spherical enclosure

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#21
Hi

A 10mm thick 300mm sphere only weighs 3.9kg

in "Lightwieight concrete!" You can also get a

woodturner to do something like this 300mm sphere

(pic)in this case in Paulownia but others in Oz might

have it done in Jarrah or another hard wood of your

choice elsewhere on the planet. You could work in

plastic resin but would have to have someway of it

not sticking to a mold such as the Historystone molds

mentioned above.


AnthonyPT
 

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#22
Anthony,

it looks like that wooden sphere is made out of different ringed sections, just what i like to do..

I'm in the process of choosing a driver.
would this be a good choice?

I would like to combine it with a Hypex DS 1.2

i would like it to be a sealed enclosure.

many thanks
 
#25
Hi

AS I said earlier I would be inclined

to use two of the spheres that are not so big.

They would couple better with those Orb

spheres as they are fairly small.

Hence maybe a pair of the Tang Band W6-1139sc (PE 264-832)

in manageable spheres of 300-400mm. Note that

the magnet structure is not so heavy

and may not need so much counter weight or care mounting

Electronic crossover at 150hz or 200hz to the

Orb spheres, lots of 2 way electronic crossover kits

around or a DSP based system to make it future proof.

Seal boxes may allow some bass eq to extend things a bit

Jaycar has a kit KA-1814 for that sort of thing and no doubt

others do too. Altronics in Oz have kit K5561 and ESP site has

stuff on ELF type sub systems. Then with a suitable stereo amp

set up say with say 4 chip amps, (See Chipamp Forum for ideas) ;

you will get the most out of the Orbs coupled to you new sub

spheres. 🙂-))

Look at the pic on the 24inch Kris Metaverso NHT sub. that sort

of support avoids any problems with the sphere sliding around


http://www.partsexpress.com/pe/showdetl.cfm?&DID=7&Partnumber=264-832
 
#26
Hi Anthony,

thanks for Your feedback, but 2 subs is not an option
(the wife told me so..)
so I will have to do with one.

I also want to use a modular amplifier, I just finished building a 8 channel amp for driving the orb's, I don't feel like building another one..

the guys over at orb audio guaranteed me that the orbs go down to 80 Hz.


so I would like a single sub around 45 cm in diameter (still depends on driver specs etc..)

thanks
 
#27
Hi

Maybe if you have S.A.F., Spousal

Approval Factor to deal with just buy the

original Orb sub and then plan on replacing

the cabinet by a spherical one of similar volume

and if ported use or copy the port. A less than 5 inch

sphere with a 3inch or less driver might still be

giving you some output but I doubt that the Orbs

IMHO are 80hz-18khz plus minus 3db without the sub

being crossed over "a bit" higher than that. Look at all

the three inch Tang Bands and others, they seem to have a

100hz Free air resonance or higher, what does that

say to you?? While I have seen praise for the Gallo

spheres in many publications, I have never seen

a Clio or other measured readout of the

performance of those spheres. Has anyone else??

The Orb Sub is about 28 litres or less. 1/4inch

thick maybe? a Sphere 15.4in and 1/4in (390x6.5mm)

will give about the same volume. Its up to you.

Maybe 450mm with better stuffing might be the go!

See what is inside the Orb sub! Find yourself a

real good wood turner such as at a tech college, I did !

Regards

AnthonyPT
 
#28
Hi Anthony,

the ORB sub is too expensive to ship to Europe, that's why I'm heading in the DIY direction..

I've been busy with winisd and I found that a sealed enclosure will not work, so now it is vented, the (outer)diameter will need to be 48cm, the -3db point is then 41Hz

for my needs this should be fine i think..

I start working on 2cm MDF with a router to make the circles

one question..
is it OK to place the vent at the bottom? I really like the look of the white visaton driver..
 
#30
Hi

Not a great fan of ported designs

although I do have two 6th order bandpass

isobaric cylinders that go from 30-70 hz only! I

quite like the ELF ideas that Rod Elliot has on this site.

http://sound.westhost.com/project48.htm

The Elf design does give you deep bass with the right

woofer. At the moment I have an 88 litre box with

4 200mm Heppner doped drivers firing at the floor

and with a little EQ work it seems to suit my needs

until I finish making some u frame or Ripold open subs.

Would like to try some aperiod subs some day ! You still have

to crossover to those little Orbs and as I have said you may

need to measure them once they are run in to see how low

you can cross over to your new sub. If you can use a

turning lathe I saw a guy who made circles very easy using

an articulated bracket with the chisel on the end.

I enclose a picture of the isobaric bandpass 4ohm speaker.

AnthonyPT
 

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#31
Hi,

I was having trouble with the vents, (they needed to be longer than the sphere..), headed back to a sealed enclosure
so I tried with different drivers, now using a Visaton TIW 200
I have -3db around 42 Hz, still fine for me.. Volume needs to be 35liters, wich is much better..

the signal of the subwoofer is coming from a Home Theater PC with a M-audio revolution card, this card has Bass management and an LFE boost function (I hope this is about the same as descibed by Rod Elliot) so maybe I can boos the lower freq some more..

(and I'm using visaton because this is about the only one that is easy to get over here)

thanks
 
#33
Now I'm going to go buy a $.99 beach ball and glass the hell out of it!! This will be one of the cheapest enclosures I've built in a long time. I was also thinking about a half elipse, with two enclosed subs facing inward. Then there would be a horn setup, but I don't have the time to calculate everything. I think these look spherical subs look pretty sweet. As far as wood construction goes I'd say you'll be doing a lot of sanding to get the box to look right, but it's worth all the effort.
 
#34
I had a talk to my father about this (he is a sculptist for hobby)
and told me to go the polyester way.

so we (he want's to help me on this) are also going to buy a beach ball .

driver is ordered, still deciding on the amp.. and how to integrate it in the ball..

thanks
 
#36
Golden box ratio - Important or not?

How much will the "golden box ratio" change the sound of a sub as opposed to a standard cube with good internal bracing. The concept behind the golden box ratio is to reduce equi-distant walls to reduce resonance/standing wave frequency. But does this really play a role in subwoofer design?

I'd much rather do a cube as I could have much better internal bracing and the option of having it down firing at the same time.


Also, down firing vs front firing? Is the only benefit of down firing that you don't see the drivers. And is there any accoustical downfall of down firing subwoofers?

Thanks
 
#37
Re: Golden box ratio - Important or not?

Ornlu said:
How much will the "golden box ratio" change the sound of a sub as opposed to a standard cube
Click to expand...

Given the frequencies involved it should make no difference (in theory -- i haven't found it a problem in practise either)

Also, down firing vs front firing?
Click to expand...

Downfiring you have to worry about suspension sag.

And in my woofers a downfiring one would mean an upfiring one too (push-push)... not really practical.

dave
 
#40
just a small update to let you know that I started working on the enclosure..

instead of a beachball (they are never perfecetly round) i bought a styrofoam ball in a local hobby store.

the mold is finished, and sealed using a resin (recommended by the polyester shop guy)

i hope to lay the first layer of glass onto it tonight..
 
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