Low-cost Spherical Speaker Array

Acoustic instruments radiate sound in a wonderfully complex, 360 degree fashion, while conventional loudspeakers radiate in a much more boring, spotlight of sound. You could spend a ton of money on fancy products:

Hemisphere from Electrotap
Experimental Meyer Array

or you could follow these instructions to build a cheap array out of IKEA salad bowls and surplus automotive speakers. It won't sound as "accurate" as those other speakers, but it's surprisingly good and looks pretty cool on stage.

Special thanks and apologies to Dan Truman and the researchers at CNMAT, who's scientific work directly inspired this project.

P.S. Here's another cool loudspeaker array.

P.P.S The Stanford Laptop Orchestra built some nice ones here.

P.P.P.S. This one is nice, too .

Step 1: Acquire the Materials

The goal of this project was to be as cheap as possible. You'll want eight (8) loudspeakers. I would have used these speakers:

$5.50 speaker

but All Electronics was out of them. I got these, instead:

$7.50 speaker

The important considerations were an impedance of 8 ohms (which is normal for home stereo speakers) and good frequency range. (in this case 70-10k Hertz). Sound localization is more acute at higher frequencies, so response >1k Hertz is especially important. It would be better to add a sub-woofer to make up for thin bass, than to have no high end.

While at All Electronics, get some Speaker Terminals.

I used four (4) "quad"  terminals, but the four-pair ones look good.

(NB: If all electronics doesn't have these anymore. Try Parts Express or Radio Shack)

The other major elements in this project are the bowls. They cost $5 at IKEA:

Reda Bowls

Insanely cheap. Get two (2) sets because you need two of the biggest bowl. They also come in white. I imagined using one of each color, so this project would look like a big fishing float. Ultimately, though, solid red seemed best.

UPDATE: These bowls are no longer sold by IKEA.  Sorry.  

Finally, the miscellaneous hardware. 8 speakers x 4 mounting holes = 32. My local Ace hardware provided 32 machine bolts, locking nuts, and washers. Also, pick up 8 small nuts and bolts for the terminals. Most of the speakers were fine with 1/2" bolts, but the top and bottom ones needed longer (1 1/2") ones, as you'll see later. This may vary, if your parts are different.

Also:
- weather stripping
- speaker wire ( I had some 18 gauge stuff lying around the house, the project only needs a few feet.)
- heat shrink tubing

Comments

[applefanatic]

hey didnt kipkay do something like this?

[mzed]

That comment comes up periodically here. In 2009, I wrote:

"Kipkay did a weekend maker video based on my article in Make. However, I am far from the first person to do this. Check out the link to Dan Truman."

[leothelion]

do you guys think a metal bowl would work well in terms of how it resonantes etc?

ikea now sells these: http://www.ikea.com/us/en/catalog/products/50057254/

pretty good price.
thoughts?

[speaker_serhiy]

what terminals are you useing in this project, the link you posted doesn't have those terminals.

[imolenaar]

i cant get it everyone says just hook up one speaker to an amp output but normal boxe`s of my radio has 4 speakers in each and just one cable

[TOCO]

Hey, great instrucable. It reminds me of a weekend project a while back. By the way most of your links appear to be broken.

[mzed]

Thanks. Mostly fixed now.

[TOCO]

You are the first one that has actually fixed the links when I tell them that they are broken. You did it so fast to. Now the instrucable is even better.

[mg0930mg]

Some people posted instructables in 2007 and never came back. It also takes time, and some things that go missing, you can't ever find anything with the same information.

[mzed]

I'm still here. Ikea stopped selling these salad bowls, though. Making an exact replica of a project doesn't seem to me to be very important, anyhow. Hopefully there's enough here to get the idea out and somebody can make a nicer version with whatever is available at the time.

[Phoghat]

Okay, I just saw this and wan't something similar. I've got some questions:
1 Does the one speaker do stereo ? Or am I missing something. If it's not stereo = 1, why are there 2 sets of terminals?

2 I live in Mexico and you can buy bowls like that everywhere for a dollar or 2. About how big are the bowls in diameter ?

[mg0930mg]

Yeah, I see what you're saying.

[TOCO]

Man, it has been forever since I actually did anything on this site. I come and glance at the first page once every couple weeks but it has changed so much from when i joined I dont really like it.

[mg0930mg]

Same.

[hvargas]

how much did this end up costing you?

[krish98.sai]

This is so cool, did you know it was presented on make magazine videos with Kipkay

[Madsengell]

Hey check out this project from stanford laptop orchestra (SLORK), I believe they are also referring to this project:
https://ccrma.stanford.edu/~njb/research/slorkSpeaker/index.htm
Great work by the way!

