Paper horns.

[Dr Ken]

Thread split from Introductions
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Right now, I'm transfixed by front loaded horn design. This guy has such nice ideas, both in materials and construction method:

The Paper Horn by Inlow Sound - The Paper Horn
DIY Paper Horn - The Paper Horn by Inlow Sound

I'm intrigued by methods of fabrication: Back in Victorian times, the big thing was clever use of linkages to mechanically solve industrial problems. Linkages can be used to scribe out pure geometries. For example, a set of pivoting lever-arms which would perfectly scribe out a particular shape, like an ellipse, etc. I would like to figure out a method of scribing a tractrix shape via a set of linkages. Given that a tractrix curve is mathematically derived, one just has to figure a practical/mechanical method of describing the curve, then dial it in. This would essentially act as a jig for fabrication.

Right now it's all cerebral without much to show for it... and time looking through wikipedia for inspiration.
Any thoughts?

Oh and thanks Pano for the heads up on the estate sale and Triode group... I'll shoot you a PM -K

 

[Pano]

I made a pair of paper maché horns once. Ugly looking things they were. But sounded great. Very neutral, natural sounding. I used heavy, 100% coton watercolor paper and wheat wallpaper paste.

It's a lot of work.

 

[Dr Ken]

Hehehe. Before seeing that guy's photos, I had no idea that there was a such a refined outcome of paper maché. How did you actually form your horn, Pano? Via a similar mould and geometry?

 

[Pano]

No, I cut "petals" like the old Victrola horns. Taped those together and started piling on the layers. They started out rather pretty, but quickly got messy.

But I think doing a quick practice run or two, that one could achieve very nice results this way. A 4 sided horn would be even easier.

 

[planet10]

A tractrix is the shape defined by a hanging rope, chain. Fix one end, and have the other end moveable, and be able to vary the length. TO my mind, easier to well define in a SS thou.

dave

 

[ra7]

I have heard John's horns... they are quite phenomenal. Downright realistic. Never heard voices that sounded more real... almost palpable. They easily play to 400 Hz.

John's a fantastic guy too. I'll be building some horns with him soon. Should be fun.

 

[Zen Mod]

Mr. Inlow is our wakoo Carpenter ;

I miss him lately - he isn't active on board as before ;

 

[carpenter]

Mr. Inlow is our wakoo Carpenter ;

I miss him lately - he isn't active on board as before ;

I love you guys and do read the threads. I just don't have time to contribute at the moment. The economy keeps contractors like me running in circles -- bills have to be paid, etc.

 

[Dr Ken]

A tractrix is the shape defined by a hanging rope, chain. Fix one end, and have the other end moveable, and be able to vary the length. TO my mind, easier to well define in a SS thou.

dave

I'm not very mathematically minded, but it seems a catenary curve would only approximate a tractrix curve under the very specific condition of the ends approaching their asymptote... a hung string would almost never assume a tractrix curve.

Forgive my ignorance, but what is a "SS" ?

 

[Zen Mod]

nice to know that you are well ........ even if chasing your own tail ( like we all others do, anyway )

 

[planet10]

I'm not very mathematically minded, but it seems a catenary curve would only approximate a tractrix curve under the very specific condition of the ends approaching their asymptote... a hung string would almost never assume a tractrix curve.

Forgive my ignorance, but what is a "SS" ?

SS is spreadsheet.

attachment is an extract from Dinsdale.

Tractrix is the involute of the catenary

dave

 

[WithTarragon]

Just so none of the readers get confused by this discussion ot tractrix...

Tractrix is NOT the shape or the contour of the horn or its sides or its profile.

The term tractrix (or exponential etc) refer to the rate of the expansion of the horn's cross-sectional area. It is very difficult to visually inspect a horn and guess its rate of expansion.

 

[Cassiel]

I'd like to DIY this. Maybe somebody has plans for something similar?

Blog | Specimen Products - Part 2

 

[Pano]

Do you need the profile plans for the curved throat? That looks like the hard part. The rest is simple, in concept. Getting it that clean would take some skill.

 

[Cassiel]

Do you need the profile plans for the curved throat? .

Yes.

 

[moray james]

are you sure?

A tractrix is the shape defined by a hanging rope, chain. Fix one end, and have the other end moveable, and be able to vary the length. TO my mind, easier to well define in a SS thou.

dave

I thought a chain or a rope suspended made a Catenary? Best regards Moray James.

PS: figured I should check. https://en.wikipedia.org/wiki/Catenary

PPS: here is a picture of my fancy paper Karlson K-Tube two inch id six inches long on an EV DH1A stupid simple amazingly fine sound.

 

[freddi]

paper is a good and super-quick way to sample a Karlson open end waveguide tube - I've used K-tubes for well over a decade and for the most part as long as used in an appropriate range, prefer the tubes over a CD waveguide or horn.

 

[picowallspeaker]

Yes.

But that's an exp vent BR; it isn't even a BLH !
BTW exp vent BR can be very good
PS I like acronyms

Ps2 The second photo shows the pieces hanging on the rope: that could be a start.
Just enlarge them and adjust perspective to obtain a workable 2D model

 

[freddi]

- tell me how to make strong mache with dryer-lint - then I'll be able to make some buddies for my vulture/shela-na-gig friend - also it could be useful for non-resonant K-tubes

An externally hosted image should be here but it was not working when we last tested it.

 

[Cassiel]

But that's an exp vent BR; it isn't even a BLH !
BTW exp vent BR can be very good
PS I like acronyms

Ps2 The second photo shows the pieces hanging on the rope: that could be a start.
Just enlarge them and adjust perspective to obtain a workable 2D model

Yeah that could be a start, a bad start. Mistakes are cheap though. We'll see.