Celebrating 20-years, Amina Technologies, a manufacturer of invisible speakers has released a white paper that discusses its Distributed Mode Loudspeaker (DML) design.
According to Amina Technologies, its technologies are based on Bending Wave Theory, which is a principle workings of soundboards within instruments, like the strings of a guitar, violin or piano transferring the vibration via a bridge to the soundboard, which in turn projects the sound into the room, radiating evenly in all directions.
With DML, the company’s patented electronic neodymium exciters set in motion tens to thousands of tiny sympathetic vibrations all over a planar soundboard. The vibrations excite adjacent air molecules which come together with Amina’s tuning and Opti-drive and Opti-damping techniques to create full-bodied, omni-directional sound, just like the instrument, filling the room evenly, corner to corner. This ‘spread-source’ technology differs greatly from cone-driven loudspeakers which are ‘point-source’ technology.
So how does an AV integrator determine when to opt for spread-source versus point-source? Amina Technologies worldwide vice president of engineering technologies and VP of sales for the Americas Keith Vanderkley asserts that its helpful to first understand these two properties and how they behave under the laws of physics that govern sound.
“The laws don’t change – they apply to all forms of sound. It’s the way the sound is produced that changes the playing field,” states Vanderkley.
“Think of standing in a room with a piano being played versus a recording of that piano in a room. The two are experienced completely differently, because the sound is produced through different mediums.”
He continues that all speakers start from the same basic level.
“All loudspeakers are transducers, converting an AC voltage into an analogue acoustic pressure wave that oscillates above and below constant atmospheric pressure, ultimately moving the eardrum in our ears, which causes us to hear sound. It’s what happens in-between the two actions that determine how we hear that sound – anywhere from close to original to outside of critical distance, which is unintelligible,” boasts Vanderkley.
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“Reflections created by objects, walls, floors, ceilings play a huge role as to how we perceive sound. There is so much that comes into play, that it would take a volume of books to explain,” he continued. “The most important objective in sound is to have the listener experience it as close as possible to the original and maintain its intelligibility.”
“Traditional speakers (point-source) create a phase dependent wave, converting an AC voltage (phase) into an analogue wave of positive and negative pressure (phase) emanating from one point in time, in space. Reflections that bounce off walls and ceilings arrive back having travelled different distances, and their phase relationship might not be the same as the original, adding both constructively and destructively to the direct soundwave. This colours the sound, compromising sound quality and intelligibility, especially in mid and far field, where the listener is further away. Additionally, point-source speakers develop the amplitude at the centre of the cone, losing 6 dB of acoustic power per doubling of distance as it propagates without reflections in the near field.”