[applefanatic]

hey kipkay did thi project great job it a exact replica lol cool :)

[plasticpopcorn4]

is this a pretty common project? did kipkay rip it off? I just saw the vid too

[Johenix]

Why not use 12 speakers arranged in a dodecahedron (solid of 12 pentagonal faces)? The speaker case could be made from card stock or foam core. Or get the type of speakers TerraCycle gets to make speakers in recycled cardboard cases.

[JonnyDude2008]

Make it, although you might find if the speakers are perfectly arranged (as in same spacing between each one) it could look dull. Plus try different sized speakers that would give it a cool twist.

[FrozenStar]

Interesting design, looks great.

[fady youssef]

ya i get it but how i will conected to the radio

[Dark Carver]

You could solve the whole input problem and wire up a headphone jack to the speakers. That is, if your radio has a headphone output jack. But then I guess you would have to give the speakers there own power supply.

[lwil]

you need to put it through an amp and connect the speaker outputs to the red & black inputs on the sphere

[mattyuke]

Connect it to your stereo on the connectors like in the instructable

[vez87]

what sort of amplifier would you use for this as I'm looking to make something similar to wire to a 3.5mm jack for mp3 use, and I doubt that the player will be able to power the speaker all on its little ownsome.

[tomigm]

Only 1 word.... C.O.O.L

[Jeff K]

dont use anything but the batting. Cloth or foam is too dense and will deaden the sound. You can stuff the insides, just dont pack it. You need the sound to resonate thru the polyester dampenig material. The key is that all the gaps from the seams and mounting around the speakers is air tight.

[FrasterKoler]

 It's a very creative idea, BUT the sound waves of the speakers will work AGAINST each other...!

A speaker (when in use) sends sound waves to the front but also to the back. SO when you put 2 or more speakers with the backs  +- facing each other in the same space, you get a loss of sound and quality.
In such a project, the space in which the speakers are needs to be divided.

Also, the casing is to light for such and so much speakers, the vibrations will cause the casing to resonate, and resulting in a a unclear sound. It will just work well on low volume... but with these kinds of speakers i do not suppose you want to turn the volume down!

[tim_n]

Stuff it full of foam?

[Jeff K]

Not foam, polyester. And be sure the 2 halves are sealed. They need to be well sealed, or you will lose your base.

[FrasterKoler]

Polyester like a wall between the 2 hemispheres of the ball? it will already work better, but sparating each speaker from the rest would still be better.

[Jeff K]

Polyester like batting, acts as a dampener inside the sphere. My GB-1E's had a large piece covering each speaker inside the sphere plus wadded up inside. Dont pack it , lightly stuff it. You can get the polyester at radio shack, or spend half the money at a fabric store or walmart. No wall betweem the halves, my comment was related to the seal of the system because this is not a ported speaker. The term the origional speakers literiture had was "Hermetricaly Sealed", similar to a passive radiator type speaker system. Depending in your skills, a 1/8 in thick bead of clear silicone will work just fine. Its your choice as to weather you let it cure (24 hours) prior to assembly, or use it as an adhesive seal. Just be sure all the speakers are working prior to addhearing the two pieces togeather. Worst case, the silicone can always be cut to seperate the halves with a razor knife, if repair is needed

[FrasterKoler]

Exactly: a dampener. Separating the speakers from each other, so the soundwaves dont ''mess' with each other, and put like: wads (i hope this is the correct word...), cloth, or something soft inside which damps the sound, resulting ina fuller sound. =)

[FrasterKoler]

How do mean sutff it full? also the backsides of the speakers?

[Jeff K]

FYI, I have a set of speakers that I bought overseas back in the late 60''s. they still sound as good as a set of Bose 901's. There are 8 speakers, of which 4 are hi dome tweeters with a built in crossover inside. Optimum placement is each globe is suspended in a corner, and the legnth of the chain should be the same distance from both walls and the cealing. The principal is the same as the Klepsch Infinate Baffel, where the walls and cealing are the final projector of sound. I tell you there is a huge difference in the sound as opposed to being on the floor. You google Nivico GB-1E, You can see several others like it at http://www.flickr.com/photos/teddy_qui_dit/4190293419/in/set-72157622584019059/

[Madsengell]

in order to simplify the amplification, these speaker distrubutional hubs (or the like) might do it, although i don't know how it affects the amplification. Can anyone help there?
http://www.nextag.com/speaker-distribution/compare-html
will they be connected in parallel then, and in that case would it still be sufficient just to connect to your amplifier?

