Corners?
Thanks.
-very nice!
If I round the corners like that, should I compensate for the lost volume?
-add it on at the top maybe?
Thanks.
-very nice!
If I round the corners like that, should I compensate for the lost volume?
-add it on at the top maybe?
Re: Corners?
The rounded corners tale the place of corner deflectors that were left out. The radius is carefully choosen.
dave
Raphael Shaw said:
The rounded corners tale the place of corner deflectors that were left out. The radius is carefully choosen.
dave
Corner Deflectors?
ok.
So, on the normal Demetri with a 167, If I want to round the corners, or at least chamfer them off, would the whole box need to change then?
-I guess so.
I see the dimensions of your "5th Element" version are quite diffferent to the original Demetri.
-does this have to do with the rounded corners?
I really like the look of the 5th Element one. And I'd definitely like to do a SB.
ok.
So, on the normal Demetri with a 167, If I want to round the corners, or at least chamfer them off, would the whole box need to change then?
-I guess so.
I see the dimensions of your "5th Element" version are quite diffferent to the original Demetri.
-does this have to do with the rounded corners?
I really like the look of the 5th Element one. And I'd definitely like to do a SB.
Not at all... rounded off or 45ed corners would just make the transition around the fold smoother... originally we also had a wedge in the middle at the top to further smooth things. At the fequencies of interest it doesn't make much difference (if any) so we left them out to ease construction. Adding them back in would not be a hardship.
dave
dave
planet10 said:
That's a very nice looking speaker Dave! I can see why you went to the trouble of getting it sorted out! What's the sensitivity?
-- Andrew
Finish?
OK.
I'm using 18mm MDF (Supa-Wood). So I need to cover it up somehow.
First option would be a nice gloss finish, in black & white (paint I guess).
I've never done this sort of finish before.
Anyone know how to go about it, or have any different suggestions?
Maybe some tips about which products to use.
-just getting into building. I'll post some pics soon.
OK.
I'm using 18mm MDF (Supa-Wood). So I need to cover it up somehow.
First option would be a nice gloss finish, in black & white (paint I guess).
I've never done this sort of finish before.
Anyone know how to go about it, or have any different suggestions?
Maybe some tips about which products to use.
-just getting into building. I'll post some pics soon.
Re: Finish?
You can't get plywood? MDF is a real compromise IMHO. If you have to, double up the front, back and top.
dave
Raphael Shaw said:
You can't get plywood? MDF is a real compromise IMHO. If you have to, double up the front, back and top.
dave
Drawbacks?
I already have lots of mdf.
what are the drawbacks of using it?
It's very dense and stiff, I would have thought it would be better (sonically) than ply.
maybe I don't have what you call MDF??
I already have lots of mdf.
what are the drawbacks of using it?
It's very dense and stiff, I would have thought it would be better (sonically) than ply.
maybe I don't have what you call MDF??
Re: Drawbacks?
MDF is not very stiff... the reason why i suggest you will need to double things up to get it up to what 18mm baltic birch is.
Here is a thread where i say my piece (there is another thread somewhere where John/MJL21193 finally gets whati'm trying to say)
http://www.diyaudio.com/forums/showthread.php?s=&threadid=98834
Demetriwas designed specifically to take advantage of the properties of many-ply plywood...
If you havea whole bunch of 3 or 4mm mdf, making it out of many layers of that would be better than 2 layers of 18mm.
dave
Raphael Shaw said:
MDF is not very stiff... the reason why i suggest you will need to double things up to get it up to what 18mm baltic birch is.
Here is a thread where i say my piece (there is another thread somewhere where John/MJL21193 finally gets whati'm trying to say)
http://www.diyaudio.com/forums/showthread.php?s=&threadid=98834
Demetriwas designed specifically to take advantage of the properties of many-ply plywood...
If you havea whole bunch of 3 or 4mm mdf, making it out of many layers of that would be better than 2 layers of 18mm.
dave
Re: Drawbacks?
I believe a myth perpetrated by a bunch of big manufacturers because it allowed them to use cheaper, easier to work and finish MDF.
Look at a cross section of hi-end speakers... B&W, Magico (Alon Wolf is quite vocal), Wilson -- any that use MDF go to heroic measures to counter MDFs very real weaknesses.
We can get also all the free MDF we want -- all we use it for bases and some very specific spacers.
dave
Raphael Shaw said:
I believe a myth perpetrated by a bunch of big manufacturers because it allowed them to use cheaper, easier to work and finish MDF.
