Patents on horn profiles?

[MaximumPuffer]

Just wondering if anybody knows of any patents on particular horn profiles such as Tractrix, Exponential, Conical etc... I've searched google quite a bit and cant find anything concrete.

THX

[Jmmlc]

Hello,

In October 5, 1927 P.G.A. Voight got the British patent 278,078 for a horn based on the tractrix curve (this horn is then called "tractrix horn")

ref:
http://www.sonicdesign.se/horncalc.html

you'll find reference to several horns patents at the bottom of the page:
http://en.wikipedia.org/wiki/Horn_loudspeaker

Best regards from Paris, France

Jean-Michel Le Cléac'h

[MaximumPuffer]

I guesss what I am asking is if these patents are still pending because i see quite a few manufactures making all different types of horns. I imagine that every geometry at some point held a patent, but how many of these still apply today?

[Geek]

"For every dollar a patent makes you, it costs three to defend it" - NCO Lawyer as they got their butt kicked by Novell

Many companies have neither the budget or belly to defend their patents. THAT is why you'll see so many knockoffs.

Cheers!

[MaximumPuffer]

hrmm interesting

[Overkill Audio]

Hi Max,

Here is a good example of the validity of a typical loudspeaker "designers" patent claims. Check out Tim’s "patented" front loaded horn at www.fergusonhill.co.uk .
Obviously he was not aware of the last 80 years of prior art....

It’s actually amusing and a bit sad at the same time that in audio everyone from Wilson Audio down to Ferguson-hill are allowed to claim ( and then state they have a granted patent, but never show the patent number...) to have invented and patented some radical new aspect of loudspeaker design when the truth is they KNOW they have not.
The problem is so endemic that nobody even challenges the false claims, even the "independent" audio journalists who are supposed to be experienced in audio matters let all the B.S. pass as if it is fact.
False marketing claims abound and one Journalist who has done his best to expose them is the ruthlessly honest Srajan at 6 moons who challenged the wild and blatantly false claims made by the B.S. King Albert Von Schweikert. Srajan proved his point and the Von Schweikert website was changed to tread just on the legal side of **, but still **!!

If only others would follow Srajan's lead audio in general would be a lot better off.

Cheers

Derek.

[Overkill Audio]

PS These are the two original 6moons articles.


http://www.6moons.com/industryfeatur...erphysics.html

http://www.6moons.com/industryfeatur...rphysics2.html

[Timothy Hill]

Hi Derek,
I just came across your post on Diy Audio,
I am actually very aware of the last 80 years of prior art in the field of Horn Loudspeakers. I am a great fan of horn loading for Loudspeakers in all it's many forms.
Our horn loudspeaker patents are not pending but fully granted. Our UK Patent registration Number is 3007086, and I can provide details of all our European and North American patents if you would like.
I guess the main details of our patent concern what I calculated would be an ideal horn shape that gives an even sound wave expansion on a front loaded horn from a circular throat to an oval mouth ! that and the fact that it is made of clear cast acrylic.
We did much research at Loughborough University with laser interferometry and sound wave flow measurement across the frequency range etc to develop this horn profile.
You have to remember that many small companies such as HiFi manufacturers are keen to protect their original ideas. you only have to look at companies like Dyson, who's Cyclone ideas were copied by other big manufacturers, and it was the patent that allowed them to go through the courts and receive judgement in their favour / and a considerable recompense.
Anyway it's good to see lots of discussion on horn loading for loudspeakers on forums such as this.
Kind regards
Timothy Hill
c/o Ferguson Hill Studios.

[gedlee]

Originally Posted by Timothy Hill

Hi Derek,
... the main details of our patent concern what I calculated would be an ideal horn shape that gives an even sound wave expansion on a front loaded horn from a circular throat to an oval mouth ! that and the fact that it is made of clear cast acrylic.

I'm guessing that the "clear cast acrylic" part is the most significant aspect of the claims. That's because a horn or "waveguide" with the features that you discuss is not very new, easily shown to be an obvious derivative of the prior art and even shown in the prior art. But a certain shape AND cast in acrylic, that might be new. Just cast it in polyurethane and away you go.

To the original question, most contours are quite old and hence even if they were patented would have expired by now. I trued to patent some contours but in the end I found that it just wasn't possible to get anything reasonable since just a small change makes a now contour. The classic example is the Peavy "Quadratic throat ..." . Its an almost rivial change from an Oblate Spheriodal contour, but it got a patent. Thing is that this patent is also trivially easy to avoid thats its totally useless. Patents, for the most part are marketing tools. Unless you are big company like Bose, you don't have much chance enforcing them.