It's seems what is being sought is some emperical evidence that this design works better than other applications of TL/horn theory. So far (IMHO) what I see is a very clever way to get a long mass loaded line in a small package. What would be really cool would be to make it all out of Plexiglas 
Timn8ter said:It's seems what is being sought is some emperical evidence that this design works better than other applications of TL/horn theory. So far (IMHO) what I see is a very clever way to get a long mass loaded line in a small package. What would be really cool would be to make it all out of Plexiglas
Hi Tim... how would you make the spiral using plexy?
Mark
I think he meant a plexy cab and clear tube, then a colored spiral to make it really stand out. Using uniform, short, fat spirals for ports would be really nice for those subs that you can see inside.
I was thinking, to get a perfect seal around your spiral and a non resonant tube, just use posterboard to wrap around it to form the tube. Glue and seal the first turn well. Then keep rolling paper or whatever to get the thickness and strength you want. Since it's round, it wouldn't need to be overly thick to be very strong.
I was thinking, to get a perfect seal around your spiral and a non resonant tube, just use posterboard to wrap around it to form the tube. Glue and seal the first turn well. Then keep rolling paper or whatever to get the thickness and strength you want. Since it's round, it wouldn't need to be overly thick to be very strong.
3d spiral horn...
I've "torn apart" the concept behind the spiral horn and have to say that if this was a seredipitous (accidental) finding or creative thought, what a thought. I've looked at the mathematics and believe that these spiral horns are an academically correct idea, even though Mr. Takenaka seems unsure of what is really going on with his loudspeakers (or just isn't letting on).
By academically correct I mean that the concept seems reasonable and the speaker can be designed following a cookbook method if you understand the concept. I am not however suggesting that the results are musical, but 50Hz from a Fostex FE127E or FE103 certainly is very appealing. I believe that these would certainly be an interesting idea and may infact be very musical
I am planning on putting some FE127Es into a 11.65 litre box and constructing the "spiral" horn for use with a Sonic Impact "T" amp or Teac Tripath amp. When (if) I get around to it, I'll certainly post my impressions.
I've "torn apart" the concept behind the spiral horn and have to say that if this was a seredipitous (accidental) finding or creative thought, what a thought. I've looked at the mathematics and believe that these spiral horns are an academically correct idea, even though Mr. Takenaka seems unsure of what is really going on with his loudspeakers (or just isn't letting on).
By academically correct I mean that the concept seems reasonable and the speaker can be designed following a cookbook method if you understand the concept. I am not however suggesting that the results are musical, but 50Hz from a Fostex FE127E or FE103 certainly is very appealing. I believe that these would certainly be an interesting idea and may infact be very musical
I am planning on putting some FE127Es into a 11.65 litre box and constructing the "spiral" horn for use with a Sonic Impact "T" amp or Teac Tripath amp. When (if) I get around to it, I'll certainly post my impressions.
More spiral horns:
http://www.cornu.de/minispir_t.html
Even if you don´t get the german, there are some interesting pics on the site. The speakers get very good reviews (especially the small spiral with a Veravox3)
http://www.cornu.de/minispir_t.html
Even if you don´t get the german, there are some interesting pics on the site. The speakers get very good reviews (especially the small spiral with a Veravox3)
Nanook,
How do you figure out the horn length?
I'm thinking about using the concept to build a real horn. Imagine the potential of a 2m piece of 18" or larger sonotube. Cut a bunch of slats and thread them on a rod. Splay them to form your spiral and glue them in place (with a thick epoxy resin to smooth and strengthen the spiral at the same time). Cut the sonotube in sections, so you can reach inside to seal the edges of the spiral with the sonotube. Seal the sections together as you go. Make a circular baffle and slide it in to a predetermined position. Put on the end cap wrap the tube in some material and you're done. For other than corner placement you may want to make a mouth extension.
A 3 or 4 meter basshorn that's cheap and easy to build (no folds to fit in a box), virtually indestructible (if you use PVC), lightweight enough to carry under one arm and probably needs only an 8" or 10" driver for some pretty serious output.
How do you figure out the horn length?
I'm thinking about using the concept to build a real horn. Imagine the potential of a 2m piece of 18" or larger sonotube. Cut a bunch of slats and thread them on a rod. Splay them to form your spiral and glue them in place (with a thick epoxy resin to smooth and strengthen the spiral at the same time). Cut the sonotube in sections, so you can reach inside to seal the edges of the spiral with the sonotube. Seal the sections together as you go. Make a circular baffle and slide it in to a predetermined position. Put on the end cap wrap the tube in some material and you're done. For other than corner placement you may want to make a mouth extension.
