Advanced Yamaha Active Servo Technology - Yamaha HTR-5750 Owner's Manual

ADVANCED YAMAHA ACTIVE SERVO TECHNOLOGY
The theory of Yamaha Active Servo Technology has been
based upon two major factors, the Helmholtz resonator
and
negative -
impedance 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 at 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 outputted
from
this opening as waves of great amplitude if 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 new design in which the amplifier supplies
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. 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.
These waves are then radiated from the cabinet opening as
high-amplitude 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 conventional Yamaha Active
Servo Technology.
Our
new Active Servo Technology —
Advanced Yamaha
Active Servo Technology
— adopted Advanced Negative
Impedance Converter (ANIC) circuits, which allows the
conventional negative impedance converter to
dynamically
vary in order to select an optimum value for speaker
i
mpedance variation. With this new ANIC
circuits, Advanced
Yamaha Active Servo Technology can
provide more stable
performance and improved sound
pressure compared with
the
conventional Yamaha Active Servo Technology, resulting
in more natural and
dynamic bass reproduction.
High-amplitude
• -
bass sound
Cabinet
LL
Air woofer
Port (Helmholtz resonator)
Advanced Negative-
impedance Converter
(C(
Active Servo
Processing -4—
411i
Amplifier
Signals
/
Signals of low amplitude
E-9