Round horns opinions

[Arash]

actually I built a lathe to turn horn out of MDF or natural wood but the project turned out to me something more sinister than that! once I could turn a 30cm horn, I started thinking "why not build bigger ones!" and then the problem came up. the bigger means less stability of the MDF slices on the turner so I have to use two bearings with a shaft passed all the way through the MDFs. doing so means there is no way for shave the inner side of the horn into the MDF. I can only shape the outer side. it mean a negative mold of the horn. something like this:






then to used it to make a positive mold into the concrete and then di casting some molten iron into it. then using it as a strong mold to shape aluminum stack. but aluminum rings! although I felt I was really good to doing this in the middle of a 3rd world country, due to the freaking ringing of the horn, result was unsatisfactory. project canceled!

here is the aluminum horn I built, setting on top of my CS:




recently I ran into something which made me think again. project compromised! now I can build horns much much easier that before, as accurate as Avantgarde Acoustics build with multi-million dollar equipment. Iran's biggest Automobile factory has that equipment and I could find a friend kind enough to help me build the shape I want using ABS, PVC,...
I calculate Tractric horns and then export the ark into CAD and then cut it on a plexigalss **** using laser router. this would be the guide. then I shape the MDF using it. the accuracy is something about 1mm or less when I use some linear bearing to control the razor in x and y axis.
I know B-D O R I S horns are among the best sounding horns available. now I want opinions about the horn profile. does anyone know if Oris has any difference with Tractrix horns? any other idea would be welcome


this is the way the manufacturers build horns! nice and easy. as cheap as building a plastic flowerpot!

(this video is from youtube, someone makes replica of Oris 150 horns. I use a device like this but with a bigger mold area)

Edited April 22, 2014 by Arash

[JL Sargent]

I have a pair of the Jabo horns available on Ebay. They are made of fiberglass I believe and have a gelcoat finish. You might consider that method of construction. They seem to be tough too as I dropped one and no damage occurred.

[Schu]

3D printing... rapid prototyping allows for many design changes with very short lead times and more importantly, very precise repeatability using a variety of raw materials.

[Arash]

3D printing... rapid prototyping allows for many design changes with very short lead times and more importantly, very precise repeatability using a variety of raw materials.

thanks for the tip but I've thought bout it before. they are good but expensive and there are limited in sizes. I was looking for a practical method.

I have a pair of the Jabo horns available on Ebay. They are made of fiberglass I believe and have a gelcoat finish. You might consider that method of construction. They seem to be tough too as I dropped one and no damage occurred.

Fiberglas is also good but thermoforming (vacuum) is much easier and repeatable with least tolerance

dude, I'm not looking for the tip which way to go! I've found the way. I build molds with mdf and put it under a vacuum forming machine. what I'm looking for is opinions about horns profile. rightnow I'm working on Tractrix but some say good things about Oris horns. I want opinions about it. any info about it?

[seti]

Very nice work.... WOW!

[Arash]

the 8" 140hz Tractrix I calculated is about 78cm in diameter and 42cm in depth from throat to mouth. I don't know what is Oris 150 geometry but as Bert stated they are 78cm in diameter. I don't know about the depth. but Bert says they are fs150hz but my 150hz calculation turns out to be a 72cm of diameter and 35cm of depth. I think his horn is also a 140hz, he just wanted 10hz of margin or something. any idea?

Edited April 23, 2014 by Arash

[ClaudeJ1]

the 8" 140hz Tractrix I calculated is about 78cm in diameter and 42cm in depth from throat to mouth. I don't know what is Oris 150 geometry but as Bert stated they are 78cm in diameter. I don't know about the depth. but Bert says they are fs150hz but my 150hz calculation turns out to be a 72cm of diameter and 35cm of depth. I think his horn is also a 140hz, he just wanted 10hz of margin or something. any idea?

I remember Bruce Edgar saying his 300 Hz. Tractrix horns didn't "turn on" until 400 Hz. This "approximabe plus 33%" factor has appeared elsewhere. I just heard the best horn system I've ever heard at a public show/demo at Axpona in Chicago. Talking to George, the designer, he says his horns are Tractrix. GREAT imaging., best ever for horns, but it's the first round one's I've ever experienced, so don't take that is an absolute, just an opinion from a guy who has lived with lots and lots of rectangular horns for decades.

http://sadurniacoustics.com/horns.html

Edited April 30, 2014 by ClaudeJ1

[minermark]

Why not obtain an Oris horn and take it from there ?

When I start building them, they will be fiberglass.

[mustang guy]

I've seen people make bowls from old LP's. I wonder if a fella could make a round horn from one?