7
En
The figures below show the optimum adjustment of each
control and the frequency characteristics when the
subwoofer is combined with a typical front speaker system.
■
When combined with 10 cm (4") or 13 cm (5")
acoustic suspension, 2-way system front
speakers
■
When combined with 20 cm (8") or 25 cm (10")
acoustic suspension, 2-way system front
speakers
* This diagram does not depict actual frequency
response characteristics.
In 1988, 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.
Subwoofer frequency characteristics
20
50
100
200
500Hz
40
50
60
70
80
90
dB
HIGH CUT 40 Hz
HIGH CUT 90 Hz
HIGH CUT 140 Hz
20
50
100
200
500Hz
40
50
60
70
8
0
90
dB
PHASE
Frequency response graph*
(70 Hz)
(REV)
Front
speaker
20
50
100
200
500Hz
40
50
60
70
8
0
90
dB
Frequency response graph*
PHASE
Front
speaker
(50 Hz)
(REV)
ADVANCED YAMAHA
ACTIVE SERVO TECHNOLOGY II
High-
amplitude
bass sound
Port
Cabinet
Advanced impedance
Converter
Active Servo
Processing
Amplifier
Signals of low amplitude
Air woofer
(Helmholtz resonator)
Signals