A 3 or 4 meter basshorn that's cheap and easy to build (no folds to fit in a box), virtually indestructible (if you use PVC), lightweight enough to carry under one arm and probably needs only an 8" or 10" driver for some pretty serious output.
how do you calculate the "horn"?
er pretty easy.. ok maybe not real easy..
an example may be the best way to illustrate the idea.
The horn length can be calculated as follows.
Determine the "tube" length and diameter. Your example 48" long, 18" diameter
Determine the area required behind the driver ("So" or throat area), Using known horn theory, Calculate some ("Sd" or mouth area). Start with something in the neighdourhood of (Sd/So)=1.5 or 2.0
Make a couple of assumptions. The inside rod or support structure has some dimention, say 1" (maybe threaded rod?) as an example.
Determine how many rotations about the tube the "horn" has to make to get the desird length. The horn "width" is = (18"-1")/2=8.5 inches^2. The horn throat should be the same area as area of the radiating surface of the driver or larger,
You have set "mouth area", Sd to=1.5 So or 2.0 So. If you don't want to do the math, basically measure from the top of the tube down some distance, so that the area So is satisfied. Measure from the bottom up so that Sd is satisfied. (remember to take into acount the thickness of material used to create the horn ) divide each distance (those that are marked "down, and marked "up") by 2 and make a mark. Wrap some string around the sonotube from the So midpoint and the Sd midpoint. perhaps once or 1.5 times or 2 or whatever. Measure the string length. This will give you an idea of whether or not the "horn" will fit the tube.
I played around with the mathematics of this for a couple of weeks in January.
The length of the horn can be calculated once you determine how many times the horn "rotates" about the centre support as follows :
[(midpoint So - midpoint Sd)^2 + (number of "rotations"*Pi*D)^2]^(1/2)
Using Mr Takenaka's data from his site I was able to calculate a 49.7 (almost 20") centimeter horn length from a 10cm (3.9") ID tube of length 32.5 cm (9.6") with So=37 cm^2 and Sd =56 cm^2 (I put Sd/So= 1.5 approximately). Remember however So and Sd are artificially small as Mr. Takenaka is not loading the horn directly from the driver.
Someplace I may have a CAD drawing I used to help me visualize the concept. good luck. email me if you have further questions (I can't say that my post has what I call clarity in explaination:-( )
er pretty easy.. ok maybe not real easy..
an example may be the best way to illustrate the idea.
The horn length can be calculated as follows.
Determine the "tube" length and diameter. Your example 48" long, 18" diameter
Determine the area required behind the driver ("So" or throat area), Using known horn theory, Calculate some ("Sd" or mouth area). Start with something in the neighdourhood of (Sd/So)=1.5 or 2.0
Make a couple of assumptions. The inside rod or support structure has some dimention, say 1" (maybe threaded rod?) as an example.
Determine how many rotations about the tube the "horn" has to make to get the desird length. The horn "width" is = (18"-1")/2=8.5 inches^2. The horn throat should be the same area as area of the radiating surface of the driver or larger,
You have set "mouth area", Sd to=1.5 So or 2.0 So. If you don't want to do the math, basically measure from the top of the tube down some distance, so that the area So is satisfied. Measure from the bottom up so that Sd is satisfied. (remember to take into acount the thickness of material used to create the horn ) divide each distance (those that are marked "down, and marked "up") by 2 and make a mark. Wrap some string around the sonotube from the So midpoint and the Sd midpoint. perhaps once or 1.5 times or 2 or whatever. Measure the string length. This will give you an idea of whether or not the "horn" will fit the tube.
I played around with the mathematics of this for a couple of weeks in January.
The length of the horn can be calculated once you determine how many times the horn "rotates" about the centre support as follows :
[(midpoint So - midpoint Sd)^2 + (number of "rotations"*Pi*D)^2]^(1/2)
Using Mr Takenaka's data from his site I was able to calculate a 49.7 (almost 20") centimeter horn length from a 10cm (3.9") ID tube of length 32.5 cm (9.6") with So=37 cm^2 and Sd =56 cm^2 (I put Sd/So= 1.5 approximately). Remember however So and Sd are artificially small as Mr. Takenaka is not loading the horn directly from the driver.
Someplace I may have a CAD drawing I used to help me visualize the concept. good luck. email me if you have further questions (I can't say that my post has what I call clarity in explaination:-( )
Nanook,
Wrapping the string around the tube is going to result in a very exagerated horn length. At the outer edges of the spiral the length is quite long but near the center the length is not much longer than tube. I was hoping you had a formula to compute the average cross sectional path length.
