Earlier, in the seventies and eighties of the last century, it was believed that the more speakers in the column, the better. The modern approach to organizing the sound of rooms is somewhat different, the spread of the Dolby Surround system with a separate subwoofer was somewhat shaken by the confidence in the optimal sounding of speakers with several speakers, but they still have a lot of fans.
The question of what should be the speakers for the speakers, worries developers and technologists from the moment when these electromechanical emitters came into everyday life. There is a certain contradiction in the requirements for the diffuser. On the one hand, for high-quality reproduction of the lower bass spectrum, it must have a sufficiently large size and a massive magnetic coil, most of the power is spent on “bass buildup”. On the other hand, high frequencies require maximum lightness of the oscillatory system and minimal inertia.
Ultimately, the developers of acoustic accessories came to a logical decision: in the column to arrange jointly working low-frequency speakers and the so-called “tweeters”. True, in this case a “dip” was formed in the middle of the spectrum, but this problem is eliminated by the addition of a third speaker operating in this range.
The frequency response is then aligned over the entire audible band. The woofer can work without additional filters, but in order to reduce the load on it and extend its durability, it is equipped with a series-connected inductance that does not transmit medium and high waves. The middle loudspeaker is also spared the need to “wobble” on the bass and the upper components of the signal. For this, a coil and a capacitor are included in one line with it. As for the “tweeter”, only the band designed for it from about 3 kHz and higher can be fed there, for this, the capacitance is connected in series with this speaker.
Modern woofer is a complex electromechanical device. The stroke of the diffuser is quite large. To ensure it for a long time, materials are required that can withstand elastic deformations and retain their properties. Typically, the edge of the emitter is connected to the diffuser by a rubber ring of semicircular section.
A working stroke of several millimeters must have a clear path, otherwise the edges of the coil will become “rubbed” by the central magnet. It is provided with a centering washer, usually made of perforated fabric impregnated with a binder, with annular corrugation.
The woofer is a high-tech device; all the latest achievements in the field of polymer production find application in its design. The diffuser must be rigid, then the force from the coil will be transmitted to its entire surface almost instantly, and light so that the acceleration characteristic has as little delay time as possible. However, in most of the most expensive and high-quality loudspeakers, strangely enough, despite all the advances in modern technology, paper is used, as in the first dynamics, which was invented by the Americans Rice and Kellogg in 1925.
The woofer has become an integral part of the design of any high-quality speaker system.