Crown International, Inc.
P.O. Box 1000
Elkhart, IN 46515-1000
TEL: 574-294-8200
FAX: 574-294-8FAX
www.crownaudio.com
CL2
11/02
131516-2
For more details refer to the applicable Reference Manual or
Contact Crown Audio Technical Support. The provided data
should not be construed as specifications.
Crown is a registered trademark of Crown International, Inc.
Printed in U.S.A.
© 2002 Crown Audio, Inc.
AC Power Draw and Thermal Dissipation
C O N T R A C T O R S E R I E S
This document provides detailed information about the amount of power
and current drawn from the AC mains by the
CL2
amplifier and the
amount of heat produced under various conditions. The calculations pre-
sented here are intended to provide a realistic and reliable depiction of
the amplifier. The following assumptions or approximations were made:
• The amplifier’s available channels are loaded and full power is being
delivered.
• The amplifier efficiency at standard 1-kHz power is estimated to be
65%.
• Quiescent power draw is approximately 60 watts.
• When running at full speed, typical power draw for the internal fan
is 12 watts or less.
• 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%.
Here are the equations used to calculate the data presented in Figure 1:
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
dissipation:
The value used for inefficiency is 0.35 (1.00–0.65). 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:
Figure 1 Power Draw, Current Draw and Thermal Dissipation at Various Duty Cycles
CL2
LOAD
Duty
Cycle
Current Draw(Amps) Thermal Dissipation
Thermal Dissipation
Thermal Dissipation
Current Draw(Amps)
Current Draw(Amps)
AC Mains
Power
Draw
(Watts)
AC Mains
Power
Draw
(Watts)
AC Mains
Power
Draw
(Watts)
100-120 230-240 btu/hr kcal/hr
100-120 230-240 btu/hr kcal/hr
100-120 230-240 btu/hr kcal/hr
50%
40%
30%
20%
10%
8 OHMS DUAL / 16 OHMS BRIDGE
4 OHMS DUAL / 8 OHMS BRIDGE
296
1419
5.4
10.8
1075
260
1175
4.4
8.8
872
235
993
3.4
6.7
669
174
690
2.4
4.7
466
113
448
1.3
2.6
263
237
2 OHMS DUAL / 4 OHMS BRIDGE
142
563
1.8
3.6
360
232
922
3.3
6.6
660
323
1281
4.8
9.6
960
413
1639
6.3
12.6
1260
504
1998
7.8
15.6
1560
940
3.4
6.7
675
200
793
2.8
5.5
552
163
646
2.2
4.3
429
126
499
1.6
3.1
306
89
352
1.4
1.8
183