I'm thinking that the best way to get the desired horn is compute the volume of the straight horn I want and allocate that volume of tube to use for the horn plus an adjustment for the estimated volume of taken up by the spiral. The mouth is easy, the cross sectional area of the tube. The throat is easy to achieve and is the cross sectional area at the first full turn of the spiral. That's where the pathway becomes enclosed. Then I will expand the spiral spacing at the expansion rate of the straight horn I want.
The mouth size is pretty much going to require corner loading, but I'm sure I can come up with a conical extension after I prove that the concept works well.
Wrapping the string around the tube is going to result in a very exagerated horn length. At the outer edges of the spiral the length is quite long but near the center the length is not much longer than tube. I was hoping you had a formula to compute the average cross sectional path length.
I'm thinking that the best way to get the desired horn is compute the volume of the straight horn I want and allocate that volume of tube to use for the horn plus an adjustment for the estimated volume of taken up by the spiral. The mouth is easy, the cross sectional area of the tube. The throat is easy to achieve and is the cross sectional area at the first full turn of the spiral. That's where the pathway becomes enclosed. Then I will expand the spiral spacing at the expansion rate of the straight horn I want.
The mouth size is pretty much going to require corner loading, but I'm sure I can come up with a conical extension after I prove that the concept works well.
Exagerated horn length
The idea of the string is really just to give you an idea if the horn will fit the "tube" if you don't want to do the math to start.
The calculations (near the bottom of my previous post) result in a horn length that is within 1/2 % of reality (remember in the calculation the inside diameter of the sonotube is used). I'll try to find the CAD drawing I did.
The idea of the string is really just to give you an idea if the horn will fit the "tube" if you don't want to do the math to start.
The calculations (near the bottom of my previous post) result in a horn length that is within 1/2 % of reality (remember in the calculation the inside diameter of the sonotube is used). I'll try to find the CAD drawing I did.
Nanook,
I'm sorry, I skipped over the calculation when the result didn't feel right, but I wasn't considering that the initial part of the tube is used to create the throat and isn't part of the actual horn length. Plus on the smaller versions it's so few rotations.
I still think using the overall volume of the desired horn compared to the tube volume should be my starting point. The clear advantages would be the relative ease of design and construction (yes definitely a threaded rod so you can easily apply pressure so the slats stay in place while splaying them into the spiral), having no flat surfaces (no panel resonances), and overall weight (due to the thin lightweight but strong exterior).
The big question in my mind is whether the spiral itself will distort the signal due to the differing pathway lengths close to the center vs near the edge.
Unfortunately I've been unsuccessful in locating any sono tube down here. I do have a piece of 12" PVC that's just over 3 cu ft which might be enough for a 6" or 8" driver as a test.
I'm sorry, I skipped over the calculation when the result didn't feel right, but I wasn't considering that the initial part of the tube is used to create the throat and isn't part of the actual horn length. Plus on the smaller versions it's so few rotations.
I still think using the overall volume of the desired horn compared to the tube volume should be my starting point. The clear advantages would be the relative ease of design and construction (yes definitely a threaded rod so you can easily apply pressure so the slats stay in place while splaying them into the spiral), having no flat surfaces (no panel resonances), and overall weight (due to the thin lightweight but strong exterior).
The big question in my mind is whether the spiral itself will distort the signal due to the differing pathway lengths close to the center vs near the edge.
Unfortunately I've been unsuccessful in locating any sono tube down here. I do have a piece of 12" PVC that's just over 3 cu ft which might be enough for a 6" or 8" driver as a test.
Re: last thoughts
They are expo "horns". The space between the spirals (ie cross sectional area) increases exponentially. The throat starts as the area formed by the area at the first full turn and expands essentially to the full area of the tube.
The modelling I did with HornResp showed a broad low end response hump, but sharp peaks in response above 100hz. I think this was due to such a short horn lenght combined with a large chambered RLH. Based on Mr. T's info, somehow the setup must filter out the peaks created by such a short horn. What I want to try first is to increase the size and take the concept up to bass horn size.
kita said:
They are expo "horns". The space between the spirals (ie cross sectional area) increases exponentially. The throat starts as the area formed by the area at the first full turn and expands essentially to the full area of the tube.
The modelling I did with HornResp showed a broad low end response hump, but sharp peaks in response above 100hz. I think this was due to such a short horn lenght combined with a large chambered RLH. Based on Mr. T's info, somehow the setup must filter out the peaks created by such a short horn. What I want to try first is to increase the size and take the concept up to bass horn size.
