LA4165M
No. 2824-8/16
Continued from preceding page.
C12 : (4.7
F)
Together with series resistor R8, determines the preamp low-frequency cut-off. For C12 = 4.7
F and R8 = 100,
the cut-off is approximately 200Hz. The cut-off can be set to approximately 100 or 300Hz by giving C12 a value
of 10
F or 2.2F, respectively.
C13 : (0.47
F)
Preamp input coupling capacitor.
C14 : (2200
pF)
EMI suppression capacitor. Select this according to the characteristics of the record/play head.
C15 : (3300pF)
Microphone input high-frequency filter.
C16 : (220
F)
Reference voltage decoupling capacitor.
C17 : (220
F)
Head DC supply ripple filter.
C18 : (220
F)
Supply decoupling capacitor.
C19 : (1 to 10
F)
Reference resistor (R7) bypass capacitor. Setting should be performed according to motor characteristics.
C20 : (1
F)
Load (motor) bypass capacitor. Setting should be performed according to motor characteristics.
R1 : (5 to 15k
)
Determines the flow of AC current through the head. Select this according to the head characteristics and
ALC level.
R2 : (820
)
Determines the microphone input level at which the voice sensor starts operating when VR1 is at minimum.
Larger values for R2 give voice sensor operation at lower microphone input signal levels.
R3 : (3k
)
Improves high-frequency response and reduces high-frequency distortion. Distortion above 5kHz increases as
R3 decreases.
R4 : (100k
to 3M)
Determines ALC recovery time.
R5 : (300k
)
Voice sensor circuit control current resistor. R5 and C11 form the motor drive hold-time constant.
R6 : (20 to 70k
)
Determines motor speed. Select this according to the motor characteristics and the value of variable resistor
VR2.
R7 : (100 to 300
)
Select this according to the motor characteristics.
R8 : (0 to 200
)
Preamp negative feedback resistor.
R9 : (3.9k
)
Bias set resistor for electrostatic microphones.
The current into or out of the reference voltage pin (pin 21) should not be greater than
±1mA, or the biase of
other circuits will be affected. In particular, the power amplifier output power will be reduced.
Continued on next page.