Yamaha YST-SW005 Owner's Manual

Also see for YST-SW005: Owner's manual Service manual Service manual

Contents

E-12ADVANCED YAMAHA ACTIVE SERVO TECHNOLOGYThe theory of Yamaha Active Servo Technology has beenbased upon two major factors, the Helmholtz resonator andnegative-impedance drive. Active Servo Processingspeakers reproduce the bass frequencies through an “airwoofer”, which is a port or opening in the speaker’s cabinet.This opening is used instead of, and performs the functionsof, a woofer in a conventionally designed speaker system.Thus, signals of low amplitude within the cabinet can,according to the Helmholtz resonance theory, be outputtedfrom this opening as waves of great amplitude if the size ofthe opening and the volume of the cabinet are in the correctproportion to satisfy a certain ratio.In order to accomplish this, moreover, the amplitudes withinthe cabinet must be both precise and of sufficient powerbecause these amplitudes must overcome the “load”presented by the air that exists within the cabinet.Thus it is this problem that is resolved through theemployment of a new design in which the amplifier suppliesspecial signals. If the electrical resistance of the voice coilcould be reduced to zero, the movement of the speaker unitwould become linear with respect to signal voltage. Toaccomplish this, a special negative-impedance output-driveamplifier for subtracting output impedance of the amplifier isused.By employing negative-impedance drive circuits, theamplifier is able to generate precise, low-amplitude, low-frequency waves with superior damping characteristics.These waves are then radiated from the cabinet opening ashigh-amplitude signals. The system can, therefore, byemploying the negative-impedance output drive amplifierand a speaker cabinet with the Helmholtz resonator,reproduce an extremely wide range of frequencies withamazing sound quality and less distortion.The features described above, then, are combined to be thefundamental structure of the conventional Yamaha ActiveServo Technology.Our new Active Servo Technology — Advanced YamahaActive Servo Technology — adopted Advanced NegativeImpedance Converter (ANIC) circuits, which allows theconventional negative impedance converter to dynamicallyvary in order to select an optimum value for speakerimpedance variation. With this new ANIC circuits, AdvancedYamaha Active Servo Technology can provide more stableperformance and improved sound pressure compared withthe conventional Yamaha Active Servo Technology, resultingin more natural and dynamic bass reproduction.High-amplitudebass soundCabinetPortAir woofer(Helmholtz resonator)Active ServoProcessingAmplifierSignalsSignals of low amplitudeAdvanced Negative-impedance Converter

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