[rugnor]

i think you could also use a buoy  if you find it floating in the sea, the rule of the sea find it , keep it

[3rdmike]

Excellent instructable.  And bonus points for humor; beer and espresso are what fuels the DIY'er. 

[Sandisk1duo]

i have a question about polarity, when connected properly, how does a speaker move? out or in?

[askjerry]

As the phase of the current changes the magnetic poles will be forward, then backward. With reference to the rest position the speaker cones will move in either direction. It is therefore important to observe polarity as failure to do so will mean that while one speaker is moving outward another would be moving inward. The result is that the two acoustic waveforms would be in opposition to each other and would (at least partially) cancel each other out.

You can take two speakers and connect them correctly then play some music... switch one and the music will sound flat and "hollow" because of missing spectra due to cancellations.

Jerry

[mzed]

I believe both ways.

[Sandisk1duo]

then what's the difference?

[mzed]

None, except that the signal is 180-degrees out of phase if you switch the polarity. It only matters with multiple speakers.

[Sandisk1duo]

so, from what i can understand, if half the speakers are wired right, and half of them are wired wrong, and you blast music, you shouldn't hear anything. I mean the sound waves inside the speaker will cancel themselves out right?

[vahdad]

In the "real world" only the bass frequencies will cancel out.  No matter how much you crank up the bass, or how much you add the sliders below 100Hz, you will have a net ZERO effect on the sound.  If all are wired correctly (ie: all positives and negatives wired to their respective terminals) then the bass will bellow when you "blast the music".  Again, this comes not from theory, but from many, many, many hours and gigs, and rewires of professional grade sound equipment...rented to bands that were "less than gentle" with the goods.

[endolith]

so, from what i can understand, if half the speakers are wired right, and half of them are wired wrong, and you blast music, you shouldn't hear anything.

No. You'd still hear sound, but certain frequencies would be missing at certain points in the room, due to destructive interference fringes. (This still happens even with everything wired correctly, though.)

[Goddard]

First of all, there is no WRONG way to wire a speaker. You may wire them differently from each other, but one is not right and the other wrong. Remember, speakers emit sound into 4pi steradians. If two drivers are wired in push-pull mode, then you must include HOW the two speakers are aligned with respct to the other. If they are pointed in the same direction, and mounted on an enclosed box, then on the inside of the box, you have one speaker pushing air IN while the other pulls air OUT. Hence, there would be no net change in cabinate pressure inside. On the outside however, it's wide open so the same rule doesn't apply. If each speaker were a point source, AND on top of one another, AND if they both emitted the exact same frequency or wavelength, then you would have total destructive interference and no energy would come out. But this is not what you have. We have two extended area drivers adjacent to one another, both emitting a wide spectrum of energy (frequency range). so it becomes a different, but similar problem. Depending upon their separation, their diameter, and the clocking, you will get destructive and constructive interference in push-push configuration. In push-pull, it will be different. I don't think you want to push-pull speakers facing the same way. You will not get full cancelation but it will alter the sound radically, and be very sensitive to the off-axis angle. Push pull is reserved for dipole speakers facing opposite directions and even that is sensitive to cabinate design. Go to Siegfried Linkwits's web page (Orion Speakers). You will learn much from him. Oh, and blasting the speakers will not change the basic physics of interference.:-)

[shooby]

In theory, i.e. with perfectly symmetrical geometry and resistances of wires, etc, yes. In practice however, no, never. Too much randomness in the system. In theory you could find regions of silence between two 'spot-light' speakers, but that once again is in theory.

[dhnobles]

Someone should be sure to mention that how you wire the speakers (series/parallel combo) should depend on the impedance of the source you are driving them with and the impedance of the speakers. Most home stereos have an 8ohm output and most aftermarket and good OEM automotive speakers have a 4ohm impedance. BUT some OEM automotive speakers have 12 and 16 ohm impedances. So be sure you check the speaker (look at the magnet its usually printed there) and adjust your design accordingly.

