Crown Studio Reference I, SR-I Supplementary Manual
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SR-I
S T U D I O R E F E R E N C E S E R I ES
AC Power Draw and Thermal Dissipation
The information provided on this page is calculated data based on driving both channels to rated output using the 1 kHz Maximum Average
Power rating method.
Other parameters used in calculation include a conservative idle current
estimate of 90 watts and a conservative estimate of effeciency at 65%.
Information is provided only for getting an idea of current draw and heat
produced. Actual performance will vary depending on environment, program material, load, signal, and AC mains voltage and frequency.
Values of calculated current draw are intended to represent average draw
corresponding to the thermal breaker requriements that should be met to
handle the amplifier as a load on the AC mains.
Peak current draw with dynamic program material may be significantly
higher. Thermal information is provided to assist with calculating air
conditioning needs. The data here should not be construed as specifications.
Duty cycle of various program material:
Individual speech: 10%
Acoustic/chamber music: 20%
Full-range rock music: 30%
Compressed rock music: 40%
Pink noise: 50%
Here are the equations used to calculate the data presented in Figure 1:
AC Mains Power
Draw (watts)
Total output power with all
channels driven (watts)
=
Amplifier Efficiency (.65)
x
Duty
Cycle
Quiescent Power
+
Draw (watts)
The quiescent power draw is a maximum value and includes power drawn by the fan. The
following equation converts power draw in watts to current draw in amperes:
AC Mains Power
Current Draw
(amperes)
=
AC Mains
Volta
Draw (watts)
x
e
Factor (.83
Power
The value used for Power Factor is 0.83. The Power Factor variable is needed to compensate for the differnece in phase between the AC mains voltage and current. The following
equation is used to calculate thermal dissipation:
Thermal
Dissipation
=
(btu/hr)
Total output power with all
channels driven (watts)
Amplifier Efficiency (.65)
Duty
x
Cycle
.35
x
Quiescent Power
+
Draw (watts)
x
3.415
The value used for inefficiency is 1.00-efficiency. 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:
Thermal
Dissipation
(btu/hr)
Total measured output power
from all channels (watts)
=
Amplifier Efficienc
(.65)
.35
x
Quiescent Power
+
Draw (watts)
x
3.415
Studio Reference I
LOAD
2 Ohm Stereo / 4 Ohm Bridge 4 Ohm Stereo / 8 Ohm Bridge / 2 Ohm Parallel Mono 8 Ohm stereo / 16 Ohm Bridge / 4 Ohm Parallel Mono
Duty
Cycle
AC
Mains
Power
Draw
(watts)
Current Draw
(Amps)
120V 230V btu/hr kcal/hr 120V 230V btu/hr kcal/hr 120V 230V btu/hr kcal/hr
Thermal
Dissipation
50% 1874 19.3 9.7 2500 630 1290 13.3 6.7 1780 449
40% 1518 15.6 7.8 2060 519 1050 9.3 5.4 1485 374
30% 1161 11.9 6.0 1620 408 557 8.3 4.2 1190 300
20% 804 8.3 4.1 1185 299 570 5.9 2.9 900 227
10% 447 4.6 2.3 745 188 330 3.4 1.7 605 152
A Harman International Company
Crown International, Inc.
1718 W. Mishawaka Rd.
Elkhart, IN 46517-9439
TEL: 574-294-8200
FAX: 574-294-8FAX
www.crownaudio.com
AC
Mains
Power
Draw
(watts)
Current Draw
(Amps)
Thermal
Dissipation
For more details refer to the applicable Operation
Manual or contact Crown Factory Service. The
provided data should not be construed as specifciations.
Crown and Crown Audio® are registered trademarks of Cown international, Inc. Printed in
U.S.A.
©2005 Crown Audio, Inc.
04/05 138354-1
AC
Mains
Power
Draw
(watts)
Current Draw
(Amps)
Thermal
Dissipation
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