The Singing Machine SML418BK Instruction Manual page 14

Operation
Using the LINE IN Jack (Continued)
W
6
Adjust the MIC VOLUME 1 or 2
control as desired. Increasing this
will increase the volume of the
respective microphone.
7
Rotate the ECHO control to add an
echo effect to your voice. Rotate
towards MAX to increase the echo
effect.
V
8
Press the power ON/OFF button
U
to turn the unit off.
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