[urwatuis]

   This is a very cool idea for outdoor speakers on a patio or deck. It could be wired so each bowl is 1 channel of a stereo out put with 4 speakers in each bowl so you have a left channel bowl and a right channel bowl. Its been quite a few years since I did series and parallel circuits but I think I have it correct below. Feel free to make corrections if I am wrong.
    Most stereo receivers can have from 4 - 16 ohm nominal impedance speakers connected to its outputs. If the 4 speakers are wired in series the impedance is additive and so 4 * 4ohm speakers = 16 ohms total impedance which will be fine for most receivers. 4 * 8 ohm speakers = 32 ohms which would be too much impedance and, I believe,  would seriously degrade the volume though would not damage your amp.
    If you were to wire the 4 speakers in parallel this might be a problem as the total impedance is 1/Rtotal = 1/R1 + 1/R1+ .....1/Rn or R1*R2/R1+R2. Using the second equation if you connect 2 - 4 ohm speakers in series you have an 8 ohm circuit. then if you connect these 2 - 8ohm pairs in parallel you will have 8 * 8 / 8 + 8 = 64 / 16 = 4 ohms which will also work with most receivers.  If you connect all 4 speakers in parallel then you would have 1/4 + 1/4 + 1/4 + 1/4 = 1/16 ohms and this would not be good for the output transistors of you amp or receiver.
   I hope I got this right and it is of some help. I am going to try this myself and use the speakers outdoors hanging from the roof of the porch.

[sparky12345]

dude!! 

[JAZ97]

so sik dude
im subbin

[recordmasta001]

didnt kipkay do this first?

[robo3]

ya he did

[mzed]

Kipkay did a weekend maker video based on my article in Make. However, I am far from the first person to do this. Check out the link to Dan Truman.

[headinmysights]

Maybe it's just me, but for somebody who just wants an interesting speaker to play music, not in order to try and make more realistic electronic instruments like you, wiring the speakers up would be more efficient. You save on terminals (one per hemisphere) and it'll be easier if you bring it with you somewhere in order to hook it up to an iPod or something.

[D.L.H.]

This is pretty cool

[FaqMan]

This design is pretty cool.

[mweston]

Another thing to do would be to fill the inside of the bowls with a polyester filling to take up any extra space. Cool project though *favorited*

[shikaku]

are these in series or in parallel?

[mzed]

Neither. Each speaker is wired directly to it's own terminal.

[shikaku]

so to have an input, it would have to be split and thrown into all those terminals? that seem like a lot of wires going in. so i should install all the termainals on the top to keep wires from all over it? or do i just not get it?

[shikaku]

oh you do have them installed on top... i see. ok...im dumb

[Da_Fudge]

if you were to reverse the speaker connections, it actually would have an effect. where the music had a drum beat, the speakers would normally push out. but if you had one speaker reversed, it would pull in. A simple way to test this is to get 2 speakers. feed them with exactly the same level and music, but reverse the connections on 1 speaker. it ALMOST cancels out all the music. notice I say almost, because no 2 speakers can move identically.

[Goddard]

It's called 'push-push' or 'push-pull' depending upon the connection. Two speakers wired identically are 'push-push'. Switch the wiring of one speaker and it's 'push-pull'. No cancellation will take place if each speaker is facing the opposite direction. It's like a dipole (Orion Speakers). Facing them the same way MAY create some cancellation in push-pull, but not much. As for spherical arrays, all they are doing is trying to emulate a point source of energy. A point source radiates energy in a spherical wavefront. If you put an infinite number of drivers on the surface of a sphere, and point them all outwards, and hook them up the same, then you will emulate a perfect spherical wavefront. The fewer number of drivers you have, the less perfect the wavefront because of diffraction and destructive interference. It's a physics thing. Like if you stack two tweeters in a cabinet and one is sitting above the other, the sound will cancel in the horizontal direction if the speakers are not placed close enough together. Cancellation in the vertical takes place BECAUSE of the proximity of the two drivers and this prevents, or suppresses the vertical dispersion that can reflect off of ceilings and floors. That is why you only see speakers stacked vertically, not horizontally. You do not want cancellation in the horizontal (parallel to floor) direction. It would drive you crazy. One chair you can hear everything but move 2 feet over to the couch and the sound is way different.

[mzed]

Thanks for your thorough descriptions. I should also point out that in this array the speakers are all acoustically coupled by the air mass in the bowls. In other words, movement of one driver will effect the others -- making this a very crude approximation of a point source.

There are some heavy academic papers here about what can be done with the 120-driver Meyer array. I think they can form about a 30-degree beam with that one. That thing is the real deal, in terms of science. My salad bowls are "fun."

[Oimi]

Could you please update the links? And provide alternative links for those of us in the UK?

[Oimi]

Hello, please?

[mzed]

I've updated all the links I could. It will take me a while to learn about electronics suppliers in the UK, though.

[Oimi]

Please let me know when you have updated the links to include those for residents of the UK.

