Yamaha SW-3 Owner's Manual - Page 12
ACTIVE SERVO TECHNOLOGY, REMOVING THE FRONT GRILLE, Active Servo Processing speakers
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ACTIVE SERVO TECHNOLOGY The theory of Active Servo Technology is based upon two major factors, the Helmholtz resonator and negativeimpedance drive. Active Servo Processing speakers reproduce the bass frequencies through an "air woofer", which is a port or opening in the speaker's cabinet. This opening is used instead of, and performs the functions of, a woofer in a conventionally designed speaker system. Thus, signals of low amplitude within the cabinet can, according to the Helmholtz resonance theory, be output from this opening as waves of great amplitude if the design is such that the size of the opening and the volume of the cabinet are in the correct proportion to satisfy a certain ratio. In order to accomplish this, moreover, the amplitudes within the cabinet must be both precise and of sufficient power because these amplitudes must overcome the "load" presented by the air that exists within the cabinet. Thus it is this problem that is resolved through the employment of a design in which the amplifier functions to supply special signals. If the electrical resistance of the voice coil could be reduced to zero, the movement of the speaker unit would become linear with respect to signal voltage, and, to accomplish this, a special negative-impedance output-drive amplifier for subtracting output impedance of the amplifier is used. By employing negative-impedance drive circuits, the amplifier is able to generate precise, low-amplitude low-frequency waves with superior damping characteristics, and these waves are then radiated from the cabinet opening as highamplitude signals. The system can, therefore, by employing the negative-impedance output drive amplifier and a speaker cabinet with the Helmholtz resonator, reproduce an extremely wide range of frequencies with amazing sound quality and less distortion. The features described above, then, are combined to be the fundamental structure of the Active Servo Technology. Highamplitude bass sound Cabinet Port Air woofer (Helmholtz resonator) Active Servo Processing Amplifier Signals Negative-impedance Signals of low amplitude output drive REMOVING THE FRONT GRILLE The front grille is fastened to the enclosure at four points, and can be removed if desired. To remove the grille, first hold the bottom of the grille and unfasten the lower part of the grille by pulling it gently, and then hold both sides of the grille and slowly pull straight away from the speaker. To reattach, line up the four pegs on the inside surface of the grille with the four corresponding holes on the speaker and push gently. Note When the grille is removed, take care not to touch the speaker unit with your hands or to exert excessive force with tools. 12