sphere speaker

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Laurens

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Joined 2012
#1
Good evening everyone,

I am new to this forum, and I thought let's enter with the project i've been working on lately.

I'm quite new to speaker building but after reading about filters, cabinet design etc. I thought let's give it a try!

Here's my idea: Working in a audio store in holland I got quite bored with the conventional square cabinets. Therefore the idea of a spherical speaker popped into my head.

Drivers used are the dayton nd105-8 and some tweeters I still have lying around. don't have any specs on them, but being a poor student I figured let's not spend any unnecessary money. Plus it's really budget being my first project.

Box is a sphere with +/- 23 cm diameter, sealed. The idea is to make it out of glassfibre.
Any thoughts about inertia and baffle step compensation are welcome. All thoughts are welcome actually.

Pics will come if wanted.

Hope to hear what you all think.
 
#3
Definitely share some pics! Sounds like a fun project.

In many ways, a sphere is an ideal shape for a speaker cabinet, as it more or less eliminates edge diffraction- obviously, maximizing this effect requires very careful driver mounting to really capitalize on it to the nth degree but either way, it should work "fine."

Eric
 
#5
The point of the sphere is to more or less eliminate diffraction, mounting speakers in such a way that the "rim" of the speaker isn't a relatively smooth transition to the sphere would be counterproductive to the "point" of making a speaker cabinet that shape.
 
#6
Laurens said:
Careful driver mounting in what way? And I wonder if the fibreglass will be strong enough.. Any thoughts on how to reduce vibrations?

Anyhow, here are the first pics: IMG_2141 | Flickr - Photo Sharing!
Click to expand...

The driver should be flush mounted as mdocod says, add stuffing (Rockwool, fibreglass, angelhair, sheepswool, tacke your pick) to reduce the single standing wave you will get with a spherical enclosure.
 
#8
@Mark.Clappers: Yes, i've been wanting to make a decorative edge following the curve of the sphere, over the screws. that would make it more or less flush mounted if i'm not mistaken.

@Studio Au: Yes, i've come across those a few times. Looks nice! The mounting area I have now(see pictures) is similar to what you've done with the bowls. Problem is that I already have the fibreglass and resin.. So i'm gonna stick with that..
 
#9
Hey all,
David Crewe from Chattanooga TN.
This is my first post on this board. Just thought these might fit the thread.
An externally hosted image should be here but it was not working when we last tested it.

http://s818.photobucket.com/albums/...action=view&current=G3-2-speaker_014_1-SM.jpg

I've been working on this design for about 4 yrs. I think it's starting to come together. They are all turned wood and not for the squimish. Hour eaters. The drivers are Seas ER18ex001 & ScanSpeak D3004-6020-10. More on the bucket Pictures by davidc549 - Photobucket

David
 
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#12
Well david, looking at your project it seems like i've got a long way to go 😉

A few questions. First off, does anyone have any experience with the dayton ND16FA-6?
I guess that for a mere €9,- you can't go wrong. 😉

And any ideas on how to mount the tweeter? I've been thinking of flush mounting it into the sphere above the woofer.. but then you'd get problems with the directivity i guess, since it will be pointing upwards.. And a plate following the mounting area of the woofer would be pointless.. the whole idea of not having to use any baffle step compensation would be gone then..

Btw, spheres have been fiberglassed and are drying. for those interested, pictures will come tomorrow.
 
#13
Oh man the possibilities are many. My thought would be to start off with a circular baffle just big enough for the tweeter and glass it into the sphere. You will be able to align the acoustic centers (depending on your philosophies on that subject) and keep the faces parallel. (Oops, just reread your post and saw were you didn’t want to do that but, it will yield the best results. As for the baffle step thing, as long as you radius the edges of the tweeter baffle you’ll be fine. The actual surface area will be virtually mute and any bumps that are realized will be directed mostly upwards and prove to be insignificant.) It could also be fun to try an MTM with all of the drivers flush mounted with the tweeter perpendicular to the floor and the woofers tilted up and down. Reflections may wreak havoc thogh. How about putting the woofer on top with the tweeter facing out for an omnidirectional “Pluto” type thingy.
Just a few suggestions that may spark something.
Good luck.
David
 
#14
Salami-Slice

Laurens said:
Good evening everyone,

I am new to this forum, and I thought let's enter with the project i've been working on lately.

I'm quite new to speaker building but after reading about filters, cabinet design etc. I thought let's give it a try!

Here's my idea: Working in a audio store in holland I got quite bored with the conventional square cabinets. Therefore the idea of a spherical speaker popped into my head.

Drivers used are the dayton nd105-8 and some tweeters I still have lying around. don't have any specs on them, but being a poor student I figured let's not spend any unnecessary money. Plus it's really budget being my first project.

Box is a sphere with +/- 23 cm diameter, sealed. The idea is to make it out of glassfibre.
Any thoughts about inertia and baffle step compensation are welcome. All thoughts are welcome actually.

Pics will come if wanted.

Hope to hear what you all think.
Click to expand...

Starting at the baffle board, you can salami-slice your design and build it up out of a sandwich of routed MDF panels. The last panel can be left flat; as doing so, will have absolutely no acoustical consequences so long as you reinforce it internally with ribs. Then, all you need to do is remove the steps, fill, and finish the exterior and mount the driver.

For drivers, you may want to consider coaxial designs made by BMS and others. Design for one of these, make your baffle board removable, so you can adapt it to the drivers you have on-hand as a first step.

Attached are the appropriate pages from Olson for you the study.

Regards,

WHG
 

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#18
@David: with your first idea of the circular tweeter baffle you mean to have a second baffle just for the tweeter? A bit like the EBTB Luna, but smaller. If that's what you mean.. It would be an idea indeed. just have to make sure the baffle surrounding the woofer(would like to make it out of one piece) follows the curve of the sphere right?

@whgeiger: the salami idea would probably be a more solid construction. Problem is, I already fiberglassed the spheres and woofer and tweeter have been bought.. so i'm more or less stuck with that 😉 Still, I'm surprised how strong and rigid the glassfiber is. 🙂

And the thing is, i already had a fullrange project and for this one I'd like to up the stakes a bit.
 
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