Yamaha YST-FSW100 Advanced Yamaha Active Servo Technology

Advanced Yamaha Active Servo Technology II

In 1998, Yamaha brought to the marketplace speaker systems utilizing YST ( Yamaha Active Servo Technology ) to give powerful, high quality bass reproduction. This technique uses a direct connection between the ampliﬁer and speaker, allowing accurate signal transmission and precise speaker control.

As this technology uses speaker units controlled by the negative impedance drive of the ampliﬁer and resonance generated between the speaker cabinet volume and port, it creates more resonant energy (the “air woofer” concept) than the standard bass

reﬂex method. This allows for bass reproduction from much smaller cabinets than was previously possible.

Yamaha’s newly developed Advanced YST II adds many reﬁnements to Yamaha Active Servo Technology, allowing better control of the forces driving the ampliﬁer and speaker. From the ampliﬁer’s point of view, the speaker impedance changes depending on the sound frequency. Yamaha developed a new circuit design combining negative-impedance and constant-current drives, which provides a more stable performance and clear bass reproduction without any murkiness.

	Cabinet		Air woofer
	Cabinet		(Helmholtz resonator)
High-amplitude
	Port

bass sound
bass sound		Advanced impedance
		Advanced impedance
		Converter

Active Servo		Signals
Processing		Signals
Processing
Ampliﬁer

Signals of low amplitude