Among all the audio components, the loudspeaker system is where there are the greater differences. We can find an extensive assortment of baffles at affordable price that deliver a great sound but, on the other hand, some models of famed brands cost in excess of US$ 50,000 a pair. We can also appreciate big differences in size: from small type baffle, that fits on a shelf, to enclosures of more than 2 meters in height, which despite hundreds of kilograms. Is there any technological justification for this diversity or is simply whim of design? A trivial answer is that to get real bass a large speaker is needed. That is effective but it seems to be more like a intuitive response than a justified one. The fact is that the principles that govern the behavior of the baffle and the electro acoustic transducers that compose it, is quite unknown to the common to the music enthusiasts, which tend to attribute ideal technical properties comparable to the remaining parts of the sound system, such as the amplifiers, CD players, equalizers, etc.
We must take into account that only a few decades ago it was unaware the behavior that would have a driver, or electro acoustic transducer, within a baffle. Magnitudes such as frequency response, cone excursion, impulse response, group delay, phase delay, were not possible to predict for the driver-baffle system and the final product was the result of long tests and experiments with different volume enclosures, ports, dampening, etc. This because until recently it had not been deducted a mathematical model for the behavior of the electro acoustic transducer within the baffle.
The dynamic loud speaker has remained virtually unchanged since its invention in 1925 by Rice and Kellogg, two engineers at General Electric Research Laboratory. The technological advances has improved its manufacturing process, the materials and the design of the cone, the power of the magnet, but the physical principle has remained unchanged: a diaphragm coupled with a coil which is within the magnetic field of a permanent magnet, oscillates due to the alternating current applied to the voice coil. This simple principle is that allow to produce sound in almost all of the baffles in the market. The electrostatic and plasma speakers, among others, are an alternative way to produce sound but, due to physical and technical limitations, they have had little market penetration.