[NJB]

in the UK, try Maplin, failing that, Ebay can usually turn up most odds and ends.
http://www.maplin.co.uk/
http://www.ebay.co.uk/

[Oimi]

But I don't really know what I am looking for. Thank you for those suggested links but surely it would be more useful if you could direct us folk in the UK to a specific page for each item (on maplin.co.uk for example).

[mzed]

These speakers look very similar to the ones I used.
Get some speaker cable and some [http://www.maplin.co.uk/Module.aspx?TabID=1&åModuleNo=44212&doy=4m8 terminals] and you should be in business.

NJB: Thanks for the Maplin tip.

[mzed]

Also, type A of these speakers looks promising.

[Oimi]

Wow, thank you for your response! All the links are god except the "terminals" one which directs you to their home page.

[mzed]

<br/><a rel="nofollow" href="http://www.maplin.co.uk/Module.aspx?ModuleNo=44212&criteria=speaker%20terminals&doy=5m8">try this</a><br/>

[Oimi]

Great, thanks!

[Oimi]

Thank you, really appreciate this!

[Redgerr]

that looks sweet lol, wonder if it works as well as it looks lol :) thanks for the instuct

[JellyWoo]

i tried to click the links for buying the speakers but none of them work. Neither does the speaker terminal links. please help.

[mzed]

Links fixed. Once again safe to surf teh interwebs.

[mzed]

It seems that all electronics has redesigned their website. I'll find some new links.

[JellyWoo]

the speaker terminal link still doesn't work.

[mzed]

Sorry; they don't seem to have that speaker terminal any more. Try the Radio Shack link.

[JellyWoo]

oh, okay

[ianskiin]

I know this sounds like a dumb question, but could you paint the cones? Would it have any negative effects, or would the vibrations just wear the paint off? ...BTW, Nice instructable, and great idea!!!

[Kohler]

You could also look for ones that are already painted like from Computer stores.

[mzed]

First, thanks. Second, I think that paint on the cones would tend to dampen the frequency response of the speakers, especially the high end. You could try it and see; maybe the effect is not enough to bother you.

[ianskiin]

I might try it on my cheap computer speakers, because they don't sound that good anyway. It shouldn't be that hard to get off...

[Patented]

I like it it has a great look! +1

[rebuscador]

love interface work, and we were thinking in copy their speakers array for our gigs with cello+electronics... so thank you very much!!!

[drcrash]

What is a spherical speaker array good for? (I assume there's something, but I don't know what it is.) Most speakers are intentionally designed not to radiate equally in all directions, because the sound coming off the back of the speaker reflects of walls and things, and interferes with the direct sound from the driver. I'd think that a spherical speaker array would be a bad investment. All those drivers cost money, and for the same money you could buy one loud, really good-sounding speaker and put it in a conventional enclosure. On the other hand, some serious people seem to have put serious effort into developing these things, so there's probably some reason. So I have to wonder when this kind of speaker enclosure makes sense, aside from looking cool.

[drcrash]

I asked a friend who knows about this stuff what these spherical speakers were designed for... and it's not your usual PA or home stereo applications. They're designed to make electronic instruments and recorded music fit in with live acoustic instruments for a live performance. The usual thing for a stereo or PA system is that you don't want the speaker to radiate in all directions, so that you can suppress the room acoustics to some extent (e.g., not hearing reflections off the wall behind the speaker) and the listener will mostly hear the "room" acoustics recorded into the music, or added with reverb effects in a PA system. That doesn't work so well for mixing live mostly-acoustic music with electronic stuff played through a normal speaker, because the acoustic instruments radiate in all directions, the listeners hear the room acoustics, and the "acoustics" engineered into the electronic music don't match what the audience is hearing. To make the acoustic an electronic stuff blend into the same "sonic space," you make the electronic instruments radiate in all directions too. (And maybe radiate somewhat different sounds in different directions, as acoustic instruments do.) This is not generally what you want for a home stereo, or jamming in your garage. It'll make music recorded to sound like it's in a big hall sound more like it's in your little living room, or emphasize the nasty acoustics of your garage. For most people's purposes, a conventional speaker is better-sounding. (But no as cool-looking.)

[DIY-Guy]

Spherical speakers have been around since the 80's or maybe earlier. The Electrical Engineer George Carlson in Cardiff California invented a spherical speaker which was so efficient that only TWO were needed to fill the entire San Diego Sports arena with full sound. The arena is lozenge shaped and one speaker was hung at the focal point at each end. His speakers were so efficient that they could be driven from the earphone output of a micro pocket radio, OR driven up past 1000W with an amplifier. The project had obvious military possibilities, hollywood possibilities, and just plain audiophile-fun potential. The frequency response was nearly perfect from 1hz to 20khz. It's great to see somebody doing this with salad bowls, that puts it into the hands of the public and prevents powerful groups from keeping this for themselves!

