Nanook,
You and I are definitely on the same page. I think I'm going to stick with wood slats for the spiral. That way I'll have no air spaces to seal in the spiral. Maybe some molding (cheap and soft wood plus one edge is rounded) then I can mount them all on the rod, clamp it and round the ends with a belt sander all at once to match curve of the tube. Maybe I can get away with no fiberglass work, just an epoxy or fiberglass resin to seal with the tube and a coat on the entire spiral to seal and strengthen. Also as I'm splaying the slats I can use a staple gun on the end of the slats to join them and hold firmly in place.
A thought I had today is to use wider slats and drill the rod holes at steeper and steeper angles so they form the spiral naturally with alot less slats. I couldn't use the threaded rod as a clamp with that method but stapling the ends should be sufficient until resin is applied.
You and I are definitely on the same page. I think I'm going to stick with wood slats for the spiral. That way I'll have no air spaces to seal in the spiral. Maybe some molding (cheap and soft wood plus one edge is rounded) then I can mount them all on the rod, clamp it and round the ends with a belt sander all at once to match curve of the tube. Maybe I can get away with no fiberglass work, just an epoxy or fiberglass resin to seal with the tube and a coat on the entire spiral to seal and strengthen. Also as I'm splaying the slats I can use a staple gun on the end of the slats to join them and hold firmly in place.
A thought I had today is to use wider slats and drill the rod holes at steeper and steeper angles so they form the spiral naturally with alot less slats. I couldn't use the threaded rod as a clamp with that method but stapling the ends should be sufficient until resin is applied.
suggestions :
To construct the spiral, use the rubber belt which is used in ehicles. This type of belt is for linking the engine with dynamo etc.
Just find the right cross section and use it to replace the flat cables used by Mr. T.
As for air-tight problem between the spiral and outer cylinder, suggest to cut the outer cylinder into two halves. Fit the completed spiral into one of the half and glue it properly. then
cover with the other half. Glue the halves together.
kb
Dynamo?
I am not familiar with the "This type of belt is for linking the engine with dynamo etc." Can you be more specific?Picture maybe? I have constructed two horns using Masaki's method and it really isn't hard to do, but it is time consuming so any shortcut to the process would be cool.
Thanks.
If anyone is interested I am using the 4.5" vifa buyouts with Massaki's horn design in an approx. 7.2 liter box. I am very impressed with the quality of bass. They are not real loud players but they do sound quite excellent in the office.
I am not familiar with the "This type of belt is for linking the engine with dynamo etc." Can you be more specific?Picture maybe? I have constructed two horns using Masaki's method and it really isn't hard to do, but it is time consuming so any shortcut to the process would be cool.
Thanks.
If anyone is interested I am using the 4.5" vifa buyouts with Massaki's horn design in an approx. 7.2 liter box. I am very impressed with the quality of bass. They are not real loud players but they do sound quite excellent in the office.
Eddog,
He's talking about a fan belt, which might be a little easier since it's flat. You need the right glue though.
Cutting in half lengthwise won't help much. You'll have the same sealing problem as before with areas you can't reach. Cutting by sections of length is more pratical so you can get to all of the spiral edges for sealing.
He's talking about a fan belt, which might be a little easier since it's flat. You need the right glue though.
Cutting in half lengthwise won't help much. You'll have the same sealing problem as before with areas you can't reach. Cutting by sections of length is more pratical so you can get to all of the spiral edges for sealing.
It is NOT horn!
http://www3.ocn.ne.jp/~hanbei/eng-linearmodel.html
it is not 3D-horn!
3D horn must be tractrix shape, not cylinder!
http://www3.ocn.ne.jp/~hanbei/eng-linearmodel.html
it is not 3D-horn!
3D horn must be tractrix shape, not cylinder!
Not a spiral horn...
well guys finally some semantics...
the spiral horn or 3D horn or whatever you want to call is a tube with an expanding "horn" contained within it.
In reality the tube that Mr. Takenaka uses as a tuned "port" IS the spiral horn.
In Mr. Takenake's case, he uses the horn as a Helmholtz resonator , and "amplifies" the resonant frequency by tuning the horn contained within it to the Helmholtz frequency of the "port". I think a very creative idea and I have modelled the behaviour (but as CR has indicated perhaps not too elegantly or with much clarity).
I think that the real benefits are:
1) creating a bass reflex design with good bass extension from a small enclosure and small full range driver;
2) and the possibility of creating a LONG horn in a small and somewhat convenient shape such as a cyclinder.
