Audio ICs
4. Bass boost control system
Bass boost control is as follows in Fig. 8.
BA3870
The comparator level and gain of each block are given by
the following equations.
Attenuation of ATT2:
: GATT2 = 20log
Gain of Amp E:
R13//R14
R12)R13//R14
(dB)
: GE = 20log R15)R16
R16
(dB)
Comparator level of COMP:
: VCOM = 20log ( VB S
R17 )
2
R17)R18
VB: DC voltage at BIAS OUT pin
(dBV)
If the volume output level at the beginning of control of the
low range signal system ATT1 is VBBS (dBV),
VBBS + GATT2 + GE = VCOM
In this way, bass boost control is carried out based on the
volume as shown in Fig. 9.
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