[urlostinmyworld]

interesting.. i never thought of that!

[mzed]

Very well said, thank you. Recordings mixed for regular stereo or 5.1 are going to sound different than what the engineer intended if played through a spherical array. My work with this speaker has been totally directed at projecting sound I make. I think this would be a cool alternate to a traditional guitar amp, for instance. As you said, the radiation would help electric or electronic instruments blend with a mixed ensemble, and seem more "natural."

[gaara0sama1]

Is it possible to turn these into an mp3 speaker or radio/sterio speaker? If if is can you tell me how?

[tudgeanator]

i might make 1 of these for our music room-i could put a jack socket in it,use mini smokey amp speakers and play my guitar through it!that would be cool!

[spike shadows (secret agent man)]

skeys are awsome but not worth 35 bucks. might anyone know of a way to build a good knock- off and/or copy though?

[mzed]

I think there some little amps already on instructables. Based on my comments from this project, though, I think that I should probably work on an 8 channel amp project. The electronics aren't so hard, but I've yet to find the right enclosure...

[spike shadows (secret agent man)]

put a output for a sub on it then see if you can make some 8.1 surround sound lol

[eriklares]

SALAD BOWLS??? great idea.... lol, the people on this site are ingenious!

[eight]

Does it come in Blue ? : ) Dolby Pro-Mono ;P Fun aside, nice project !

[loogielicker]

Does it ever.

[LakeLivin]

What would seem cool to me is to use some of that textured 'stone' spray paint on the casing (bowl) before assembling the components. Although adding extra cost and an extra step, that would take it from a cheaper 'plastic' look to something that looks much more solid and expensive. Nice project as is, though. I'd love to hear these before going to the time & expense of making some.

[SpaceRat]

I have an idea I am going to try with this idea: Instead of the plastic bowls, I am going to take a cheap plastic ball, about 14" in diameter, and cover it with fiberglass and resin. When it hardens, I will merely use a hole saw to make the holes for the speakers, and then remove the (now deflated) plastic ball. I can then paint it with black texture paint, and have a nice, prefectly-round speaker box. My hat is off to MZED for giving me the idea!

[LakeLivin]

SpaceRat- if that works you might have room to mount the speakers from the inside and use grills on the outside for a more finished look. . .

[alexjag33]

Yeah, but does it shoot laser beams at Jedi in training?

[mzed]

Why yes it does! Unfortunately, the come out as really fast-moving Lissajous figures, so I keep getting my butt shot.

[coolguy]

if you wanted to solve the structural issue you could vacuum mold a negative from the outside, customize the shaping (using fillers), and fiberglass the interior of the negative to recreate the two halves.

[fuzvulf]

I still love it. Saw a post talking about only being able to find translucent bowls. Why not? Add some sound reactive cold cathode or LED lighting with a remote and you got retro disco with a new twist. Fuzzy

[Falaco Soliton]

ingenious. and im with SpaceRat. I need some basketball shaped speakers...

[ujj]

Can this really take the weight if you hang it from the ceiling?

[xbattle xwar]

I think it will, cuz the ceiling is pretty heavy... and the Speaker Array thing looks light. Am not the one who invented it, but kinda guess...

[mzed]

If you make one, you certainly should be careful. Obviously, the bowls were not designed to hold this kind of weight. And, I can't speak for your ceiling. The one I built seemed to be up to the challenge. I would not swing it around my head like a medieval weapon (even though I might like to). Under a static load, I am somewhat concerned about the holes in the handles pulling through eventually -- that's one reason I used a fat carabiner. I don't think that kind of failure would happen quickly, so I would suggest inspecting it periodically if it was permanently mounted.

[ujj]

Thanks for your reply mzed. When you stack the two bowls together, do they end up looking like a sphere or more like an egg.? What are dimensions when stacked together?

[mzed]

It's egg shaped. I'm going to borrow it back soon. Roughly, the bowls are 9" in diameter. The longer diameter might be 12".

[fuzvulf]

I like it, cool instructable. Got some old dolby surround speakers laying around, think I might add a port and mount the whole thing to a cieling joist using a section of PVC pipe using the pipe as a port and use an adapter inside attached to the pipe with the pipe passed through a tight fitting hole to hold the weight.

Now its time for a sub woofer to match. Here is a link
to a commercial one for maybe some ideas.

