Crown Audio MA-36X12 ユーザーズマニュアル

The front panel has several helpful indicator 
LEDs  (Figure 5.1).

The amber Enable indicator is provided to 
show the amplifier has been turned on (or 
enabled) and that its low voltage power supply 
and forced-air cooling system are working. It 
does not indicate the status of the high voltage 
supplies. For example, the Enable indicator will 
remain lit during unusual conditions that would 
cause the amplifier’s protection systems to put 
a high-voltage supply in “standby” mode (see 
Section 4.1.3).

The amber ODEP indicators confirm the nor-
mal operation of Crown’s patented Output 
Device Emulation Protection circuitry. During 
normal operation, they glow brightly to show 
the presence of reserve thermal-dynamic 
energy. They dim proportionally as the energy 
reserve decreases. In the rare event that there is 
no reserve, the indicators turn off and ODEP 
proportionally limits the drive level of the out-
put stages so the amplifier can continue safe 

operation even when conditions are severe. 
(For a more detailed description of ODEP, see 
Section 4.1.1).

The ODEP indicator for the affected channel will 
turn off if a high-voltage power supply is put in 
“standby” mode, a high-voltage power supply 
fuse (or breaker) blows, or a transformer acti-
vates its thermal protection circuitry (see Sec-
tion 4.1.4). Both ODEP indicators turn off if the 
amplifier loses AC power, the power switch is 
turned off or the low-voltage power supply fuse 
blows.

The green Signal/IOC indicators show sig-
nal presence, distortion and input overload. As 
signal presence indicators, they flash with nor-
mal intensity in sync with the output audio sig-
nals. As IOC (Input/Output Comparator) 
indicators, they flash brightly if there is any dif-
ference between the input and output signal 
waveforms greater than 0.05%. Because tran-
sient distortion happens quickly, a 0.1 second 
“hold delay” keeps the indicators on long 
enough to be easily noticed. The IOC function 
provides proof of distortion-free performance. 

As input overload indicators, they flash brightly 
with a 0.5 second hold delay to show that an 
input signal is too large and must be clipped at 
the input.

Under conditions where one of the amplifier’s 
high-voltage power supplies is temporarily put 
in standby mode, the Signal/IOC indicators will 
stay on with full brightness. They will resume 
normal operation when the amplifier is no 
longer in standby mode.

The table in Figure 5.2 shows the possible 
states for the ODEP and Signal/IOC indicators. 
It also describes the conditions that may be 
associated with the different indicator states. 
The Enable indicator will be off with the first 
indicator state, “There is no power to the ampli-
fier.” All other conditions in the table will occur 
with the Enable indicator turned on. It is impor-
tant to note the possible states of the indicators 
in the rare event that you experience a problem. 
This can greatly aid in determining the source 
of problems. Please contact your local Crown 
representative or our Technical Support Group 
for further assistance.