After years of hearing about an ideal point source, I wondered what one sounded like. Well, you can’t make an infinitesimal speaker, but you CAN make something which simulates the wave front that would propagate out from a point. All you need is a spherical speaker. Maybe a rubber balloon which inflates and deflates at an audio rate. Ummm, maybe not...  Maybe an inflated ball of piezoelectric plastic film, which I remember was developed in the late 1960s. So whatever happened to it? Seems to have disappeared. Maybe an array of conventional drivers arranged in a sphere or on the faces of a dodecahedron, or...

Turns out the last idea has been done many times in research labs and occasionally for electronic instruments for performance. Not often tried for listening to music, tho. The first commercial speaker array from Dr. Bose was a large 1/8 sphere which occupied the corner of a room covered with a large number of smallish 4” drivers. I heard about it but never heard one. Not everybody has two free corners in their listening room for a geodesic beehive covered with speakers. Cutting the number of drivers to nine and using an equalizer made Bose a hit. But the Bose 901 isn’t really a point source. It’s more a sprayer of diffuse sound reflected off the back wall. If you turn them around so the 8 drivers face the listener...  closer, but not a spherical wavefront. More like a pair of spotlights from each set of four drivers shining from each speaker.

OK, how to have a reasonably quick and cheap listen to a pseudo point source? We’re looking for a spherical array, or a hemisphere hung on a wall. Full range drivers, because even distribution of multi-way drivers and crossover makes my head hurt. Small drivers, to keep high frequency beaming to a minimum. My eyes lit on the round 1.5” drivers for my Mac G4 Cube. H/K Genesis, very decent sounding, fair power handling, and there were several of the Apple plastic ball speaker sets down at Goodwill. So I started collecting them. It took about a month to scrounge four sets of Apple G4 Pro speakers.

Enclosure. No wood tools beyond an electric drill and sabre saw in my garage. Very limited capability there. But there are articles online about spherical speakers built for electronic music performances using serving bowls. IKEA to the rescue! Blanda Matt wooden salad bowls have been used for all sorts of round projects. Simple woodworking, then. A 2” hole saw to bore holes for the drivers, a Lazy Susan tray or two from Wal-Mart, and off to the garage to make sawdust.

Some small carpet squares glued in with roof patching tar provide damping. Drivers are a tight friction fit. No fasteners or glue needed. Wired in series - parallel 2x2, 8 ohms.

So what do they sound like?

First off, they aren't as efficient as R-S Linaeums, needing about 8dB more oomph out of the amp, with a corresponding cut to the subwoofer level. They are smooth sounding up to fairly loud levels (well above my normal level) where a metallic raspy breakup begins to make you cringe. Highs are plenty present despite the rapid falloff measured above 10KHz. Listening hard, there's some lack of shimmer on cymbals, but then my hearing above 10KHz is not so hot these days. No obvious "jug" resonance, which I was worried about from the round enclosure. Damping is adequate.

They throw a solid image which stays put as you move around / sit / stand. There is a sweet spot, or rather a fairly large sweet area centered on the apex of an equilateral triangle with the speakers. Image extends from a couple of feet outside the speakers all the way between, and has considerable depth depending on the recording. Renée Fleming on "A Love Like This" with Charlie Haden (Sophisticated Ladies) sounds like she's right in the room, and the quartet is right behind her. On the other hand, vocals on Steely Dan's "Gaucho" are set well back among the instruments, which is not so pronounced with my other speakers. Orchestral music sounds full and naturally balanced, but on extreme dynamics, you either lose the softest parts in room noise or run out of headroom on the loudest peaks. This might be amplifier clipping (40W / chan chip amps) but I am dubious about hitting 2" speakers with my 200W big amps. Sharp transients are crisp without any smear. In all, I rate them a success. Easy to listen to, if a couple of degrees less refined than the modded Linaeums or Quad 57s. Well above the run-of-the-mill. Certainly couldn't have bought a pair of anything as good for ~$50 build cost.

Next, I want to set them up with their own sub woofer, either an 8" RCA from Rat Shack, or a KLH out in the garage. If they do as well as expected, they will likely get hung on the wall in the family room or perhaps the bedroom.