Macro-Tech 24x6 Reference Manual - 4 Operation
Page 17
Macro-Tech 24x6 & 36x12 Power Amplifiers
4 Operation
4.1 Precautions
Macro-Tech amplifiers are protected from internal and
external faults, but you should take the following pre-
cautions for optimum performance and safety:
1. WARNING: Never strap the outputs together
for Parallel-Mono operation! Never bridge the
outputs for Bridge-Mono operation!
The
Macro-Tech 24x6 and 36x12 cannot be used in
any mono mode.
2. Turn off the amplifier and unplug it from the
AC mains
before removing a
P.I.P. card.
2. Use care when making connections, selecting
signal sources and controlling the output level.
The load you save may be your own.
3. Do not short the ground lead of an output cable
to the input signal ground. This may form a
ground loop and cause oscillations.
4. Operate the amplifier from AC mains of not
more than 10% variation above or below the se-
lected line voltage and only the specified line
frequency.
5. Never connect the output to a power supply
output, battery or power main.
Such connec-
tions may result in electrical shock.
6. Tampering with the circuitry by unqualified per-
sonnel or unauthorized circuit changes invali-
dates the warranty.
Remember: Crown is not liable for any damage result-
ing from overdriving other components in your system.
4.2 Indicators
The front panel has several helpful indicator LEDs.
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 sys-
tem are working. It does not indicate the status of the
high voltage supplies. For example, the Enable indica-
tor 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 4.3).
The amber
ODEP indicators
confirm the normal op-
eration of Crown’s patented Output Device Emulation
Protection circuitry. During normal operation, they glow
brightly to show the presence of reserve thermal-dy-
namic energy. They dim proportionally as the energy
reserve decreases. In the rare event that there is no
reserve, the indicators turn off and
ODEP proportion-
LEVEL
LEVEL
ON
OFF
30
27
24
21
18
15
12
9
6
3
0
ENABLE
ODEP
30
27
24
21
9
6
3
0
SIGNAL / IOC
18
15
12
CH1
CH2
(3600)
(1200)
ally limits the drive level of the output stages so the
amplifier can continue safe operation even when con-
ditions are severe. (For a more detailed description of
ODEP, see Section 4.3.1.)
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 activates its thermal protection
circuitry (see Section 4.3.2). 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 signal pres-
ence, distortion and input overload. As signal presence
indicators, they flash with normal intensity in sync with
the output audio signals. As
IOC (Input/Output Com-
parator) indicators, they flash brightly if there is any
difference between the input and output signal wave-
forms greater than 0.05%. Because transient distor-
tion 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 perfor-
mance. As input overload indicators, they flash brightly
with a 0.5 second hold delay to show that an input sig-
nal is too large and must be clipped at the input.
Under abnormal conditions where one of the ampli-
fier’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 4.2 shows the possible states for
the
ODEP and Signal/IOC indicators. It also describes
the conditions that may be associated with the differ-
ent 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 important to note the
possible states of the indicators in the rare event that
you experience a problem. This can greatly aid in de-
termining the source of problems. Please contact your
local Crown representative or our Technical Support
Group for further assistance.
Fig. 4.1 Indicators