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

[perceval]

Funnily again, I was going to write that the only two full range drivers available here from Fostex are the FE126EN and the FE83EN.

 

[Cal Weldon]

Hey perceval,

Looks like you drew a grid on the foam and then traced it? I found it easier to overlay the foam with the paper and poke holes through it. Remove the paper and trace the holes into spirals. Blaides has an even easier way with the tracing wheel.

 

[perceval]

Yep, I'll use your method when I come around to do the real things.

Unfortunately, in my case, wife was not too impressed. In fact, she said "what is that ugly box?"

Hmm... will try to turn them into some kind of art, like the printed ones I saw, or maybe even painted.

 

[Cal Weldon]

wife was not too impressed.

Well you tell her, were not to impressed with her either. Doesn't she know a work of art when she sees it?

Sheesh!

 

[gmonno]

Giuseppe,
You are one of the lucky ones who has such a nice driver. The Eikona's are very special drivers that deserve a special Cornu. If you want to fully utilize the Eikona's capabilities, I recommend an extra large but thin Cornu that is 34 in x 4 in deep - that will give deep bass extension down to mid 40 Hz while keeping the sound balanced. Because of the large size, I recommend you make the front and back out of thin 5 mm plywood and use foam core for just the channels so that they can be curved and glued. Use stuffing in the main driver chamber and loosely stuffed in the horn channels leading from the throat to the bifurcation point. Put the stuffing in a porous cheesecloth "sock" with a string tied to it on both ends so you can pull it out to adjust amount of stuffing inside the sock, and pull it back into position.

Here are the results of the simulation for SPL vs Freq, Impedance, Cone Excursion.

It is important to mount it on a wall at the correct optimal height of 45 inches from the floor (adjust to taste but start there).

Good luck!

Cheers,
X

Thousand Thanks, XRK971, your words help me a lot.
34 inch is a little big for the wall they are intended to stay, but think will do something between 30 and 34 inch.

And thanks for the plywood suggestion.

Now I nedd to identify where to buy the foam.
Is there any code os something to search?

Lots of thanks again

 

[Cal Weldon]

I have Googled Foam Core Madrid but came up with nothing. Do you have dollar stores there that might have cheap arts and crafts type items?

 

[gmonno]

I have Googled Foam Core Madrid but came up with nothing. Do you have dollar stores there that might have cheap arts and crafts type items?

Cal, a question that sure has been already answered : is there a reason to use foam apart from weight?

I mean, I could do the spiral with plywood, is there reason why not?
More difficult?
More weight?
Some impact on sound?


Many thanks

 

[Cal Weldon]

If you have the skills, then wood is preferred. For most of us, it's out of reach or would take so long as to remove the fun factor.

 

[xrk971]

You might try flexible or "bendy" plywood. Here is an example and it looks like they may have distributors in Europe.

KoskiFlex - Thin and flexible birch plywood | Koskisen Oy

Koskisen Spain and Portugal

Calle Eras, 20, Planta Baja, Local 2
28411, Moralzarzal (Madrid)
Spain
firstname.lastname@koskisen.com

There is a foam board distributor in Germany: http://www.crescent-europe.com/Produkt%20Listing%20Kategorie/navi-produkte/subnavi-produkte/treeevent-5/5.html

 

[xrk971]

Thousand Thanks, XRK971, your words help me a lot.
34 inch is a little big for the wall they are intended to stay, but think will do something between 30 and 34 inch.

And thanks for the plywood suggestion.

Now I nedd to identify where to buy the foam.
Is there any code os something to search?

Lots of thanks again

Let me know what your max size is? 30 inches?

 

[Dave R]

Unfortunately, in my case, wife was not too impressed. In fact, she said "what is that ugly box?"

Hmm... will try to turn them into some kind of art, like the printed ones I saw, or maybe even painted.

Idea: use some art work created by kids or grandchildren (as the case may be). That sentimental value might help promote the musical art.

 

[gmonno]

Let me know what your max size is? 30 inches?

Yes, 30 inches would be max size, as the wall has 90 inch length


As for the foam, what about using CORK?
Has anyone tried it?

And I've found foam here in Madrid, there are places were to buy depron


Thanks

 

[gmonno]

You might try flexible or "bendy" plywood. Here is an example and it looks like they may have distributors in Europe.

KoskiFlex - Thin and flexible birch plywood | Koskisen Oy

Koskisen Spain and Portugal

Calle Eras, 20, Planta Baja, Local 2
28411, Moralzarzal (Madrid)
Spain
firstname.lastname@koskisen.com

There is a foam board distributor in Germany: Crescent Europe - Best of Passepartouts

This would be fantastic, and they are near Madrid, only 20Km far.
I'll call them tomorrow, hope will not be obliged to buy a 100m roll.

Many thanks

 

[xrk971]

Yes, 30 inches would be max size, as the wall has 90 inch length


As for the foam, what about using CORK?
Has anyone tried it?

And I've found foam here in Madrid, there are places were to buy depron


Thanks

Just make it 30 in x 30 in x 4 in deep - should work fine - 52 Hz reach (-3dB point). Cork is too soft and flimsy to make a rigid channel wall.

 

[Squiffything]

Not sure if this will work and it's only an iPhone vid but here's a taster of mine

https://www.youtube.com/watch?v=uE1f1JGO2YE

Enjoy, I am

 

[xrk971]

Squiffy,
Thanks for posting the video! iPhone video probably doesn't do it justice. Looks very nice and glad you are enjoying it.

 

[Squiffything]

Squiffy,
Thanks for posting the video! iPhone video probably doesn't do it justice. Looks very nice and glad you are enjoying it.

The iPhone just doesn't do them justice.

X I am currently sitting with the dog chillaxing to the sound of Griegs Peer Gynt Suites and Piano Concerto and the sounds filling the room is just blowing me away! The bass is rumbling my feet yet every tiny little note including the tings on the triangle is perfectly clear. I can almost hear the swish of the conductors baton it's so defined. These puppies are definitely made for classical music without doubt.

 

[Turbon]

Hi gmonno.

Se if anyone near you sell "kapa" boards. A company in Holland makes these.

Regards

 

[Squiffything]

Last post tonight and just wanted to say Muddy Waters runs deep and clear on the Cornu's

Wow the blues are sweet. I cannot believe a home made turntable and a set of nothing drivers in a packing case could produce such fantastic sounds.

Now where did that post about the tall horns out of foam board go

 

[xrk971]

The magic starts all over again for a new Cornu initiate.