Advanced Yamaha Active Servo Technology Ii; Qd-Bass Technology - Yamaha NS-P440 Bedienungsanleitung

Advanced Yamaha Active Servo
Technology II
In 1988, Yamaha brought to the speaker systems utilizing
YST (Yamaha Active Servo Technology) to give powerful,
high quality bass reproduction. This technology 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 cabinet capacity 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.
High-amplitude
bass sound
Signals of low amplitude

QD-BASS TECHNOLOGY

QD-BASS (Quatre Dispersion Bass) technology uses
down-firing drivers with square, pyramid-shaped
reflective plates to radiate the sound efficiently in four
horizontal directions. The reflective plates (not used in
competitors' down-firing subwoofers) negate any effects
caused by the floor surface and reduce resonance between
sound waves reflected from the floor and the unit. Also,
most other systems use circular cones, but by radiating in
four directions to avoid the legs of the cabinet, QD-BASS
reduces turbulence caused by reflection from the legs.
Changing the height of the square pyramid varies the
acoustic load, permitting relatively simple high-cut
adjustment and improved band pass properties.
The QD-BASS system provides extraordinary power and
smooth frequency response from an extremely compact
unit. It also allows greater freedom of placement, since the
sound radiates with equal effectiveness in all directions.
Air woofer
Port
(Helmholtz resonator)
Advanced Impedance
Converter
Active Servo
Processing
Amplifier
USING THE SUBWOOFER (SW-P440)
Cabinet
Signals
Pyramid-shaped
reflective plates
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