Plinius Audio SA-250 - Manual (Page 7)

7
BIAS SWITCH
This switch on the right of the panel alters the operating bias of the amplifier. The switch operates on a
pulse system and lights the Bias LED when the amplifier is switched to Class A. In Class AB the LED is
off.
BIAS AB: BIAS AB: BIAS AB: BIAS AB: This position reduces the bias on the output stage to operate the amplifier in Class AB. This is
a bias configuration used by the majority of high fidelity amplifier designers for their products. In Class
AB your Plinius SA-250 produces very high quality sound, suitable for all occasions where ‘super critical’
listening is not a priority. The quality of performance in this mode may exceed that of many other
amplifiers so a dual benefit exists in that this facility provides the user with a much cooler operating
temperature, and a much reduced demand on electricity particularly at idle (while the amplifier is not
reproducing music). This unique feature allows you to leave the Plinius SA-250 switched ON at all times,
rendering the amplifier ready for use and requiring only a few minutes of warm-up in Class A before the
very best of the amplifier's sonic qualities may be experienced.
BIAS A BIAS A BIAS A BIAS A:::: This position provides a true Class A bias to the output stage therefore ensuring the optimum
performance of the amplifier during all listening events. Class A amplifiers run hotter than Class AB
amplifiers, hence our specially designed and distinctive heat sinks. Operating the amplifier in BIAS A
necessitates two precautions that should be observed.
1. 1. 1. 1. On switching to BIAS A, the temperature of the amplifier will quickly increase and the amplifier will
become quite hot. Once again we remind you to ensure that you have left adequate space around
the amplifier for ventilation. Ensure that no objects are resting on the amplifier and check that the
heat sink (cooling fins) are not obstructed in any way.
2. 2. 2. 2. The current required from the mains supply in BIAS A is approximately 1,000 watts, similar to a
small electric heater. The amplifier should not be connected to a wall outlet that is shared with
other heavy current appliances such as heaters or electric motors. If in doubt, check with your
Plinius dealer for advice.