I've searched the forum and can't find this topic covered before. I think most people have trouble finding space and need to make odd shaped boxes but I have no such problem.

What I want to know is what is the ideal shape for an enclosure?

I would think it would be round and dome-shaped at the back. What do you all think of that idea? Obviously it would be err, imposible to make out of MDF but you could make it hexagonal. (I'm a carpenter so I'm not going to start learning all about fibreglass)
Any opinions?


Doug

ideal shape? there is none. just dotn make it square. liek fi the box is really longand really shallow then this isnt as ideal.

how ever whats inside the box is air, air is thin and can move around quite freely even in complex shapes. the simpler the shape the better. but dotn make it square or u get reflections inside the box.

a sphere is the way to go. show us one when you're done.

A sphere hey, now thats interesting. I know not to make the box square. I read somewhere recently that high-end boxes are made with all sides on odd angles to avoid standing waves and I thought round might be even better. So what I suggested, (round and dome shaped at the back) is getting pretty much like a sphere.

(I have this type of brain that just dreams things up, like, a photographic imagination)

The other thing I dreamt-up in this ultimate sub box idea was the sides were lined with a thin rubbery coating with bumps all over it. Isn't there a type of paint they use in places where they want good accoustics? like theatres, where they don't want echoes?

Anyway I think the closest I'll get to it is to have all the corners filled with a pyramid shaped block of MDF or maybe have 5 sides.

Gee I'm making this difficult for myself

Thanks for the replies. I might take a few weekends on this project but I'll let you know how it went.


Doug

If you use a convential rectangle enclosure, you can do what I do and lay slices of PVC pipe in the corners to aid with the air flow.

The surface inside your enclosure, would that be like a golf ball, I know B&W use it on their HT woofers.

Slightly off-topic, but a few years ago a guitarist mate, some friends, and I went on a holiday to the Sunshine Coast.

This place we were staying had this room in the 'attic' - and it had the most incredible acoustics! There were no parallel walls at all, and the roof was angled relative to the floor. I'm not sure I'd want to live in it, but it made for some pretty amazing sounds jamming.

<<slices of PVC pipe in the corners >>
I'm with you. I know what you mean. Do you fill the corner between the pipe and box?
Golf ball Yeah something like that but more like those yellow practice cricket balls, that sort of soft texture as well as the bumps.

<<room in the 'attic' >> I don't think it's off topic at all, very interesting

I've been thinking about how I will tackle this and I think I'll go for a 5 sided "sphere" if you know what I mean. It will be rather complicated but see the picture, thats how I made spacer rings to fit my Focals into the doors. It's Rock Maple which is what Fender guitar necks are made of. I thought it would be better to use than MDF.

Well its ten o'clock and I'm knackered. I spent the afternoon and half the night in the shed. I spent hours working out what angles and shapes to cut this 'spherical' sub enclosure, experimenting with small pieces then I cut the first full sized piece and realised the design wasn't big enough to fit the sub in the front!

So then I made a wedge. It took 1 hour to cut out and about 2 hours to put together. (I already had the size and shape drawn out)

It doesn't fit

I am going to bed now

Doesn't anyone like my sense of humour?
Stuffing around in the shed for hours and hours and in the end - it doesn't fit - I mean it's just hilarious!

Well anyway a few days have passed and I've just made another wedge and this time IT FITS. This is just a temporary measure to get the damn thing going so Juls can check out my Boston and compare it with his JL.

The spherical enclosure is on the drawing board and is coming along. Finding the volume of a sphere was easy. There's a formula for it. But I need to calculate the volume of the section that will be "sliced off" to fit the sub in and I think you need calculus for that and I can't be bothered getting my old books out so I just did a bodgy calculation and I'll find out if I got the volume right once its finished by using sand or whatever.

Once again it's time to go to bed. What a life!

Here's a thread on diyaudio following the construction of a spherical enclosure using fibreglass:

http://www.diyaudio.com/forums/showthread....10&pagenumber=5

sounds liek your having a good time of it there doug. I think its alla bit too stressful
I do like your spacer for your focals tho looks good.

If your wanting a sphere then why not acrylic?
http://www.waterfountains.com/acrylic__spheres.htm

Get a laser or watercutting firm to cut/ shave the opening to suit the sub diameter, tap holes in the face and instant bling.
You can then see cone & basket at the same time

Thanks for those replies, they are some great ideas. I like the idea of being able to see the sub basket. Being what I am though I like to use the resources available in my back yard and take on the challenge. But if I think its getting too much I would certainly look into the alternatives you have put forward.

By the way the temporary wedge is done and the sub is in and going. I will have to take the box out to change my oil - but then that doesn't happen very often lol

I think a cone/shell would be the optimum - so no surface is directly behind the woofer, also the taper would disspate the back-wave.

An inflated beachball + FG ideal for sphere enclosures. Not easy to mount a woofer too, however

Doug also just to add:
another advantage to having a sphere shaped enclosure is mounting angles.
You can face / mount the sub at infinate angles thru' rotation until you find the optimum.
the more I think about it the more i'm likin this idea of yours!!!

Just wondering with a long and shallow enclosure, I'm making a 30L enclosure where the internal measurements are 35H x 65W x 13L and the baffle is angle so the sub is facing slightly upwards (its for a inverted type R)
What would the disadvantage of this ?

Inverted might be different but the "ideal shape" is to reduce standing waves - (sound reflecting off a flat surface back onto the cone and back again and again. I think thats right) But yours in on a slight angle? It should be okay

definatley lol, i think im inspired...maybe soon therell be a whole lotta CAAers with spherical sub boxes in their cars lol..

spherical

like that.....but id do it a little different...id have the sphere cut halfway, and have the sub on it.....or taking up a little bit more than that..if you get what i mean......what about a cone??????

Wow I didn't realise I was gonna start a revolution!