VAC Phi "Kappa 30i" - Manual (Page 3)

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PLEASE READ CAREFULLY
Your Phi Kappa is fitted with a unique output tube monitoring circuit. Rather than directly contacting
the audio path, and thus contaminating the pure sound, the temperature of a small cathode
resistance is sensed. The four bi-color LED’s on the front panel indicate the tubes’ conditions.
If the idle current of a 300B output tube drops below nominal limits, the LED corresponding to that
tube will light green. This indicates that either the bias setting for that tube should be adjusted, or
the tube should be replaced at your convenience, but it is safe to continue operating the amplifier.
The exact idle current of each tube may be tested by means of the meter and the test switches
located on the front panel. The associated bias control should be adjusted so that the needle points
directly at the dot in the center of the meter. When no test switch is selected, the meter indicates
the incoming ac voltage (wall voltage).
Note: These LED’s will also be green when the amplifier is first switched on, and will extinguish when
the bias resistors have reached full operating temperature after approximately 30 minutes. The
threshold between green and no illumination is not precise; do not be overly concerned if some
positions take longer to extinguish. The condition of individual tubes may be checked with the built
in meter.
Note: a strong air current could cause the lights to remain green even in normal operation.
In the event that any output tube draw excessive idle current (a “run away” tube or a tube not
biased correctly), the high voltage supply in the amplifier will shut down automatically and the LED
corresponding to the problematic 300B tube will indicate red. The red light will stay on until the
power switch is turned off. This tube must be replaced. (Note: The LED’s for the other tubes will
show green after a few minutes...this should be disregarded.)
To minimize difficulties, always use genuine VAC Tested audio tubes in your Phi.
Continuous operation of this amplifier is not recommended.
Please turn off when not in use.