[allfiller]

would wiring 8 speakers in series/parallel be a bad idea? i'm considering using a setup like this (possibly two simultaneously) to run my bass through and i wouldn't want a .5 amp load. i don't know much of anything about wiring, but would wiring them that way be safe?

[cylver]

If you have two speakers in series, the resistance is doubled. If you have two in parallel, it's halved. So 4 speakers in series parallel (two parallel sets of two speakers connected in series) work out to be the same as one higher wattage speaker, and two of THOSE wind up being a quite acceptable (though not perfect) load for your amplifier, as long as the total wattage works out right.

[Staples]

Exactly as cylver said. If you do this per hemisphere you'll have a perfect speaker load for your left channel and right channel. Going with one hemisphere at a time, if you start with a quantity of four 8 ohm speakers you can end with a single 8 ohm load. Take two of the speakers and tie positive to positive and negative to negative, do this again for the other two in the (same) hemisphere. Now you have 4 conductive points to work with (+, -) and (+, -) next tie the negative from one of the two sets you created to the positive of the other set you created and isolate it with wire cap, heat shrink , etc. (+, -+, -). You should only have 2 conductive points and you can test them with a voltmeter / DMM to verify resistance (Ohms). Now do the other hemisphere and you'll have your two channels for L & R. If you start with 4 ohms speakers you'll just end with a 4 ohm load. I would think if you use four of the same speakers the peak and rms power capabilities would be a sum of all 4 due to keeping the final resistance the same, thus the 40/70W array used here would turn into a 160W RMS / 280W peak speaker - should be capable of some high db output and need a good size receiver. This may be common knowledge to some but I didn't think it would hurt to expand on a bit.

[robolicious]

Can you tell me how I would wire it for one sphere per side. ie the whole sphere (8 speakers) will be one channel

[Staples]

To make a 4 ohm "sphere" use 8 ohm speakers and make two hemispheres as above, then parallel them. That will be putting the positive wires from one hemi. to the positive wire of the other and doing the same for the negative side. (+ , +) and (- , -) you'll end up with one 4 ohm load.
To finish with an 8 ohm load build the hemispheres with 4 ohm speakers and run them in series as in the 2nd step above. That will be connecting the negative ( - ) from one hemi to the positive of the other, then isolating that connection. You'll end with two wires one from each hemisphere one positive one negative and a total load of 8 ohms, again if you have a multimeter handy it'll help verify connections. Either way you'll have some speakers that are capable of heavy duty power so I'd look for a very big receiver! (4 ohms, 8 per channel 320w RMS/ 560W peak per channel, X 2 channels = 1120 Watt peak) Anybody got a 1000w receiver and some looney toons sound effects we can play with? It's been a while since I ticket off the homeowners association : )

P.S. If I forgot to say it "This is a sweet project" !

[allfiller]

Thanks a lot! I love this website. i'll try and post some pictures when i'm done. i couldn't find the red bowls though, only the crappy near-transluscent white ones. Happy tinkering! :)

[Sgt.Waffles]

Looks great! And that gives me an idea. I have a couple of stuffed squirrles that i have shot. I want to put speakers in them.

[fighter pilot]

be sure to post that!

[canida]

I certainly am interested!
Sounds like a neat project; good luck sourcing materials. I hope they're fat squirrels...

[T3h_Muffinator]

HAHAHA! NOW THAT'S MANLY! Notify Christy if you do, I'm sure she'll be interested!

[Sgt.Waffles]

Yeah, i need to find decent quality speakers that are small enough to fit in their body cavity though.

[fuzvulf]

penguin speaker linkI don't know, would these work?

penguin speaker link

I mean like do a gut transplant operation from a penguin to a squirrel?

[SacTownSue]

Sgt. W The squirrel speaker is pretty creapy. Then I looked at the penquin speaker and I saw that the wings of the penguin move up and down. What if you did that with the squirrels? Yikes! I'm outa here!

[mensmaximus]

Hi, I mounted six varying diameter speakers onto two 4 ft high wax 'stalagmites', with one flat side. They worked so good I blew them all out at high volume. They are all replaced now but not wired up yet. Hope I'm on topic. Consider mounting electret microphones on rubber diaphrams onto a sphere. Search Holophone.

[candle360]

nice idea but i don't have money or time to make one. Could you send me one? or something... my e-mail is [e-mail]

[tescavko]

Clear bowls with LED's that are sound activated! Sooo cool!

