For me this is much cheaper, much quicker, much easier than MDF. But is it better?
Im thinking a welded 30mm by 30mm by 2mm thick square tubing for the frame lined with 1mm sheet metal panels on the inside and out and the cavity and all tubing filled with sand. Front panel 25mm MDF.
How do you think this compares sound wise to a standard build 25mm MDF box for a floor stander like this?
Im thinking a welded 30mm by 30mm by 2mm thick square tubing for the frame lined with 1mm sheet metal panels on the inside and out and the cavity and all tubing filled with sand. Front panel 25mm MDF.
How do you think this compares sound wise to a standard build 25mm MDF box for a floor stander like this?
Attachments
It certainly seems like solid construction, I don't see any disadvantages of your method, except for the weight and complexity to build (for me, if you say it's easier for you then all the better!)
You'll probably still want to put some fairly dense stuffing in the lower portion of the enclosure to help damp standing modes due to the geometry.
-David
You'll probably still want to put some fairly dense stuffing in the lower portion of the enclosure to help damp standing modes due to the geometry.
-David
I can see a small problem if the diagonal bracing is the same profile as the uprights; how is the sand going to flow thru to fill all of the voids?
I can't weld for nuts so I would be intimidated by the proposal.
Are the diagonals actually needed in a welded construction? and are you going to use rustproofing before adding the sand as corrosion may be a long term problem.
I can imagine these in brushed stainless steel how-ever SEXY!
I can't weld for nuts so I would be intimidated by the proposal.
Are the diagonals actually needed in a welded construction? and are you going to use rustproofing before adding the sand as corrosion may be a long term problem.
I can imagine these in brushed stainless steel how-ever SEXY!
Panomaniac,
Wouldnt internal reflection be the same in a timber construction of the same dimensions?
Moondog55,
I didn't draw it but the tubing and particularly the bracing will have 10mm holes drilled here and there for the sand. Definitely rustproof and I will ensure the sand is ultra dry. Stainless WILL be tempting...
Will this concept be ok for a sub enclosure?
Wouldnt internal reflection be the same in a timber construction of the same dimensions?
Moondog55,
I didn't draw it but the tubing and particularly the bracing will have 10mm holes drilled here and there for the sand. Definitely rustproof and I will ensure the sand is ultra dry. Stainless WILL be tempting...
Will this concept be ok for a sub enclosure?
Well, yeah - the wavelengths should be the same. It's just that metal is so much more reflective than wood.
I'm sure there is some wise-guy here who will say "oh no it's not" and spout proofs. But I've been inside metal boats and wooden boats - I know which one reflects more sound!
But it should be easy enough to kill those reflections, just have to be sure to do it!
I'm sure there is some wise-guy here who will say "oh no it's not" and spout proofs. But I've been inside metal boats and wooden boats - I know which one reflects more sound!
But it should be easy enough to kill those reflections, just have to be sure to do it!
Stiffness
I have been thinking about this stiffness issue and just how stiff a sand filled panel enclosure needs to be....
Someone PLEASE correct me if Im wrong here,
For a loudspeaker enclosure we require stiffness for only 2 reasons that I can think of. One, so the enclosure doesn't expand and contract with the pressure changes from the woofer and two, to raise the sympathetic panel resonance frequencies so they are less audible.
Even if I completely remove the steel tubes from my enclosure above and simply used two 1mm sheet metal walls and fill the cavity with sand it would still out perform a well braced timber enclosure. Is this so?
I don't intend to actually do this as it's easier to include the frame, it's simply the notion of a truly dead panel not requiring stiffness Im questioning.
I have been thinking about this stiffness issue and just how stiff a sand filled panel enclosure needs to be....
Someone PLEASE correct me if Im wrong here,
For a loudspeaker enclosure we require stiffness for only 2 reasons that I can think of. One, so the enclosure doesn't expand and contract with the pressure changes from the woofer and two, to raise the sympathetic panel resonance frequencies so they are less audible.
Even if I completely remove the steel tubes from my enclosure above and simply used two 1mm sheet metal walls and fill the cavity with sand it would still out perform a well braced timber enclosure. Is this so?
I don't intend to actually do this as it's easier to include the frame, it's simply the notion of a truly dead panel not requiring stiffness Im questioning.
So why not building a geoidal structure composed of many polyedres ?
C'mon ! The force of the pressure of a moving membrane can be easily handled by the normal materials usually found in loudspeakers . Eventually the entire surface could be covered by thick steel ...or put in an electro galvanycal bath to get that silver finish.
Just joking
C'mon ! The force of the pressure of a moving membrane can be easily handled by the normal materials usually found in loudspeakers . Eventually the entire surface could be covered by thick steel ...or put in an electro galvanycal bath to get that silver finish.