Look at a cross section of hi-end speakers... B&W, Magico (Alon Wolf is quite vocal), Wilson -- any that use MDF go to heroic measures to counter MDFs very real weaknesses.
We can get also all the free MDF we want -- all we use it for bases and some very specific spacers.
dave
mdf, 1/2 the strength, twice the weight.
The best jbl cabs are made of Baltic Birch Ply.
I'm thinking of using oak ply.
Norman
The best jbl cabs are made of Baltic Birch Ply.
I'm thinking of using oak ply.
Norman
What to do?
I still haven't finished reading the whole discussion.
But I think I'll go ahead and build with MDF for now, anyway.
Then if all goes well I'll build again from ply.
I think it's a good opportunity to make all the mistakes.
What I can do (if it will help) is glue thin, hard carpet to the inside, as a sort of panel-damping measure.
-Would that help in this case?
I still haven't finished reading the whole discussion.
But I think I'll go ahead and build with MDF for now, anyway.
Then if all goes well I'll build again from ply.
I think it's a good opportunity to make all the mistakes.
What I can do (if it will help) is glue thin, hard carpet to the inside, as a sort of panel-damping measure.
-Would that help in this case?
Re: What to do?
It isn't really the damping, but the lack of stiffness (and the energy storage).
You'd be better to laminate the mdf inside and out with arborite -- something garish always seems to work better 😉
dave
Raphael Shaw said:
It isn't really the damping, but the lack of stiffness (and the energy storage).
You'd be better to laminate the mdf inside and out with arborite -- something garish always seems to work better 😉
dave
norman bates said:
At the risk of insulting your intelligence, be wary of the numbers and material of the plywood's crossbands in that oak plywood- many of the veneer finished panels include porous grain / softwood species or even OSB/PB//MDF composites. That's certainly the case in the oak plywood I've seen in a recent pair of a commercial BLH.
This type of panel construction is more than strong enough to meet architectural millwork and office furniture standards, but if your design is targeted around stiffness/weight, your results might be not as expected.
Rather like "Medite" or "Formica", Baltic Birch has become a generic term to describe a type of engineered material that in the first 2 cases are actual trademarked brand names. In the case of the Baltic Birch plywood that's distributed in our local area (Canadian West Coast), the product is manufactured in Russia (hence "baltic") . It's the higher number of thinner laminated ply bands that give the material its strength and stiffness. For example the nominal 3/4" (18mm) sheets have 13plys vs 7 plys for a utility grade "meranti" that we use by the truck load monthly.
Another issue to consider working with this particular product is the 5x5ft sheet size - the breakout yield may not necessarily be any better or worse than 4x8 sheets, but enclosures taller than 60" (such as some of Scottmoose's designs) can be interesting - my board stretcher is only good for a total of about 1" .
While either harder to source, or considerably more expensive than Baltic Birch, there are still a variety of options available for high quality multiple ply plywoods available ( "Apple-ply", "Euro-ply" "Finnish plywood" marine grade ply, etc.)
Re: Re: What to do?
Thanks
-What is 'arborite' ?
So I guess there's not much I can do to the mdf to make it worth while then.
"Pollishing Turds", a friend of mine would call it.
Thanks
planet10 said:
-What is 'arborite' ?
So I guess there's not much I can do to the mdf to make it worth while then.
"Pollishing Turds", a friend of mine would call it.
Re: Re: What to do?
Aah!
-I've just read your explanation of this in the thread about panel material.
planet10 said:
Aah!
-I've just read your explanation of this in the thread about panel material.
Re: Re: Re: What to do?
Don
"Arborite"a term applied to sheet paper mated with resin(s) under heat/pressure to form a glossy,hard smooth material. Think kitchen counter-tops.Raphael Shaw said:
Don
Re: Re: Re: Re: What to do?
