Foam Core Board Speaker Enclosures?

[planet10]

Originally Posted by KyleinCowichan

What size drivers are those meant for Dave?

It was a design exploration. It could be scaled to ant size. At the time (2008) the FE126/127e were dominating our work.

The design spark came out of reading a book on the Fibonacci sequence and that a set of inscribed Pentagons could be used to create a fibonacci spiral.

It can be made longer or shorter by adding more pentagons,

I can put this on a grid (if i can find the original drawing) or create a set of cartesian coordinates. It can likely be very easily descibed in a radial coordinate system (not by me, by someone that remebers their math)

dave

[Cal Weldon]

Originally Posted by planet10

We could call the Circular version<snip> "The Puck"

Have your lawyers call mine.

In the meantime, do something with the Pentagon, that does something for me. Not sure why...

[Don Hills]

Originally Posted by Cal Weldon

Without stuffing, it sounds bloody awful. With too much, it sounds like a regular FR in a box. Get it just right and something begins to get all fuzzy in your insides.

You're supposed to stuff the box, not yourself.

[planet10]

something with the Pentagon, that does something for me. Not sure why...

[klampykixx]

im yet to draw it up to see how much space it takes up, but i have this vision of one wide, tall but not deep(front to back) sorta like my little laptop horn but stood up, with two 8inch drivers, one on each side, and the four little 2.5inch drivers from my first horn directly above the 8's, with a tweeter on top of it all. having the mouth of the horn firing straight up the wall.

here is my plot on Hornresp. its simmed using an 8inch papercone driver from Jaycar. $40 a piece. i have a pair of "tornado" drivers that physically look very similar, but i will only use them to test the horn, then buy the drivers it was designed for if it sounds good.

the grey line on the plot is a single SS15 sub running on 1w as a comparison for frequency response.



what do you all think? am i heading the right direction?

also, this could very possibly get built using foam core. if not, ill have to take it away

[xrk971]

Originally Posted by planet10

It was a design exploration. It could be scaled to ant size. At the time (2008) the FE126/127e were dominating our work.

The design spark came out of reading a book on the Fibonacci sequence and that a set of inscribed Pentagons could be used to create a fibonacci spiral.

It can be made longer or shorter by adding more pentagons,

I can put this on a grid (if i can find the original drawing) or create a set of cartesian coordinates. It can likely be very easily descibed in a radial coordinate system (not by me, by someone that remebers their math)

dave

I have been looking at making a Fibonacci horn too, and did not know you could achieve it using pentagons. Usually, squares are used with a recursive progression of adding two successive integers to get the next number: 1+1=2, 2+1=3,3+2=5,5+3=8,8+5=13, and so on to get 1,1,3,5,8,13,21,... There is actually a triple Fibonacci spiral someone suggested for a water pump turbine on the internet. It would also make a good 'Puck' (tm) Cal, I think you might have a hard time trademarking such a common word that is so ubiquitous....

[xrk971]

Originally Posted by Cal Weldon

My idea is more of a daisy. Too hard for me to actually plot though. I hope you like rum style drawings.

I like the daisy. Flowers usually have at least five petals, good thing for you as you have a thing for pentagrams

Seriously though, this would work and you can actually make the exterior to resemble a flower with petal extensions for the horn mouths. This would have very high WAF.

[xrk971]

Originally Posted by klampykixx

im yet to draw it up to see how much space it takes up, but i have this vision of one wide, tall but not deep(front to back) sorta like my little laptop horn but stood up, with two 8inch drivers, one on each side, and the four little 2.5inch drivers from my first horn directly above the 8's, with a tweeter on top of it all. having the mouth of the horn firing straight up the wall.

here is my plot on Hornresp. its simmed using an 8inch papercone driver from Jaycar. $40 a piece. i have a pair of "tornado" drivers that physically look very similar, but i will only use them to test the horn, then buy the drivers it was designed for if it sounds good.

the grey line on the plot is a single SS15 sub running on 1w as a comparison for frequency response.



what do you all think? am i heading the right direction?

also, this could very possibly get built using foam core. if not, ill have to take it away

Klampy,
Looks like you are getting pretty handy with hornresp. Neat idea, you and Melotheory ought to get together - he likes big wall blow your face off speaker installations. My only comment is that with an 8 in driver, you should be able to get down to 40 Hz, maybe tweak the tuning length of horn? Looks like fun....

[surface tension]

Yes, I have sound! Delivery was a little slow on the drivers this time. Then I got hung up on the dreary details of earning a living...

Anyway, I built the second spiral in just a little over an hour and a half. I used 2.5" strips because my aluminum straight edge is exactly 2.5" wide, made cutting the strips go really fast (I know, very scientific!). As someone much earlier in the thread suggested I creased the strips down on the sharp edge of a kitchen countertop. I ended up with fairly regular crease marks on the strips, then I wound the strip up tightly into a spiral coil. Hot melted the strips in place and ran a bead of Titebond II all the way round the edges to seal. Used a bit of coat hanger wire to punch a hole through the spirals for the wire. Mounted a piece of scrap 3/4" Sonic Barrier directly behind the driver and lightly stuffed the inner spiral. I think mounting the driver properly was the big challenge. I ended up taking some shortcuts on the first model that I think limits the performance (I was in a hurry for a test listen). I used small screws and nuts with a matte board backing strip. Oh, and I used Dollar Tree foam for the top with Gorilla Glue (messy, but effective).

The sound- Well, at first it sounded thin with very little bass. So I pulled apart an old pillow and started stuffing the daylights out of each outer opening. It took about half of a normal size pillow stuffing material to adequately fill. Wow! The bass really tightened up. That little Vifa driver is pretty amazing, needs no tweeter, nice midrange. I have to agree with what has been said before about the amount of stuffing used is very important to the final sound. So I'm just running it mono for now until I have some more time to finish the second model. Can't wait to hear in stereo. Even in mono it has a room filling capability. In short- this is amazing! I keep looking at that little driver in disbelief while listening. Hard to believe that such a small driver can produce that much beautiful music. Stand up bass sounds fantastic! I'll be finishing these off now that I've heard what it can do. Right now the plan is to use a more rigid material for the top to ease driver mounting and aesthetics. I need to get a new router bit and glue to finish the second model, maybe this weekend.

I have some other foamcore ideas that I want to try out when I get these done. Thanks for putting this project out there. It's a keeper.

[xrk971]

Originally Posted by surface tension

Thanks for putting this project out there. It's a keeper.

Surface Tension,
Awesome! Congratulations! I am still very impressed by how fast you build these - I don't think that most of us can compete with your foam core dexterity and skills.
That now makes three people with completed horns - and three people who agree that the sound is amazing. And I am glad that you agree that the baby Vifa TC9FD kicks butt - pretty amazing driver for less than $12 isn't it? Thanks for the feedback and tips that you are using in your build. The idea of stuffing the horns from the outside in is different than what Cal and I did - and it sounds like you stuffed it much more and much tighter along the length of the horns? Did you score the inside of the spirals before running it over the edge of the counter? That makes it bend much easier. When you hear it in stereo, the effect is not 2X but more like 10X more impressive. Be prepared to be blown away.
Regards,
Xrk971