Enough semantics. The end result will be the true test.
well guys finally some semantics...
the spiral horn or 3D horn or whatever you want to call is a tube with an expanding "horn" contained within it.
In reality the tube that Mr. Takenaka uses as a tuned "port" IS the spiral horn.
In Mr. Takenake's case, he uses the horn as a Helmholtz resonator , and "amplifies" the resonant frequency by tuning the horn contained within it to the Helmholtz frequency of the "port". I think a very creative idea and I have modelled the behaviour (but as CR has indicated perhaps not too elegantly or with much clarity).
I think that the real benefits are:
1) creating a bass reflex design with good bass extension from a small enclosure and small full range driver;
2) and the possibility of creating a LONG horn in a small and somewhat convenient shape such as a cyclinder.
Enough semantics. The end result will be the true test.
Ok Variac..
Yes, that idea was presented on Mr. Takenaka's website (of a sort) using his disk method.
I believe another way maybe to sink dowels into the centre support and attach "fins" as you suggest to the dowels. The could easily be trimmed to fit the ajacent "fins" and trimmed to the finished outside dimention. When completed glue the fins together and let set. Glue completed spiral units inside the tubes or use threaded rod with tne caps so that they could eaily be removed.
stew
Yes, that idea was presented on Mr. Takenaka's website (of a sort) using his disk method.
I believe another way maybe to sink dowels into the centre support and attach "fins" as you suggest to the dowels. The could easily be trimmed to fit the ajacent "fins" and trimmed to the finished outside dimention. When completed glue the fins together and let set. Glue completed spiral units inside the tubes or use threaded rod with tne caps so that they could eaily be removed.
stew
Variac,
Front horn, rear horn shouldn't matter. One of us just needs to be the guniea pig to build a larger version. The only question in my mind is will the spiral horn passageway distort the sound. I wish sonotube was available down here, because it would make the project a lot easier and cheaper than large diameter PVC.
Front horn, rear horn shouldn't matter. One of us just needs to be the guniea pig to build a larger version. The only question in my mind is will the spiral horn passageway distort the sound. I wish sonotube was available down here, because it would make the project a lot easier and cheaper than large diameter PVC.
Sonotube sounds perfect to me. They do so much stuff out of concrete in C.R. I would sure think that it is available somewhere. I'll try to ask my bro in law there who is in the construction biz.
the curved path is worrisome, but I've seen those mid/high metal horns with more than a complete loop in them so maybe its OK, and probably better than folded horns that not only curve but have abrupt transitions.
the curved path is worrisome, but I've seen those mid/high metal horns with more than a complete loop in them so maybe its OK, and probably better than folded horns that not only curve but have abrupt transitions.
Well johninCR, I will answer you here mainly to give this fascinating thread a bump. Apparently you did your homework well, they don't use sonotube in Costa Rica. They instead use corrugated steel tube like we use for culverts, and leave it in place, which acts like reinforcing.
I guess you will have to fabricate a tube out of layers of veneer-what a pain!! Or maybe sheet metal and then coat it with thick damping material. anyone have any input on how the different path lengths of the spiral affects the sound? MAybe it all just averages out....
Mark
I guess you will have to fabricate a tube out of layers of veneer-what a pain!! Or maybe sheet metal and then coat it with thick damping material. anyone have any input on how the different path lengths of the spiral affects the sound? MAybe it all just averages out....
Mark
I've heard for making columns like for a home they'll use large diameter PVC as the form, then cut the PVC off. I was hoping to get some kind of industrial contact as a source for sonotube via your brother. Oh well.
A roll of thick paper and spray glue would probably be the easiest method of construction anyway once you have the spiral done, although the 5ft section of 12" pvc I have might be enough volume for an 8-10" driver bass horn. Just add a mouth extension for the terminous. I just have too many projects planned that my procrastination results in not starting any of them including a trial run at building a spiral.
A roll of thick paper and spray glue would probably be the easiest method of construction anyway once you have the spiral done, although the 5ft section of 12" pvc I have might be enough volume for an 8-10" driver bass horn. Just add a mouth extension for the terminous. I just have too many projects planned that my procrastination results in not starting any of them including a trial run at building a spiral.
With those kind of diameters, I'd slice out some V shaped sections out lengths of sonotube to form conical sections for a nice simple straight or curved bass horns. Use epoxy and fiberglass cloth for the seams. Now I'm really upset that there's no sonotube down here. Time to go back stateside.
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