"Arborite" is a trademarked brand name of high pressure plastic laminate sheet material. Other well known US brand names would be Formica* , Wilsonart, Nevamar, Pionite.
for the geeks who care (thanks,Nit) , a brief history, thanks to Google:
History
Plastic laminate was first used as an insulating material for industrial products. Its invention is credited to two engineers, Herbert A. Faber and Daniel J. O'Conor. In the early 1900s, these two joined the Westinghouse company in Pittsburgh as part of a dream team of scientists working on insulating material and phenolic laminate resins. Phenolic laminate resins had been developed around this time by the Belgian chemist Leo Baekeland. Baekeland condensed phenol and formaldehyde to produce the first totally synthetic plastic, Bakelite. The material was resistant to heat, water, chemicals, and electric current, thus having the properties to replace hard rubber and shellac for electrical insulation. Baekeland's many experiments included impregnating paper with Bakelite resin and then compressing it under molds at high pressure and temperature in a process known as ther-mosetting. The two Westinghouse engineers worked in this same vein. They began by impregnating heavy canvas with Bakelite resin, and by 1913 they had applied for a patent for a flat laminate sheet made from Bakelite and paper. Faber called the new plastic laminate * formica: "for" (in place of) "mica" (mineral used as electrical insulation material).
Faber and O'Conor left Westinghouse to found their own company in 1913, the Formica Insulating Company in Cincinnati, Ohio. The new company produced rings and tubes of plastic laminate for electrical insulating purposes, but by 1914, Faber and O'Conor were using a press to churn out flat laminate sheets. The laminate was widely used in radio sets in commercial shipping and naval vessels to insulate coils, tuners, and other parts. But plastic laminate was soon used for its decorative properties as well because its flawless, uniform character was the perfect radio exterior. By 1921, the laminate manufactured by the Formica Insulating Company had been integrated into the manufacture of home radios as well as ship radios.
In 1927, Faber and O'Conor discovered that by adding decorative paper through a lithographic printing process, their laminates could be made with patterns that simulated wood grains and marble. As the laminate became more colorful and decorative, its market expanded. Faux marble laminate was popular for soda fountains in the 1930s, and a woodgrain laminate was used in place of aluminum inside airplanes in the 1940 s. Manufacturing improvements soon enabled plastic laminate to resist cigarette burns, and the material became more attractive, colorful, and durable, spurring its use by manufacturers of kitchen and dining furniture.
doorman said:
"Arborite" is a trademarked brand name of high pressure plastic laminate sheet material. Other well known US brand names would be Formica* , Wilsonart, Nevamar, Pionite.
for the geeks who care (thanks,Nit) , a brief history, thanks to Google:
History
Plastic laminate was first used as an insulating material for industrial products. Its invention is credited to two engineers, Herbert A. Faber and Daniel J. O'Conor. In the early 1900s, these two joined the Westinghouse company in Pittsburgh as part of a dream team of scientists working on insulating material and phenolic laminate resins. Phenolic laminate resins had been developed around this time by the Belgian chemist Leo Baekeland. Baekeland condensed phenol and formaldehyde to produce the first totally synthetic plastic, Bakelite. The material was resistant to heat, water, chemicals, and electric current, thus having the properties to replace hard rubber and shellac for electrical insulation. Baekeland's many experiments included impregnating paper with Bakelite resin and then compressing it under molds at high pressure and temperature in a process known as ther-mosetting. The two Westinghouse engineers worked in this same vein. They began by impregnating heavy canvas with Bakelite resin, and by 1913 they had applied for a patent for a flat laminate sheet made from Bakelite and paper. Faber called the new plastic laminate * formica: "for" (in place of) "mica" (mineral used as electrical insulation material).
Faber and O'Conor left Westinghouse to found their own company in 1913, the Formica Insulating Company in Cincinnati, Ohio. The new company produced rings and tubes of plastic laminate for electrical insulating purposes, but by 1914, Faber and O'Conor were using a press to churn out flat laminate sheets. The laminate was widely used in radio sets in commercial shipping and naval vessels to insulate coils, tuners, and other parts. But plastic laminate was soon used for its decorative properties as well because its flawless, uniform character was the perfect radio exterior. By 1921, the laminate manufactured by the Formica Insulating Company had been integrated into the manufacture of home radios as well as ship radios.
In 1927, Faber and O'Conor discovered that by adding decorative paper through a lithographic printing process, their laminates could be made with patterns that simulated wood grains and marble. As the laminate became more colorful and decorative, its market expanded. Faux marble laminate was popular for soda fountains in the 1930s, and a woodgrain laminate was used in place of aluminum inside airplanes in the 1940 s. Manufacturing improvements soon enabled plastic laminate to resist cigarette burns, and the material became more attractive, colorful, and durable, spurring its use by manufacturers of kitchen and dining furniture.
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