WhitakerAudio 60 W Stereo Power Amplifier, Руководство пользователя и по сборке

Страница: 109 / 154

109
60 W Stereo Power Amplifier
for minimum distortion reading. Power output should not change significantly when R20
is adjusted.
• Change the input signal to 30 Hz (0.9 V rms) and measure THD. Adjust the Balance
control again for minimum distortion. The optimal setting should roughly coincide for
each frequency. In the event that the optimal settings for 30 Hz and 1 kHz do not coincide,
split the difference between the two settings.
The oscilloscope method is useful for initial setup. The distortion analyzer approach is
typically more sensitive and should ideally be performed after the oscilloscope check.
Adjustment of the drive voltage balance may influence the optimal bias setting for the output
tubes. It is recommended that the bias adjustment steps outlined previously be repeated after the
drive balance procedure.
7.8 Recorded Performance
It is recommended that the performance of each channel be recorded for future reference. Table
7.2 is provided for that purpose.
Table 7.2 Measured Performance of the 60 W Stereo Power Amplifier
Conditions Parameter Right Channel Left Channel
Measurements taken at 1 W
power output
(2.8 V rms) Input voltage 0.15 V rms 0.15 V rms
Frequency response, ±1 dB
THD
IMD (@ 2.3 V rms output)
Noise unweighted, shorted
input terminals
Measurements taken at 5 W
power output
(6.3 V rms) Input voltage 0.32 V rms 0.32 V rms
Frequency response, ±1 dB
THD
IMD (@ 5.1 V rms output)
Noise, unweighted, shorted
input terminals
Measurements taken at 10 W
power output
(8.9 V rms) Input voltage 0.46 V rms 0.46 V rms
Frequency response, ±1 dB
THD
IMD (@7.2 V rms output)
Noise, unweighted, shorted
input terminals