Another unique capability of Samsung's Audio Lab is its simulation system, which allows engineers to create virtual prototypes and test them using a computer. The software lets engineers define a problem, then specify the underlying physics. For a simulation to be manageable, you need to define the objective narrowly and precisely, notes Senior Mechanical Engineer Andri Bezzola.
In his presentation, Dr. Bezzola described two simulations that were used in the design of the Radiant-360 speakers. The R6 and R7 are both elliptically shaped, and look like oversize lava lamps. Both are active designs, with a dedicated digital amplifier for each driver, and employ digital signal processing to smoothen response. As the model designation implies, the goal was to create a speaker that provides even frequency response in all directions, not just horizontally, but vertically as well.
Conventional speakers are omnidirectional at lower frequencies, where the wavelengths are much larger than the size of the driver. But at higher frequencies, as wavelengths get shorter, speakers become more directional. "At low frequencies, a loudspeaker spreads sound like a light bulb spreads light," Devantier explains. "At high frequencies, it's like a flashlight. We wanted to make the Radiant-360 behave like a light bulb at all frequencies."
Hence the unusual shape. Instead of outward-firing woofers and tweeters, Radiant-360 speakers employ an upward-firing tweeter mated to a downward-firing woofer that radiates sound through a slot halfway-up the enclosure. Samsung calls the unusual woofer configuration a "ring radiator."
The unusual design posed some mechanical challenges. What is the best size and shape for the slot through which the woofer vents into the room? Is it possible to achieve smooth response from such a design? And what is the best way to obtain smooth omnidirectional response from the upward-firing tweeter? Should it radiate unhindered, or should there be some kind of structure in front to redirect energy? Answering those questions could have involved a long cycle of prototyping and testing, repeated many times until satisfactory designs were determined.
Instead, Bezzola created computer simulations to test several virtual prototypes, working through the day to define the problem, and then letting the computer run the simulation overnight.
In one simulation, he examined the velocity of air particles inside the woofer slot's cavity, comparing designs with a straight-edged slot to others with slots that curve gently inward and outward. After the first set of simulations, Bezzola honed in on the most promising results, then ran another set of more finely granulated simulations. In the end, Samsung opted for a curved slot with 13.5mm radius.
In another test, Bezzola ran 42 different simulations to see how different types of wave guides in front of the tweeter would affect high-frequency behaviour. In the end, Samsung opted for a phase plug, as it provided the desired omnidirectional output, both vertically and horizontally.
These simulations don't lead directly to a finished design, Bezzola emphasizes. "We still need to make physical samples. But this cuts down on the number of physical prototypes we have to have made."
And that speeds up development process significantly, Devantier says. "I really believe we're on the forefront here. This is the same kind of analysis that makes cars lighter and safer."