Nexo NXAMP 4X4, Service Manual

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4-7. Channel separation
1) Ground the channel 2, channel 3 and channel 4 input terminals via a 600 Ω resistor.
Input the 1 kHz, 0 dBu sine wave to the channel 1 input terminal and measure the output voltage obtained at the
channel 1 output terminal as the reference voltage (0 dB).
Confirm that the output voltage at the channel 2, channel 3 and channel 4 output terminals is -65 dB or less as
compared with the reference voltage.
2) Ground the channel 1, channel 3 and channel 4 input terminals via a 600 Ω resistor.
Input the 1 kHz, 0 dBu sine wave to the channel 2 input terminal and measure the output voltage obtained at the
channel 2 output terminal as the reference voltage (0 dB).
Confirm that the output voltage at the channel 1, channel 3 and channel 4 output terminals is -65 dB or less as
compared with the reference voltage.
3) Ground the channel 1, channel 2 and channel 4 input terminals via a 600 Ω resistor.
Input the 1 kHz, 0 dBu sine wave to the channel 3 input terminal and measure the output voltage obtained at the
channel 3 output terminal as the reference voltage (0 dB).
Confirm that the output voltage at the channel 1, channel 2 and channel 4 output terminals is -65 dB or less as
compared with the reference voltage.
4) Ground the channel 1, channel 2 and channel 3 input terminals via a 600 Ω resistor.
Input the 1 kHz, 0 dBu sine wave to the channel 4 input terminal and measure the output voltage obtained at the
channel 4 output terminal as the reference voltage (0 dB).
Confirm that the output voltage at the channel 1, channel 2 and channel 3 output terminals is -65 dB or less as
compared with the reference voltage.
Note: Measure the output level with the 22 Hz-22 kHz band pass filter specified at 1-3.
4-8. Output noise level
With each input terminal grounded via a 600 Ω resistor, measure the noise level at each output terminal and confirm that
the measured value is -56 dBu or less.
Note: Measure the noise level with the 22 Hz-22 kHz band pass filter specified at 1-3.
4-9. Stability
With no load resistors connected to all output terminals, input the 1 kHz, +2.0 dBu square wave to all input terminals and
measure the primary power consumption (Wno_load).
With the 0.1 uF capacitor connected to all output terminals, input the 1 kHz, +2.0 dBu square wave to all input terminals
and measure the primary power consumption (Wcap_load).
Confirm that the following equation is satisfied.
Wcap_load-Wno_load = 60 W or less
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