Some photos of the woodwork, if anybody is interested:
https://www.flickr.com/photos/44637422@N07/sets/72157647454215496/
Boards are 8mm, bit hard to bend, but they stay well after gluing with couple millimeters of kickback, or what it is called in english.
Curve radius is 750mm.
https://www.flickr.com/photos/44637422@N07/sets/72157647454215496/
Boards are 8mm, bit hard to bend, but they stay well after gluing with couple millimeters of kickback, or what it is called in english.
Curve radius is 750mm.
Sorry, forgot to specify.
Thanks, Lojzek.
It will be passive.
I do not know anything about audio-hifi, but something about woodwork (and mdf) so I thought that this could be my contribution to the site.
I've seen some 909-clones but not really to my taste.
Why clone? Well, design of the baffle and stand is really pleasing to my eye, and I couldn't redraw it any better. However, backsupport is little bit clumsy and I'll chance it's lines a bit. Just few millimeters.
It is bigger in real life than in pictures.
Hmm. I happen to have four 15A's that I intended for a MJK OB. I too have some woodworking skills, so there might be a change of plan about to happen!
I'm thinking about using a vacuum bag against a curved former. What do you think?
Doug
I think you will not get enough power with vacuum. Five good clamps on each side was enough but just... You only need to clamp boards on both edges, not between. Boards are so stiff that you get plenty enough pressure with the tension of boards.
Difficult to explain in foreign language...
And you should not try to add clamps in between, you will only get dents that show very well with glossy paint.
It takes about the same time to make about seventysix flat baffles than to make two curved, but according to my half-scientific calculations they look seventyeight times better...
Second pair would be much faster since all the jigs are done.
Difficult to explain in foreign language...
And you should not try to add clamps in between, you will only get dents that show very well with glossy paint.
It takes about the same time to make about seventysix flat baffles than to make two curved, but according to my half-scientific calculations they look seventyeight times better...
Second pair would be much faster since all the jigs are done.
I'll admit that I haven't yet done any calculations, but I have a pair of Fostex FE168ES and also a pair of Fostex ribbons that could work as a supertweeters. The other alternative for a supertweeter is to use something with a waveguide.
I guess we are both planning to make the baffles as high as they need to be to accommodate the sizes of our drivers?
Doug
I guess we are both planning to make the baffles as high as they need to be to accommodate the sizes of our drivers?
Doug
Yes you are right, vacuum will work when boards are thin enough, maybe 3-4 mm. With these 8mm, or even 6mm, I believe not.
Anyway, with thin boards, or layers, this "clamping only edges"-method does not work. Thin boards are not stiff enough to press themselves in the middle part.
There´s no risk of clampmarks if you make boards 50mm/2" wider both sides.
I made the baffle as close to original as possible. Tweeter is little bit smaller in my design (104mm). Midrange is same size, 146mm and woofer groove is little bigger than alpha, 390mm, so I could upgrade it some day. Some woofers were little bigger, so I have better change to fit them without rerouting the hole.
And I live in Finland.
Anyway, with thin boards, or layers, this "clamping only edges"-method does not work. Thin boards are not stiff enough to press themselves in the middle part.
There´s no risk of clampmarks if you make boards 50mm/2" wider both sides.
I made the baffle as close to original as possible. Tweeter is little bit smaller in my design (104mm). Midrange is same size, 146mm and woofer groove is little bigger than alpha, 390mm, so I could upgrade it some day. Some woofers were little bigger, so I have better change to fit them without rerouting the hole.
And I live in Finland.
Just checking.
So, you're saying the radius across the front of a R909 is 750?
Therefore the radius at the commencement of the layering process will be 750mm less the thickness of the baffle. How thick is the baffle of a R909?
Doug
PS Also, what is the radius of the top edge of the baffle? & are the (side) edges of the baffle parallel to each other? Or are they tapered ... making the baffle as though is is a part cylinder (sectored)?
I read somewhere that the baffle is 43mm thick. And if you look some picture straight from the side, you will notice that the curvature of the front is very close the thickness of the baffle. So, if the baffle is 490 wide, the radius is about 720. I made it 750, inside, to make bending little easier and to get nice, round number. ��
You'll never notice the difference.
Top radius is 930, center being in the middle of the lower woofer.
Sides are curved. 485 at top, 485 at middle of upper woofer, 440 at lower woofer and 400 at the bottom. Measured along the surface. Those measurements are not exact, they depent from the curve.
You'll never notice the difference.
Top radius is 930, center being in the middle of the lower woofer.
Sides are curved. 485 at top, 485 at middle of upper woofer, 440 at lower woofer and 400 at the bottom. Measured along the surface. Those measurements are not exact, they depent from the curve.
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