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Old 25th March 2010, 03:24 AM   #1
heyday is offline heyday  United States
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Default Spiral Tapped Horn Invention Box and questions

http://www.audioxpress.com/magsdirx/...olbrek2884.pdf
http://www.audioxpress.com/magsdirx/...olbrek2885.pdf

I have read the above two articles on horn theory and quite frankly, it is moxtly over my head. I was very interested in the fact that when it comes to sound propagation, especially when it comes to horns, it is mostly theory.

While researching horns, (due to my interest in tapped horns) I recall a discussion here in this forum where Tom Danley was discussing antenna theory and whether it might apply to sound waves as well.

I would interject here based upon prior antenna theory research to propose that in antenna theory, a 5/8ths wavelenth antenna design is considered superior ro any other length, whether receiving or transmitting. At least according to some views.

(What is a waveguide, btw? Is it a form of antenna that a soundwave responds to?)

Could it be that the designer here Why building Spiral Horn Speaker? has invented a soundwave antenna, per se?
Patent here:
Speaker system with a three-dimensional spiral sound passage Masaaki Takenaka
Speaker system with a three ... - Google Patent Search

(Perhaps more information may be had by reading this patent also...
Electronic horn with spiral deflecting walls coupled to a truncated cone ...
Electronic horn with spiral ... - Google Patent Search
I haven't read it yet...)

Some posted experimental results:

AudiogoN Forums: Spiral Horn

A full range spiral project here:
The FR125-Spiral project has begun!

I have an idea on building a box that could be easily reconfigured for different horn segment lenths, tapers, etc that one could conduct spiral based experoments with.

Do knowledgeable members have any opinions regarding the feasabilty of success in such an endeavor?

Questions:

1.) Might a bass enclosure size be lessened even more by crossing spiral horn technology with tapped horn design?

2.) Might a spiral placed in a chamner that allowed air/sound to pass by the lengthening spiral act as an antenna "Catching" lower frequency waves even as it allowed shorter soundwaves to pass by, perhaps increasing the frequency response of the tapped horn?

3.) Could such experoments provide date that at the very least could be incorporated into Hornresp with fairly accurate sims so as to eliminate the physical experomentation propr to implementing a well planned design?

4.) And etcetera

Just wondering what other opinions are towards this line of thinking.

Thanks!
Dane
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Old 25th March 2010, 03:57 AM   #2
heyday is offline heyday  United States
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I tried to fix typos and spelling errors but my time to do so had expired
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Old 25th March 2010, 01:23 PM   #3
MaVo is offline MaVo  Germany
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1) No. For bass enclosures, the volume is a very important value, as you change the volume, you change the tuning.
2) No. For the size of wavelengths we are talking about, such a spiral is pretty much invisible for the sound, as it is much too small. It would have no different effect on the sound than a similar sized horn segment without a spiral.
3) No. Hornresp can simulate 4 straight segments, and to be honest, thats all you need.

EDIT for explanation: The spiral is just another way to fold a horn. Its a fancy looking way, but it works like all the other folding schemes, except that it is much more difficult to build.

Last edited by MaVo; 25th March 2010 at 01:31 PM.
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Old 25th March 2010, 02:22 PM   #4
JLH is offline JLH  United States
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Quote:
Originally Posted by MaVo View Post
1)Its a fancy looking way, but it works like all the other folding schemes, except that it is much more difficult to build.
Spot on MaVo.

Rgs, JLH
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Old 26th March 2010, 02:28 AM   #5
heyday is offline heyday  United States
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Quote:
Originally Posted by MaVo View Post
1) No. For bass enclosures, the volume is a very important value, as you change the volume, you change the tuning.
2) No. For the size of wavelengths we are talking about, such a spiral is pretty much invisible for the sound, as it is much too small. It would have no different effect on the sound than a similar sized horn segment without a spiral.
3) No. Hornresp can simulate 4 straight segments, and to be honest, thats all you need.

