WhitakerAudio JC Whitaker 20 W Stereo Integrated Audio Amplifier, Manual

Page: 171 / 196

171
20 W Stereo Integrated Audio Amplifier
7.3 Reference Measurements
It is recommended that the performance of each channel be recorded for future reference. Table
7.4 is provided for that purpose. Use the following settings:
• Set the Input switch on the front panel to Line Input.
• Set the Balance control to center travel.
• Set the Bass and Treble controls to flat response.
• Volume control fully clockwise.
7.4 Thermal Considerations
Running performance measurements on the 20 W Stereo Integrated Amplifier as described here
requires at least two hours (when using manual test equipment), during which time the typical
heating pattern for this unit can be observed. It will be noted that all transformers except for the
power transformer run at essentially room temperature. The power transformer runs warm, but
not too hot to touch. The vacuum tubes are, of course, quite hot and are capable of inflicting burns
on the skin. No other areas of the amplifier should run hot.
Table 7.4 Measured Performance of the 20 W Stereo Integrated Amplifier
Conditions Parameter Right Channel Left Channel
Measurements taken at 1 W
power output (2.8 V rms)
Input voltage 0.30 V rms 0.30 V rms
Frequency response
THD
IMD (at 2.3 V rms output)
Noise unweighted, shorted
input terminals
Measurements taken at 5 W
power output (6.3 V rms)
Input voltage 0.80 V rms 0.8 V rms
Frequency response
THD
IMD (at 5.1 V rms output)
Noise, unweighted, shorted
input terminals
Measurements taken at 10 W
power output (8.9 V rms)
Input voltage 1.1 V rms 1.1 V rms
Frequency response
THD
IMD (at 7.2 V rms output)
Noise, unweighted, shorted
input terminals