WhitakerAudio J C Whitaker 20 W Stereo Audio Amplifier, Manual, Page: 167 / 194

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20 W Stereo Audio Amplifier
The differences in performance from one channel to the other are small, typically the result of
output tube matching and power output capabilities.
7.3 Thermal Considerations
Running performance measurements on the 20 W Stereo Amplifier as described here requires at
least one hour (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.
Since the shelf life of a receiving tube is essentially unlimited, it is good practice to purchase
at least one spare tube for each type used. In the case of the power output tubes, which for best
performance should be matched, a pair of tubes is recommended.
7.4 Final Touches
The 20 W Stereo Amplifier has now been completed. Remove power from the unit and carefully
place the acrylic cover over the top. Secure with the four #6 screws and flat washers provided.
Figure 7.6 Completed 20 W Stereo Amplifier.