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

[sapdog]

Just got back from vacation and looking at what is on the shelf - I have a pair of tang band W4-657SB aluminum drivers available. From what I can dig up on specs they have SD of 0.0057m^2 - so this evening I may try to work out what geometry for the spirals would be appropriate. Looks like the driver is about 3" deep.

My alternative would be to pull some Radio Shack 40-1197's (Fostex FE103 wannabe's) out of an old pair of BD-pipes I built many years ago.

But first - off to the dollar store to pick up the foamcore.

 

[Cal Weldon]

It's up top in aisle 5, north end I think. No open box that I saw, just a full one.

 

[xrk971]

Sapdog,
For a W4 with 57 cm^2 Sd go with a 24 to 27 in Cornu that is 4 to 4.5 in deep.
Good luck.

 

[Benedetto]

The plans are posted as a pdf by Planet10 somewhere in this thread.

Hello everybody,
searched this thread but could not find this PDF by Planet.
Only findings are 2PDFs from China named cornu_orj and cornu_orj1.
Are theese reliable ?
Thxalot.

 

[xrk971]

Those work too. One is for a more curved smoother channel design, other is more like traditional squared corners design. Planet10's pdf is in the Foam Core thread before Cal broke the Cornu off on its own thread - post #230: http://www.diyaudio.com/forums/full-range/223313-foam-core-board-speaker-enclosures-23.html#post3266494

If Cal can put a link to it at the first post of this thread for easy finding in the future...

I will add it to the first post of the Foam Core thread for easy reference too.

 

[Benedetto]

Cool,
thanx again.
This is exactly what i was looking 4.

 

[gimebakmybulits]

Will there be a big difference in sound between the smooth spiral and the squared off corners?

 

[xrk971]

The smooth corners may let more HF leak out compared to square corners. Although folks like the sound from both so it may not make much of a difference. The ratio of the throat area vs the chamber volume probably has more impact on the high frequency cutoff.

 

[prezden]

Thanks xrk and cal- you guys are great.
I'm just starting work on a new pair of 24" cornu's. This will be pair number 4.

 

[xrk971]

Prez,,
I think you hold the record for most cornu's!
What driver are you using? W4 bamboos?

 

[Cal Weldon]

Pair #4?

Ya baby!

 

[prezden]

I will be using the bamboo w4's for these ones. They are really heavy so I'm going to laminate a piece of 1/8 plywood onto the foamcore to reinforce it. I'll let you know how it goes.

cheers

 

[prezden]

I messed up on my calculations for some new Cornu's
The boxes I built for the TB W4's are too small so I need to get some different drivers. Solen has 2 options- TB W3-1364 or SEAS FU10RB H1600-08. Either one would fit - one a little small and one a little large. Here are the specs for them. Your advice would be greatly appreciated.

 

[xrk971]

What size are the boxes?

 

[prezden]

Boxes are 22"x4.5" with a 24" front panel.

 

[merlin2069er]

Hey, cool concept. How about using a 3d printer to print out the spiral cone (and maybe piece it together)?

That might be possible.

 

[xrk971]

A 3d printer can certainly work but the material is very pricey for a large build like a 20 inch x 20 inch x 4 in deep speaker. It would cost only $4 to $5 in foam core.

 

[merlin2069er]

I guess. Some guys have started to extrude their own plastic. So, cost is a relative term.

See...

http://www.kickstarter.com/projects...robust-inexpensive-filament-extruder?ref=live

 

[prezden]

Boxes are 22"x4.5" with a 24" front panel.

No Suggestions

 

[Benedetto]

How about using a 3d printer to print out the spiral cone ?
That might be possible.

This is scary,
just chewed about it last week.
And dreamed about using some kind of wood-based
material...