Speaker Boxes Made out of Metal

[John Biles]

Hello Everyone,
Me Again will another idea?
Has anyone one the forum experimented with welding up a speaker box out of say 6mm think steel and welding in cross braces to prevent wall flex.
I am sure you could get a very stiff box with this idea?
One thing i hate about my normal boxes is the boxy sound you get at times.
I know it would be heavy, but if it worked it would most likely be worth it.

[Stocker]

It could sound tinny.

To get the obvious joke out of the way.

If you have the materials on hand, go for it. Otherwise, use adequately spec'd MDF, HDF or plywood. Stay away from chipboard and LDF. Other exotic materials use as required

Anything done right will not resonate in a frequency of concern for the drivers installed.

Metal has one big advantage: you finish it, it's done moving. No swelling with weather (even soaking in water), no shifting joints.

[Variac]

Somewhere in here I remember a guy who tried steel about that thickness. He said it rang. I would think something like pickup bed liner sprayed on the inside would help. Or glue something like vinyl floor tile onto the inside. There is special stuff sold for this purpose too.
The HIGHLY regarded Wilson Benesh speakers use a metal framework of some sort.

[SY]

Don't forget the aluminum cabinet on the old Celestions...

[Dane]

Krell's LAT-1 is made from Extruded Aluminum

Krell LAT-1

[Audiophilenoob]

alum seems like the preferable material over steel...

it's roughly the same strength but is far lighter

[Variac]

You gotta define strength- the same problem as defining conductivity.
"tensile strength per pound?" Steel wins I'll bet. Its hella strong.

I think Alu's lower weight allows thicker walls which make it "stiffer per pound"

I think alu is inherently better damped (for a metal!) Not too many church bells made from aluminium...

It does seem that Aluminum is more successful. Now steel/sompthin' constrained composite might be pretty good! (I think thatthe Benesh folks combine a steel framework with carbon sandwich panels..tasty!

[Audiophilenoob]

Originally posted by Variac
You gotta define strength- the same problem as defining conductivity.
"tensile strength per pound?" Steel wins I'll bet. Its hella strong.

I think Alu's lower weight allows thicker walls which make it "stiffer per pound"

I think alu is inherently better damped (for a metal!) Not too many church bells made from aluminium...

It does seem that Aluminum is more successful. Now steel/sompthin' constrained composite might be pretty good! (I think thatthe Benesh folks combine a steel framework with carbon sandwich panels..tasty!

alum is softer than steel no doubt and therefore has higher dampening properties... but 6mm steel is VERY strong... it would take a lot of pressure to flex that...

1/4" alum would be nearly impossible to bend... but resonance is still a problem

as far as that though you're right steel per thickness is stronger than alum

[Artmaster]

gday!
let's compire material's properties:

Material E, 109*Pa
aluminium 70,0-71,0
beton 14,6-23,2
tungsten 415
granit 49
iron 190,0-210,0
kapron 1,4-2,0
brick 2,7-3,0
ice(about t=-4oC) 10
marble 56,0-73,0
plexiglass 2,9-4,1
spider's web 3
rubber 0,9
lead 16,0-17,0
steel 200,0-220,0
glass 50,0-60,0
cotton 12
grey iron 115,0-160,0
silk 13
wool 6
ebonite 3

do not tell fortunes for it.

[Scottmoose]

Unfortunately, because something is stiff, it doesn't necessarily follow that it will be uncoloured, or not resonate. Quite the reverse. Think of tuning forks.

The best anaolgies I can think of, and they have relevance here, are in swords, and battleship armour-plate. Tap a bronze sword, and you'll get a relatively dull 'thud'. A steel one will vibrate and ring quite cheerfully. That's why they tended to combine several metals for these things -to prevent them shattering. Same with armour-plate. Steel, when it was introduced, was harder than the older iron armour, but it shattered easily. So for a number of years they used compound armour -a nice hard steel face supported by a tough iron backing.

All of which sounds as if it's a bit of a downer, but it's not impossible, and superb results can come. Look at how good some metal drivers are, though it's taken quite a while to get them to a really good standard (thank you Acoustic Energy and others). So there's no reason metallic cabinets have to be poor. I still have a pair of the aforementioned Celestion SL600s in the loft (2 blown tweeters). They used a propriatory aerolam technique, mostly swiped from the aircraft industry using aluminium, which is a better bet than steel for this sort of thing. I don't think they can rebuild these cabinets any more though: I believe their supplier went out of business, though I speak under correction here. Unless of course, you can fashon a cab. out of bronze of course... A cabinet constructed from two different types of metal might also be worth trying. Good luck. There are real possibilities from metal cabinets, just like drivers, but it'll need some heavy thinking.