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As I put it in my Munich 2008 show report: "Another very sharp cookie is Aleksandar Radisavljevic of Raal Ribbon. While presently in the raw driver business -- Edwin van der Kley of Siltech is very impressed and far from the only one -- Aleksandar has his sights set on his own speakers. They will include omni ribbons, a concentric 24-driver midrange array and 2 x 15" active woofers. Fellow manufacturers alert: Raal is very flexible, capable and willing to accommodate custom requests based on their core competency of ribbon drivers. If you need something special like a 110dB ribbon, Aleksandar is your man. Some people are so smart, they shine. This gent is one of 'em..." [Photo by Marja & Henk.]

Little did I know at the time that Aleksandar would see fit to organize this RoadTour Serbia. Nor that 6moons would be privileged to become the press pipeline to document the real-time development of the above speaker project. On August 24, a day after the mid-September dates for the RoadTour just prior to the Milan show had been fixed, my inbox saw me the recipient of a Raal e-mail. It had also been sent to nine other gents. The subject header mysteriously read Bronze for 'Eternity' omni speaker. The tie-in with the just-concluded Beijing Olympics was, as it turned out, entirely coincidental. There were no comments, just 14 full-size jpgs, all of them variations on this one which said all:

Bronze, as it turned out, was the actual material for an omni woofer enclosure. The drivers' size couldn't be ascertained from the photos alone but a subsequent answer from Aleksandar to my instant Sunday afternoon inquiry added to the enormity of ambitiousness involved in this speaker project (of which, as we shall see, the bass is merely the beginning):

"This is a woofer housing. There will be 5 x 15" woofers and one hole. All that is, in fact, a U-baffle. I will use the acoustical resistance on the hole to get a cardioid dispersion pattern in the bass as I'm not a fan of the figure of 8 pattern." The latter, to interrupt our designer for a moment, is the well-known challenge of dipole panel and open-baffle speakers which suffer partial bass loss due to out-of-phase cancellation between the front and back wave. "In the cylinder above the woofers, there will be an 18 x 3" cylindrical array of full-range drivers serving as a midrange and one omni tweeter with 15 ribbons. About 170 cm tall in total. This speaker is named Eternity. This will be serial product, most probably run in small editions of 12 pairs each. My friend who designed and sculpted the woofer casting can make a different clay model after that, or make a custom sculpted surface for a pair. Each bass sphere pair takes 130 hours of work by the foundry plus 4 days of baking the molds. Sculpting is separate and not quantifiable.


"The casting is the same as it would be for any artistic sculpture in bronze - by lost wax method. There is no better method if you want to get all the details but there are worlds of differences in quality between different foundries. I work with the best one, owned by a guy who is a sculptor artist himself and has a Ph.D. in that. Here's the link for a video of the casting process.
Prof. Nikola "Koka" Jankovic, sculptor; Zoran "Kuzma" Kuzmanovic, sculptor. The sculpture in the back is Nikola Tesla, made 30 years ago by Prof. Jankovic, who gave the Eternity name to our speakers. The bass sphere bronze is carefully cast in Kuzma's foundry and Vladimir Ivanovic is the designer of the speaker's appearance and the one that sculpted the bronze. He will also design our amplifiers to have a sculpted bronze top plate.


"There will also be a 'baby' omni speaker named Instinct, featuring 5 x 8" woofers, 8 x 3" mids and 4 x 70-10D ribbons, with the same sort of bronze sculpture for the woofers but smaller and with a smooth surface, still hand-sculpted but as smooth as you can hand-sculpt the clay model without machining. We should finish that for the Las Vegas CES show and unveil it there."


Paralleling transducers for a given frequency band minimizes excursion requirements (the drivers share responsibility for producing the desired SPLs) and thus increases linearity and speed; plus it drives up voltage sensitivity without involving wave guides or horns. Going for omni dispersion rather than a line source (the other method which involves paralleled drivers) also more closely approximates the theoretical point source ideal of a pulsating sphere.


"Now, the speaker is a joint project between the companies Raal and Requisite Audio of Ventura, California, both with an equal partnership in the new entity Raal-Requisite based in Ventura. This company will be separate from Raal and Requisite and handle investments, marketing, distribution and sales. The speakers will be branded Raal-Requisite, manufactured in Serbia and owned by Raal-Requisite.
Danny McKinney (right) is the founder of Requisite Audio, my partner in this.

"The other half of RAAL-Requisite is Danny 'Sage' McKinney, founder of Requisite Audio. Requisite designs and builds mastering limiters, microphone preamps and cables for the recording industry. Requisite products are in use, world-wide, by producers and engineers in the recording of countless albums. In the above photo, we're in the company of one of Sage's clients, producer Rhett Lawrence (in the middle) who is originally famous for producing the Grammy Award-winning "Vision of Love" for Mariah Carey and went on to produce Whitney Houston, Gladys Knight and many others. Incidentally, I'll be making a custom ribbon tweeter for his incredible McIntosh system in his Ford GT once we put Eternity on its feet."


"The Eternity woofers are custom Beyma units with lightweight cones, Neo magnets with saturated pole pieces and cloth surrounds. They will be driven by our 300-watt tube amp with 8 x KT88s, featuring a built-in passive components EQ. The input of the amp will be terminated by about 16-20 ohms so the main stereo amp will see a normal impedance but will have to deliver current. All that just to preserve the character of the main amp as opposed to other speakers with active woofers."

If you believe that realistic playback demands both dynamic range and dynamic reflexes, then cone surface and overall sensitivity become vital. Clearly, Raal's Eternity project would offer both, the latter achieved not with so-called high-efficiency widebanders (whose by design ultra-light moving mass often makes them fragile) but with robust drivers of average efficiencies which would be raised by multiplying them. That multiplying action -- massively paralleled with 18 midranges in a concentric array of 3 rings of six 3-inch widebanders each and a Raal-designed and -built 15-ribbon tweeter cluster -- automatically generates the desirable massive radiating area. Unlike with large electrostats, however, it's not a single motor that's struggling to control a giant stretched sail. It's many many motors, each of which is responsible for only a very small section of the aggregate 'sail'. And this sail isn't flat but close to spherical for a very different radiation pattern and room interaction.


If you believe that bass is far more than boom-boom but mandatory to recreate the recording ambience and dimensional realism, then the 5 x 15-inch woofers per channel of the Eternity speaker promise a revelation. If you believe that the amplifier/speaker interface is joined at the hip; and that low bass transients are the most challenging for any amp to reproduce; then optimized active bass is the solution. It limits the owner's job to furnishing an amplifier for the midrange and treble. So far so very good. Just exactly how it would all go together; what the performance specs would be; the cosmetics; the intricacies of an omnipolar ribbon assembly and 18-driver midrange cell - all that I would learn only over time as my departure for Belgrade approached. Team Raal still had to get closer to finalizing all necessary bits 'n' pieces for their big formal splash at the Rocky Mountain Audio Show 2008 in Denver, Colorado. And... hopefully get it all done just in the nick of time to allow me an on-site audition during the tour before this mighty challenge of an omni beast would be packed up and freighted out to the US...