Fig. 2 F660 Rear Panel
Operations:
After turning on the MAINS SWITCH on the rear panel, the unit performs a self test and after
successful completion you will see the following screen:
At this point the unit is in stand-by mode and the audio circuitry and the tubes are still powered-off,
the unit is in bypass mode, but the output meter is connected to the main output. This allows the
user to measure the level even in bypass mode.
To turn the F660 on, please push the rotary control. The F660 will power up and go through a tube
calibration cycle. During this cycle you will see the anode currents in both halves of the push-pull
Class A amplifier.
Fredenstein F660 Manual Release 2.1 July 18, 2014 Page 2