[candle360]

sorry I meant to put also to e-mail me...sorry

[candle360]

I like the idea of a blue one though...Dark midnight blue with black highlights or vise versa

[red_metallic]

I love seeing projects like this. I've worked for several speaker manufacturers over the last 20 years and have heard a number of "pulsating sphere" type designs. They quite surprising in how good they sound with modest parts. Nice work! Some things you might want to consider for version 2.0 - (1) Building up a stereo pair instead of the combined stereo as above. You'll get a better soundstage, more output, and greater power handling. You'll also double the cost. (2) Adding a tweeter directly on the front of each facing towards the listener with an L-pad to adjust the output level of it can improve the realism quite dramatically. (3) Lastly is to use this with a subwoofer, also a good DIY project. It will improve the overall bass output & realism.

[Odziz]

Brilliant! I like CameronSS idea of making it wireless, you could glue those small square mirrors onto it and have a Speaker Mirror Ball. Wow, get down and boogie

[berserk]

Must be nice to live near an IKEA... the closest is ~800km from where I live. I am sure there are less fancy bowls available around her... :-)

[mje]

Actually, any speaker will radiate omnidirectionally at frequencies whose wavelength is greater than 4x the diameter of the speaker. So 4" speakers will radiate omnidirectionally at all frequencies below 2.5KHz. Stil, an interesting project, and one that would make a pair of neat computer speakers.

[mzed]

I think the wavelength of a 2.5k sine tone is only about 13.7 cm, so in your formula a 3.4 cm speaker would radiate omnidirectionally below that frequency. I'm looking here:

http://www.sengpielaudio.com/calculator-waves.htm

A 4" loudspeaker speaker driver would have a diameter of 1/4 wavelength at around 850 Hz. Then,I think there's some further interaction between the driver's radiation and the enclosure in which it's mounted.

But these are details. The important concept that you are telling us is that it would be fine to make this project with tweeters, and pair it with a (single) subwoofer. Not only are speakers not as directional at low frequencies, but our auditory system does not localize low frequency sound as readily.

[mje]

Sound travels at 1000m/s, so an 850Hz tone has a wavelength of 1000/850, or roughly 1.18m. A quarter wave is .295m, or 11.6 inches. You may have made a units conversion error. But yes, it's not a bad idea to do this with smaller speakers and use a single woofer. And yes, you can't really localize a sound with a wavelength that's large compared to the distance between your ears, as you can't detect the phase difference.

[mzed]

Sound travels at ~ 344m/s (which is approximately 1100 *feet*/s) at sea level at 21 degrees Celsius. If you don't believe me:

http://www.grc.nasa.gov/WWW/K-12/airplane/sound.html
http://hyperphysics.phy-astr.gsu.edu/hbase/sound/souspe.html
http://en.wikipedia.org/wiki/Speed_of_sound

[mje]

BTW, the idea of a polyhedral or spherical speaker enclosure is an old one. There have been commercial cabs like this going back to at least the 60s. One of the the best way to make a cabinet "disappear" and appear as a point source is to get rid of early reflections- those coming off the face of the cabinet. One way of doing this is to caver the area surrounding the speaker cone with something that absorbs sound, like heavy felt.

[mje]

You're right, I was wrong, what was I thinking? Mea culpa.

[Ohm]

So you have four sets of two speakers wired in parallel? Would it not be better to wire two of the two paralleled sets in series to one terminal so that is would be stereo and 8 ohms, instead of 4 ohms? Anyhow cool speaker, what is the sound quality like with it? I think I might have to give this one a try, just for the fun of it.

[mzed]

Sorry, I should be more clear. Each speaker is wired individually. Each terminal handles two speakers, so four terminals = eight speakers.

I thought the sound quality was better than I expected. The speakers are quite good. Unfortunately, I gave this one away almost immediately, so I didn't run it through rigorous testing. The person I gave it to likes it, though. :-)

[StepsoftheSun]

Awesome work! The final look is very cool. Do you think music actually sounds better when the speakers are configured like that?

[twisted]

woah. thats kinda awsome. Im gunna make myself one! i just need some speakers...

Great idea and instructable
~Twisted

anyways, check out my wallet instructable: here

[nagutron]

Lame plug, man. It's cool to link to your Instructable because you want pageviews for a contest, but it only makes sense if it's relevant to where you put it. Otherwise, you're a dirty spammer and you smell like one, too.

[CameronSS]

Hmmm...If you could make it wireless, and put an old Li-Po battery in, you could play catch with a talking ball, or hide it around the house, or wear it as a hat, etc.

[mzed]

It's surprisingly heavy. Add a battery, and it could be downright destructive.