Ever think of building a Cornu Spiral horn? Now you can!

[Jim Shearer]

I have been experimenting with different types of music on the FE108eS Cornu horns. If mine sound anything like the commercial product, then I heartily agree with the review that called them highly colored. But for some material, like solo guitar, they are simple magic: jaw dropping, holographic presentation. Listening to Sharon Isben, Jason Vieaux and John Williams is a you are there experience.

Female vocals and solo violin are similar.

Building the Cornus has been a lot of fun, even if I don't want to keep them around.

Cheers, Jim

[xrk971]

Jim Shearer,
I know what you mean about the magical sound for certain material. Female vocals, and jazz with horns or guitars really shine with the cornu. This is what made me want to get the word out to everyone about these cabinets. Nice to hear that your set worked well. As you can see, installing them on a proper wall really makes a difference. Holographic you are there describes it right on
Thanks for sharing.
X

[Cal Weldon]

Originally Posted by xrk971

The E60 is a nice driver, I think Cal may have tried it.

I actually have the Jordan J6T. Didn't have much luck with it.

Originally Posted by Jim Shearer

highly colored.

I like to think of it more as UFA [uncontrolled frequency augmentation]

But for some material, like solo guitar, they are simple magic: jaw dropping, holographic presentation.

So true. I am also amazed by the way those cabinets give the impression of a larger driver.

Building the Cornus has been a lot of fun, even if I don't want to keep them around.

Yup, mine were delivered to the speaker warehouse just this morning...
...now what to build next?

[jsouder]

Been working up designs for the 1" Tang Band FR speakers in an 8" Cornu. Thought I'd try the 6 Horn design, but couldn't get the dividers to work because the tolerances were too close. Reverted to the 4-horn spiral. Using a fiber gasket material, 1/32" thick, that I got from an auto supply store. Cuts easily, and is rigid in compression. It came rolled, but I cut 1" x 26" widths and left tightly rolled over night. Took the .pdfs scaled to 8" and used spray adhesive to attach the print to the back of commercial grade floor tiles (cut to size on a table saw). Gluing the spirals went pretty fast; for the ends where they run straight along the sides I cut pieces of tile to fit. To stick the top on I put a thick coat of spray adhesive on the back plate, threaded the wires through while standing everything on an edge, then clamped together using some 1/8" plywood for backing. Before gluing I stuffed some wool behind the drivers.

Looks O.K., sounds horrible with cutting in and out. The wires on the speakers are so fine it's hard to get them attached well (even with soldering). Will do some troubleshooting, but the wife just walked in and turned the amp off saying she couldn't take it anymore. Well, that's development: win some, lose others!

[xrk971]

Jsouder,
Wow, floor tiles and gasket material! You really are trying some neat alternatives there. Does it sound bad due to loose wires or is sound bad? Prezden made a small one for a 1 inch driver with some success but I think it may have been bigger. Very cool, and glad you are thinking out of the box! Thanks for sharing.

X

[solhaga]

jsouder, great idea with the gasket material. 1/32" that´s only 0,8 mm, right?
Isn´t it hard to get the whole box rigid enough?
Perhaps it is if it is only 1" deep though.

I´m using floor dampener, 5 mm thick XPS foam.

The initial horn is then a little bit harder to get correct:

Perhaps the gasket material could be used in the beginning for flexibility and then have foam for rigidity.


Doing some workout:


Hopefully I will be able to measure these tonight:

[prezden]

jsouder- sad to hear they didn't work out for you
The ones I made were the same size. They turned out really well. The sound is much more that one would ever expect from a 1" driver. I wonder is the gasket material didn't seal up well enough. Some kinds of plastics are a bugger to glue.

cheers

[xrk971]

Prezden has a good point about making a good seal with plastic channels. That is one nice thing with foam core is that it bonds really well and is dimensionally stable and rigid vertically. A small pinhole leak and the sound wave collapses - end result is no bass amplification.

[BWRX]

Some of you guys mentioned that one issue with the spiral horns relates to not filtering out the higher frequencies. This got me thinking about helmholtz resonators. It seems like you could add a helmholtz resonator (or band-stop filter) at the throat of the horn to help reject an unwanted frequency.

Taking the idea in another direction, you could add an expansion chamber between the driver airspace and the throat of the horn to create an acoustic lowpass filter.

Of course it seems like these could only potentially be accomplished with a 2 path horn in a square/rectangular shape.

[iko]

Originally Posted by jsouder

Looks O.K., sounds horrible with cutting in and out. The wires on the speakers are so fine it's hard to get them attached well (even with soldering). Will do some troubleshooting, but the wife just walked in and turned the amp off saying she couldn't take it anymore. Well, that's development: win some, lose others!

Awww... that's too bad, they're soooo cute those little things.