This document provides detailed information about the amount of power
and current drawn from the AC mains by the Crown
the amount of heat produced under various conditions. The calculations
presented here are intended to provide a realistic and reliable depiction
of the amplifiers. The following assumptions or approximations were
• The ampliﬁ er's available channels are loaded, and full power is being
• Efﬁ ciency at standard 1 kHz power into 4 ohms is 61.0%.
• Quiescent power draw is 36.0 W.
• The estimated duty cycles take into account the typical crest factor for
each type of source material.
• Duty cycle of pink noise is 50%.
• Duty cycle of highly compressed rock 'n' roll midrange is 40%.
• Duty cycle of rock 'n' roll is 30%.
• Duty cycle of background music is 20%.
• Duty cycle of continuous speech is 10%.
• Duty cycle of infrequent, short duration paging is 1%.
Figure 1 Power Draw, Current Draw and Thermal Dissipation at Various Duty Cycles
S E R I E S
AC Power Draw and Thermal Dissipation
Here are the equations used to calculate the data presented in Figure 1:
Xs500 ampliﬁ er and
The quiescent power draw of 36.0 watts is a maximum value and includes
power drawn by the fan. The following equation converts power draw in
watts to current draw in amperes:
The value used for Power Factor is 0.83. The Power Factor variable is
needed to compensate for the difference in phase between the AC mains
voltage and current. The following equation is used to calculate thermal
The value used for inefﬁ ciency is 0.39 (1.00–0.61). The factor 3.415
converts watts to btu/hr. Thermal dissipation in btu is divided by the
constant 3.968 to get kcal. If you plan to measure output power under
real-world conditions, the following equation may also be helpful:
Crown International, Inc.
P .O. Box 1000
Elkhart, IN 46515-1000
For more details refer to the applicable Operation Manual or
contact Crown Factory Service. The provided data should not be
construed as speciﬁ cations.
Crown and Crown Audio are registered trademarks of Crown
International, Inc. Printed in U.S.A.
© 2004 Crown Audio