I'm sitting down to design a small box for an LS3.5A combination 2 way bookshelf. I can see how to quickly make a box glued together on all sides with only the front open. If the front was aluminium it would screw straight onto the thick sides+top+bottom (40mm). Such a removable front would make it easy to change speaker configurations. I haven't seen anybody do this - is there any reason why not? What are the considerations for a front panel - rigidity, lack of resonance..... Surely a 4mm or 5mm aluminium plate would have those qualities? Should mate well to the driver chassis too, and even look cool. Does this sound OK to you DIY people? Any examples of this? Andy
Check Intertechnik>>
I don't speak much German, and when I went through their site looking at the pictures I couldn't find anything - where is it on their site? I was going to make the panels and I wondered how exactly to cut out a large round hole - bigger than all my hole saws. I suppose a jig saw. Mine says up to 8mm aluminium. Any other ideas?
I don't speak much German, and when I went through their site looking at the pictures I couldn't find anything - where is it on their site? I was going to make the panels and I wondered how exactly to cut out a large round hole - bigger than all my hole saws. I suppose a jig saw. Mine says up to 8mm aluminium. Any other ideas?
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laminating something on the inside isn't going to deal with the high acoustically reflective surface on the outside? the first reflections would come off the baffle...
OTOH there are some speakers that use felt on their baffles.
to me these two opposites can be likened to the way speakers don't sound so good in a tiled kitchen compared to a carpetted lounge.
OTOH there are some speakers that use felt on their baffles.
to me these two opposites can be likened to the way speakers don't sound so good in a tiled kitchen compared to a carpetted lounge.
tktran said:
I never suggested that it would. The laminate on the inside was to dampen vibrations in the panel (ringing). Plenty of baffles are made from hard acoustically reflective surfaces. Dealing with the edge shape and applying wool felt to the outer baffle surface are some ways to deal with the effects you mention.
Plenty of baffles are made from hard acoustically reflective surfaces>>
Some sides of the box would be made from solid mahogony, 32mm thick. Is this also "hard acoustically reflective" - i.e. a bad thing? I see cabinets made in all kinds of natural woods. On the other hand, I read in the BBC instructions for their speakers (LS3.5A e.g.) that they used birch because they found that hardwood sounded worse with the mid-bass unit. This discussion could include the question "what are the desirable properties of panels for building speaker boxes" - this includes aluminium, hardwoods etc etc. What about steel? Is this bad because it rings or because it's magnetic?
Some sides of the box would be made from solid mahogony, 32mm thick. Is this also "hard acoustically reflective" - i.e. a bad thing? I see cabinets made in all kinds of natural woods. On the other hand, I read in the BBC instructions for their speakers (LS3.5A e.g.) that they used birch because they found that hardwood sounded worse with the mid-bass unit. This discussion could include the question "what are the desirable properties of panels for building speaker boxes" - this includes aluminium, hardwoods etc etc. What about steel? Is this bad because it rings or because it's magnetic?
laminating something on the inside isn't going to deal with the high acoustically reflective surface on the outside>>
How about a sandwich? Two alu sheets with something like bitumen in between? I remember the designer of Totem speakers saying that dampening between two surfaces was much more effective than dampening on one surface alone.
How about a sandwich? Two alu sheets with something like bitumen in between? I remember the designer of Totem speakers saying that dampening between two surfaces was much more effective than dampening on one surface alone.
andyjevans: tktran's posts make no sense to me. he seems to be intermixing principles of speaker building and small room acoustics and coming up with some "unique" theories of his own.
a 3/4" x 12" x 30" aluminum baffle looks like it would cost about $125- $150 usd each before machining. compare that to about $5 for mdf. there may be other issue regarding why aluminum is not the best baffle material, but i suspect there is not a lot of experience in the diy community because of its relatively high cost and the need to have it professionally machined (for most people). i have a pair of jbl lsr 25p's and their entire enclosure including baffle is aluminum. i think genelec is the same way. the infinity prelude mts has an extruded aluminum enclosure, but i am not sure what the baffle itself is made of. doesn't dynaudio's flagship speaker have an aluminum baffle?
