know anything else I would use timber based on that test.

[dave_gerecke]

Hello jason, I understand why your observations may deter you, but there's more to it than that. Notice that there is extensive bracing in various directions, this stiffens the baffle and other panels. This stiffening reduces the apparent surface area that can resonate, thus moving the resonant frequency higher. Now that you have the resonant frequency of the cabinet moved high enough, it is out of the range where there is large enough amounts of energy to stimulate resonance in the cabinet.
All materials have a resonance, that's based upon material composition and the size and shape of the material. The trick is to get the resonance out of the region where it's likely to be excited by the energy coming from the drivers. Since bass is the real issue here, get the resonance high enough and it is much easier to control. You can reduce or eliminate higher frequency resonance with other techniques.

Peace,

Dave

[jasonharris]

Thanks Dave, that all makes perfect sense. I work with aluminium a lot but my speaker design knowledge is non existent! I have built some but relied on others to do the plans These sorts of issues a not problems for what I normally use aluminium for.

Thanks,
Jason