19
EMX620
3.
Power Amplifier Part
3-1 Setting Conditions
Setting conditions are as follows unless otherwise specified.
Input Terminal:
INPUT CH 5 LINE 1
Measuring Output Terminal:
SPEAKERS A
Output Load:
4 ohm (more than 200 W)
Connect the resistor when inspecting the power amplifier section.
INPUT CH1-CH6
MONITOR level control:
Minimum
EFFECT level control:
Minimum
LEVEL level control:
Minimum
Note: Other control settings are the same as the mixer part in section 2-3.
3-2 Power ON Muting
The muting relay should be released 2.5 +/- 1 seconds after the power switch is turned on.
3-3 Speaker Terminal DC Voltage
When input terminals are grounded, confirm that each output terminal voltage is 0 +/- 100 mV.
3-4 Gain
When applying a 1 kHz -26.0 dBs sine wave to an INPUT terminal, confirm that the SPEAKER A and MONITOR terminal output
level is +20 +/- 2.0 dBs.
The SPEAKER B output terminal should be measured.
3-5 Frequency Response
Apply a 20 Hz, 1 kHz and 20 kHz = 26 dB sine wave signal separately to the input; the output level should be between -3 and +1dB
at 20 Hz and 20 kHz, when 1 kHz is set as the reference.
3-6 Harmonic Distortion
Apply a 1kHz sine wave signal to the input; the three output level should be 200 W/4 ohms (31.2 dBs/ch); the distortion ratio should
be less then 0.5 %.
Apply a sine wave signal of 20Hz, 1kHz and 20 kHz separately to the input; the three output level should be 100 w/4 ohms (28.2 dBs/
ch); the distortion ratio should be less than 0.5 %.
Do this inspection within 30 seconds.
Note: Apply a DIN-LOW PASS filter.
Apply a 10 kHz -26 dBs rectangular signal to the input and connect a capacitor (10 pF to 0.47
µ
F) parallel to the 4 ohm load resistor,
µ
H to 0.47 H) serial to the 4 ohm load resistor. Confirm that the output signal is as illustrated below.
Overshoot:
Vp / Vo <= 1.8
Ringing:
5waves and less than 5 waves
Next, only connect a capacitor (10 pF to 0.47
µ
F) to the SPEAKERS terminal as a load, and confirm that the output is as follows:
Overshoot:
Vp / Vo <= 2.5
Ringing: It should end within 7 waves; there is no oscillation.
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