A "sonotube" horn...
John,
I think I should just post the CAD file (or convert it to something a little easier for some to view).
Mr. Takenaka had created a "popsicle stick" type horn in one of his smallest designs, basically stacked discs with a "C" cut out of them.
Mr. Takenaka's "disk" method
stew
John,
I think I should just post the CAD file (or convert it to something a little easier for some to view).
Mr. Takenaka had created a "popsicle stick" type horn in one of his smallest designs, basically stacked discs with a "C" cut out of them.
Mr. Takenaka's "disk" method
stew
thanks john
I appreciate that the 'intervals' between each turn get longer as you move down the spiral axis in Mr T's, but I was wondering what affect an increase in the diameter of the spiral would have on the sonics- so that the case would look like a cone shell rather than a straight pipe?
sorry if i wasn't clear
I appreciate that the 'intervals' between each turn get longer as you move down the spiral axis in Mr T's, but I was wondering what affect an increase in the diameter of the spiral would have on the sonics- so that the case would look like a cone shell rather than a straight pipe?
sorry if i wasn't clear
I don't even know yet if the straight pipe spiral impacts the sonics. If anything, a cone shaped would be even better because less turns would be needed. If I had an easy way to make cone shaped tubes, then I'd just make a horns by connecting different cone segments together. If you think of an easy way to make a cone and then make a spiral to fit it, please let me know.
the hard way or the hard way...
no easy way but two fairly awkward possibilities-
Stick with the tongue depressor/ popsicle stick and fibregalss method but exponentially increase the lengths of the 'ribs'. this could build the 'inside' of a cone shell, but It still would require a snug fitting cone enclosure and I'm stuck for ideas on that.
alternatively something like the serpahim (http://www.t-linespeakers.org/projects/davidduke/index.html) could be built with sections of increasing diameter pipe. The main prob with this is that apart from the complexity of the construction it is likely to resonate..... I guess this could be fixed partially by reinforcement/ damping, or once and for all by using it as a mould for a huge plaster of paris casting which would probably never move again. Possibly could be incoroporated in the design of a new build house but now I'm drifitng off to space...
more (and more practical) ideas please! I think its worth fighting for
no easy way but two fairly awkward possibilities-
Stick with the tongue depressor/ popsicle stick and fibregalss method but exponentially increase the lengths of the 'ribs'. this could build the 'inside' of a cone shell, but It still would require a snug fitting cone enclosure and I'm stuck for ideas on that.
alternatively something like the serpahim (http://www.t-linespeakers.org/projects/davidduke/index.html) could be built with sections of increasing diameter pipe. The main prob with this is that apart from the complexity of the construction it is likely to resonate..... I guess this could be fixed partially by reinforcement/ damping, or once and for all by using it as a mould for a huge plaster of paris casting which would probably never move again. Possibly could be incoroporated in the design of a new build house but now I'm drifitng off to space...
more (and more practical) ideas please! I think its worth fighting for
A "sonotube" horn...
Maybe a cylinder is less efficient in terms of "packaging", but the ease of construction and the gradual taper possible will make a speaker closer approximating a true horn rather than fitting a horn to a rectangular structure(with all of the bends and complicated wood working and construction methods required to build a good enclosure).
As for building the "spiral" I have been thinking about a plastic conduit over a threaded rod, secured with nuts on either way. Carefully drill small holes perpendicular to the conduit and glue dowels to the conduit. Run fibreglass weaved CLOTH (as opposed to cloth made of chop). Fibreglass "core board" could be used to create an absolutely strong fibreglass spiral. Once made, the edges could be trimmed to fit the sonotube tightly.
Remeber to wear a mask when trimming cured fibreglass as the particles can cause very real difficulties to your lungs longterm.
stew
Maybe a cylinder is less efficient in terms of "packaging", but the ease of construction and the gradual taper possible will make a speaker closer approximating a true horn rather than fitting a horn to a rectangular structure(with all of the bends and complicated wood working and construction methods required to build a good enclosure).
As for building the "spiral" I have been thinking about a plastic conduit over a threaded rod, secured with nuts on either way. Carefully drill small holes perpendicular to the conduit and glue dowels to the conduit. Run fibreglass weaved CLOTH (as opposed to cloth made of chop). Fibreglass "core board" could be used to create an absolutely strong fibreglass spiral. Once made, the edges could be trimmed to fit the sonotube tightly.
Remeber to wear a mask when trimming cured fibreglass as the particles can cause very real difficulties to your lungs longterm.
stew
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