YMU757B Datasheet, PDF (32/43 Pages) YAMAHA CORPORATION – MA-1C

YMU757B
Sound quality correction circuit
It is possible to correct the sound quality and gain by using an external circuit connected to EQ1 to 3 terminals.
A circuit structure of EQ1 to 3 terminal inside and example of external circuit are as follows.
C3 Rx
AIN
C1 R1
EQ1
EQ2
C2
R2
EQ3
FM
VOL
+
VREF
Gain and filter characteristic are adjusted by value of C1, C2, R1 and R2.
Gain = R2 / R1. Recommendation of R1 is 22kΩ and R2 is 82kΩ (gain = 3.7 times).
Cut off frequency f1 and f2 of filter is as follows.
f1=1/ (2π×R1×C1).
f2=1/ (2π×R2×C2).
Recommendation of each value are as follows.
If C1=0.022µF and C2=120pF, cut off frequency f1=330Hz and f2=16kHz.
Gain
Gain1
Gain1 -3dB
f1
Freq
f2
Moreover, the circuit enclosed with the dotted line becomes necessary when an analog signal is inputted from AIN and it
wants to mix it.
The level adjustment that it is mixed depends on the resistance ratio R2/Rx of Rx and R2.
The value of Rx when it wants to mix it in the amplitude of one time of AIN is 82kΩ.
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