Just joking
Diagonal braces aren't needed, the steel sheet will provide more than enough shear bracing. The sheets might bow outwards slightly under the pressure of the sand, so you may need cross braces attached to the sheets to prevent this.
I'd be more concerned with the cosmetics. Unless you're deliberately trying for a steampunk look, they won't look pretty. You could consider having stainless steel cosmetic covers bent up to slip neatly over the cabinets, similar to the covers available for covering ducting for extractor fans in kitchens. They are also available ready-made in a variety of sizes and lengths, if your cabinet dimensions are compatible. They have a lip on the open edges ideal for neatly fitting between the cabinet body and the baffle. Just add a neat wooden top cap for Spousal Acceptance Factor.
Since many of the ready-made duct covers have a "U" profile, you could roll some steel sheets to make a half-round profile back for your cabinet to match the cover. Even higher SAF.
I'd be more concerned with the cosmetics. Unless you're deliberately trying for a steampunk look, they won't look pretty. You could consider having stainless steel cosmetic covers bent up to slip neatly over the cabinets, similar to the covers available for covering ducting for extractor fans in kitchens. They are also available ready-made in a variety of sizes and lengths, if your cabinet dimensions are compatible. They have a lip on the open edges ideal for neatly fitting between the cabinet body and the baffle. Just add a neat wooden top cap for Spousal Acceptance Factor.
Since many of the ready-made duct covers have a "U" profile, you could roll some steel sheets to make a half-round profile back for your cabinet to match the cover. Even higher SAF.
Ahhhh ...hA! Now I understand why the tall and narrow boxes are becoming so popular !
www.eddies.it/bio/grafica/image002.jpg
www.eddies.it/bio/grafica/image002.jpg
... and since you're using 1 mm steel sheet, you aren't constrained to a flat sided cabinet. You could roll the sheets into an ovoid profile, with round or square section tube verticals at intervals to maintain the inner and outer wall spacings. If you fasten (weld / rivet) the spacers to the inner wall and make the outer wall a snug fit over them, you wouldn't need to fasten the outer wall to the spacers (no welds or rivets to hide). The outer wall could then be stainless steel for a ready-made finish.
Rigid, stiff, dead... whatever the cabinet structure is, there is an inevitably weak link in the whole thing -- driver's diaphragm.
The pressure change, internal reflections, or standing waves... etc inside the box would escape through the weak point -- in this case, the driver. (And, outside the box, there'd be room acoustic issues which play an even bigger part of the game.... )
I know it'll probably bring up some arguments, but this is my own first hand experience.
I have built some big, heavy, dead boxes with heavily braced and damped internal structures, they still boomed like hell with little to no vibrations on the box panels. So it's obvious not the boxes, but other things I did wrong....
Sorry for spoiling the pleasure, but I really don't think it's just so important to build an invincible box. Good enough is good enough. There are many other things to worry about before or besides this.
A creative and original building technique is excellent, though.
If I can handle metals, I'd probably build some space frame with transparent skin or just leave it OB -- I mean, metal skeleton alone is spectacular enough! Why cover it?
The pressure change, internal reflections, or standing waves... etc inside the box would escape through the weak point -- in this case, the driver. (And, outside the box, there'd be room acoustic issues which play an even bigger part of the game.... )
I know it'll probably bring up some arguments, but this is my own first hand experience.
I have built some big, heavy, dead boxes with heavily braced and damped internal structures, they still boomed like hell with little to no vibrations on the box panels. So it's obvious not the boxes, but other things I did wrong....
Sorry for spoiling the pleasure, but I really don't think it's just so important to build an invincible box. Good enough is good enough. There are many other things to worry about before or besides this.
A creative and original building technique is excellent, though.
If I can handle metals, I'd probably build some space frame with transparent skin or just leave it OB -- I mean, metal skeleton alone is spectacular enough! Why cover it?
Don,
great idea's mate, and easy too. I'll be giving that some thought. Ovoid provides the strength to hold it's self. No uprights required just spacers. Nice.
I wonder how expanding foam would go instead of sand......
CLS,
I've arrived at these methods because Im trying to avoid using timber for several reasons. If my method turns out to be an 'invincible box' it's something of a bonus, not a requirement. You already have the invincible box ...but OB has it's own set off issues that Im not prepared to deal with and pay for.
great idea's mate, and easy too. I'll be giving that some thought. Ovoid provides the strength to hold it's self. No uprights required just spacers. Nice.
I wonder how expanding foam would go instead of sand......
CLS,
I've arrived at these methods because Im trying to avoid using timber for several reasons. If my method turns out to be an 'invincible box' it's something of a bonus, not a requirement. You already have the invincible box
...but OB has it's own set off issues that Im not prepared to deal with and pay for.- Status
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