3D spiral horn?

[mark_titano]

Hi all. What do you think about this kind of speakers?

http://www3.ocn.ne.jp/~hanbei/eng-whyspiral.html

http://www3.ocn.ne.jp/~hanbei/eng-how.html

http://www3.ocn.ne.jp/~hanbei/eng-boxmodel.html

http://www3.ocn.ne.jp/~hanbei/eng-helixl100.html


I like the Helix L-103( for dimension, looks and cost but I've not experience with diy loudspeakers so I need help to evaluate it ),
in the bottom of this page:

http://www3.ocn.ne.jp/~hanbei/eng-linearmodel.html

Thankyou in advance

Mark

[greenie512]

Glup - I think you are very brave attempting this complex spiral construction as your first speaker project.

I'd start off perhaps with same driver in a simple BR box and if you are happy with driver try a more complex enclosure.?

Fostex get good reviews for full range drivers. I'm going to try one for a new project in a few months but I don't think I'd have the patients to try this spiral port design

Good luck.

[mark_titano]

Well...the great problem is chose the speaker ( I want something with good sensitivity for my diy tube amp) then I'll try different solution, indeed this one will be one of these...and BR too I've some problem with the dimension of the speakers so I'm not sure if a standard BR can have good low frequency response ... This is what I need:

1) sensibility>90 Db ( I want to use good low power amp(5/15W).

2) dimension...I have to lay the loudspeaker on a desk 76cm high. Not a good solution indeed, but this is my condition in this moment. Max dimension: 50*30*30cm

3)cost: 200€ max

Mark

[johninCR]

I was thinking about giving these a shot for my FE206E's. Everything is straight forward construction except the spiral and you don't have to insert it until it's right. To make the spiral I was thinking of stringing a bunch of popsicle sticks on a threaded rod. Put enough pressure that they hold their position. Splay them to form the spiral and tighten it down. A couple of layer of fiberglass resin and fiberglass cloth to stregthen it. Sand the edges for a perfect fit and slide it in.

[mark_titano]

Originally posted by johninCR
I was thinking about giving these a shot for my FE206E's. Everything is straight forward construction except the spiral and you don't have to insert it until it's right. To make the spiral I was thinking of stringing a bunch of popsicle sticks on a threaded rod. Put enough pressure that they hold their position. Splay them to form the spiral and tighten it down. A couple of layer of fiberglass resin and fiberglass cloth to stregthen it. Sand the edges for a perfect fit and slide it in.

Hi johninCR, I'm not sure if I've understand how you think to make the spiral. About the popsicle sticks, you mean to fix one side of them in the screw thread...right? With glue I think... Since the tread pitch isn't the same of the spiral ( that isn't constant too) you can glue the sticks each other ( they are partially laid one at top of the others). Than the fiberglass layers to stregthen the spiral pattern. Ok? I'm right?
It seems straight forward indeed, I'm only afraid by the weight of the rod, that, sooner or later, might warp the spiral or even weaken the sticking. I think we have to consider this aspect. Maybe a good solution will be to carve the way of the spiral on a wood rod and put in the posicle sticks ( you can glue them with vinyl glue). Then you'll use the fiberglass...how does it looks?

Sorry for my bad english...I hope my answer is comprehensible

Mark

[johninCR]

The threaded rod would need to be thin unless you used tongue depressers (like doctors use). Drill a hole near one end. Put them all on the rod. Tighten with nuts and washers on both ends. Line them up uniformly and clamp with a wood clamp. Cut them slightly longer than needed. Sand the ends to the proper length and very slight arc. Maintain the correct amount of pressure with the rod and nuts to splay them into the proper spiral, probably using a little glue as you go. Then proceed. At the end, remove the rod if you want and seal the hole.

Mr. Takenaka told me he thought sealing gap between the spiral and the sidewall of the pipe may be difficult with this method. Small pieces of a thicker wood may be less problematic, but would require more filler to make the spiral very smooth.

Maybe his cable method is easier to get right than it seems. The wood cutout method he shows is far too much work unless you have access to a CNC robotic router. My idea seemed cheap and easy enough to try.

[kneadle]

Has anyone actually critiqued the design theory? I remain skeptical that the spiral does what the author/designer says.

I don't mean to say that it does not do what is said, but I mean to say that I remain skeptical until I see some independent data.

Dave

[mark_titano]

Originally posted by kneadle
Has anyone actually critiqued the design theory? I remain skeptical that the spiral does what the author/designer says.

I don't mean to say that it does not do what is said, but I mean to say that I remain skeptical until I see some independent data.

Dave

Hi kneadle...this is the reason why I post here...I found nothing over this design. I You think someting about plese post your opinion.
So why don't you think the spiral does what the author says?

[kneadle]

The following paragraph on his site concerns me:

A 3D spiral horn has a relatively short three-dimensional spiral horn that looks like a conch shell.
Its structure is comparatively simple. It can be built using standard PVC pipes and fittings. Therefore, you do not need a high degree of technical skills to build.
The most prominent peculiarity of 3D spiral horn is that its lower frequency region extends to 35 Hz using 3" full range driver without booming and without decline of SPL, although I can't understand the mechanism. [emphasis mine]

There are a number of undocumented assertions littered all over the site. Please understand: I am a skeptic, not an unbeliever. It's actually self critique I'm interested in. See my spiral shaped enclosure here.

Dave

[mark_titano]

Originally posted by kneadle

There are a number of undocumented assertions littered all over the site.Please understand: I am a skeptic, not an unbeliever.

True...another reason why I've posted here. None seems to be interested to critique this spiral horn ( or spiral trasmission line? ) Unbeliever or not I hope your critique open the discussion, because I think that this speakers, if they really do what the designer says, will be a good solution for a large number of people. They are small, with good looks and they seems able to reproduce a better LF than a standard bass reflex ( for a fullrange like the Fe127 obviously!). Maybe I'm wrong because I start with diy only last year and my attention since today was for tubes

Originally posted by kneadle
See my spiral shaped enclosure

Dave

Do you mean these?

http://www.t-linespeakers.org/projec...uke/index.html

Mark