a 3/4" x 12" x 30" aluminum baffle looks like it would cost about $125- $150 usd each before machining. compare that to about $5 for mdf. there may be other issue regarding why aluminum is not the best baffle material, but i suspect there is not a lot of experience in the diy community because of its relatively high cost and the need to have it professionally machined (for most people). i have a pair of jbl lsr 25p's and their entire enclosure including baffle is aluminum. i think genelec is the same way. the infinity prelude mts has an extruded aluminum enclosure, but i am not sure what the baffle itself is made of. doesn't dynaudio's flagship speaker have an aluminum baffle?
Wilson Benesh (sp??) also use aluminium for front baffles too.
I dont understand whats relevent about the reflective nature of a front baffel. After all 99% of loudspeakers have a solid hard front baffle, be it veneered MDF or corian or metal. The only time you see a baffle with felt or foam is when there is a defraction problem that gives rise to a response error, thus adding the foam helps to reduce this effect.
I dont understand whats relevent about the reflective nature of a front baffel. After all 99% of loudspeakers have a solid hard front baffle, be it veneered MDF or corian or metal. The only time you see a baffle with felt or foam is when there is a defraction problem that gives rise to a response error, thus adding the foam helps to reduce this effect.
Using metal for an enclosure can be tricky. I made a small MLTL from 1/4" wall rectangular steel tubing. It has excellent bass but with every vocal confirms why bells are made of steel.
Trying to tame it taught me a lot about constrained layer damping. My next prototype will use a layered front baffle approach, probably three something in the range of 1/16" aluminum and two thin linoluem floor tiles. A single layer of each glued and to the interior walls of the steel line damped resonances immensely (but still not enough.) Stiff, dead and easy to cut.
A another trick that helped a great deal, if you do go metal baffle tap the driver mounting holes and use nylon screws. They transfer much less energy into the baffle.
Trying to tame it taught me a lot about constrained layer damping. My next prototype will use a layered front baffle approach, probably three something in the range of 1/16" aluminum and two thin linoluem floor tiles. A single layer of each glued and to the interior walls of the steel line damped resonances immensely (but still not enough.) Stiff, dead and easy to cut.
A another trick that helped a great deal, if you do go metal baffle tap the driver mounting holes and use nylon screws. They transfer much less energy into the baffle.
Hows about plant pots etc. I was at my local B&Q the other day and looked at the pots. They had some pots that were B&W nautilus shaped. These were about 1" thick out of solid concrete and looked as if they would accomodate a 5 or 6" driver. They were cheapish too about £5 each so for a concrete experiment these would do nicely. Now all i need is some SEAS coax units.
Ill look into Tufnol and corian they sound interesting, especially for an open baffle.
Ill look into Tufnol and corian they sound interesting, especially for an open baffle.
Way back when, we used to use round and rectangular concrete or baked clay drain pipe sections left at building sites.>>
Yes - I made some great speakers out of thick concrete 90 degree bends when I lived in Norway - they have thick stuff there for the icy winters, not earthenware. I have some nice earthenware 90 degree bends outside on the balcony as I speak - I won't use them so free to anybody who picks them up. Kensington, London UK - Andy. Looking into Tufnol!
Yes - I made some great speakers out of thick concrete 90 degree bends when I lived in Norway - they have thick stuff there for the icy winters, not earthenware. I have some nice earthenware 90 degree bends outside on the balcony as I speak - I won't use them so free to anybody who picks them up. Kensington, London UK - Andy. Looking into Tufnol!
simon dart said:
I want to try it, but it seems that tufnol is a brand, is it a kind of Fenolformaldehyde bonded with paper or cotton or something??
Because the cotton bonded (brandname tufnol) is way expensive >540 euro for 1 m X 2 m
The paper bonded is about half that price.
edit: only differences is in the static pressure (150 N/mm2 instead of 170 N/mm2) also in moisture content (8% instead of 2.5%) (hard to translate)
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