EDIT for explanation: The spiral is just another way to fold a horn. Its a fancy looking way, but it works like all the other folding schemes, except that it is much more difficult to build.
OK. I can accept that as being a reasonable and correct explanation.

But, is it not true that:

If one had a cylinder, say, 10' in length, and a spiral was introduced into the tube so that the windings of the spiral added up to an arbitrary lenth of 15', (increasing the flare rate as shown by the patent holder), that one would have effectivly increased the length of the cylinder to an additional half length as well as transformed the straight tube into a tapered flare so as to meet the requirements necessary for a horn configuration?

That is, assuming that the spiral construction matched the theoretical parameters that would allow the horn to perform well?

Thanks!

Dane
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Old 26th March 2010, 03:09 AM   #6
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Yes, but... there is no free lunch. You would also have decreased the cross-sectional area of the tube / horn.
Take a 10 foot tube, say 1 square foot cross sectional area, making it 10 cubic feet volume. Now add a spiral, for simplicity make it constant area rather than tapered, that makes the effective length 20 feet. But this 20 foot length has to fit in the same volume as the 10 foot length, so the cross sectional area of the "spiral tube" is now only 0.5 square foot. For a horn (tapped or otherwise), cross sectional area is as important as the length.

In short, a spiral horn will (in theory) perform the same as a straight horn of the same length and volume. If you want to fit a 20 foot horn into a 10 foot length, it's much simpler to fold it in half than form it into a spiral.
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Old 26th March 2010, 03:49 AM   #7
heyday is offline heyday  United States
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OK, understood.

Upon reexamining the issue I had independantly came to a similar conclusion, which is basically an amplification of the above given explanation that a spiral folding is just another method of folding a horn, though more complicated and harder to design.

I understand that the alleged improvements to sound as relayed in my above posted references were said to have been held by using the spiral in vented ports, both rectangular and spherical, but, non-the-less, claims have been made that the spiral foldings did indeed create improvements.

My question, and I know I'm basically illiterate on the subject, is how?

In the first pdf referenced in my first post in this thread, on page 6 (pdf page 6) under the heading "Termination of the Horn" information is provided as follows:
Quote:

[...]

Consider a wave of long wavelength
16. While it is progressing along a tube, it occupies a constant volume, but when it leaves the tube, it expands into an approximate hemispherical shape (Fig. 8). The volume thus increases, the pressure falls, increasing the velocity of air inside the tube, pulling it out. This produces an impulse that travels backwards from the end of the tube, a reflection.
Is it possible that a wavefront, traveling upon an air mass that has been induced into a vortex by a spiral design. might be inclined to exit the horn without such a reflection/backward travelling impulse?

Thanks for your indulgence of a nube!

Dane
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Old 26th March 2010, 10:30 AM   #8
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Quote:
Originally Posted by heyday View Post
Is it possible that a wavefront, traveling upon an air mass that has been induced into a vortex by a spiral design. might be inclined to exit the horn without such a reflection/backward travelling impulse?
Er... No.

Dealing with the wavefront case, a wavefront is sensitive only to the cross-sectional area of the duct. (For most practical purposes.) It will expand at the mouth just as it does in a straight duct.

For the case of air flowing through the duct, it will cease to spiral as it reaches the opening - it will come out in the direction it was travelling when it reached the opening and then proceed in a straight line.
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Old 26th March 2010, 11:06 PM   #9
heyday is offline heyday  United States
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I see...

Hmmmm.

I guess this calls for more research at this point. With your answers in mind, I think I will review my accumulated research on the alleged and claimed sound improvements of this so called spiral horn technology to see if there is some snake oil here or, if not, maybe some clues towards the mechanisms at work.

I'll be posting as many relevant points as I can think of as I continue this study.

Regards,

Dane
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Old 27th March 2010, 12:35 AM   #10
MaVo is offline MaVo  Germany
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If you do the research for fun, then fine. If you hope to get results that will lead to a good speaker, then forget spiral horns, as they have no benefit. Its all snake oil.
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