Technology Brief Protection Features Explained

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Technology Brief: Class TD, Regulated SMPS (R.SMPS™), and Intercooler®
LAB GRUPPEN ampliers. However, musical transients last only a
fraction of a second. Continuous very high frequency content does
not exist in normal program material, and is potentially damaging to
connected high frequency drivers. All C Series ampliers include a
sophisticated VHF detection circuit that effectively discriminates
between musical content and spurious signals. The circuit’s
operational area factors in output power, frequency and duration.
Detection begins at about 10 kHz for maximum peak power, and
continues at a -6 dB slope. The higher the frequency, the lower
the power level for detection. The attack time for implementing
protection decreases at higher frequencies, allowing some sustained
activity at 10 kHz but acting very rapidly above 20 kHz. The VHF
protection has no limiting function; all signals are passed at full power
with no effect on transient material. However, should dangerous
VHF content be detected, the output will mute for six seconds; if no
further VHF content is detected, the output automatically un-mutes.
Simultaneously, a fault condition is shown on a front panel LED
and transmitted via NomadLink for indication on the DeviceControl
software GUI.
Benefits: Protection of connected high frequency drivers with no
effect on the amplier’s high-frequency transient response.
Temperature Protection
Technology: C Series ampliers offer cooling facilities that far exceed
the industry norm, including robust cooling fans and a proprietary
Intercooler® copper heat sink with thousands of tiny cooling ns.
Nevertheless, overheating can result from environmental and
operational factors: blocked airow, high ambient temperature, or
prolonged operation at or near current output limits. To guard against
service interruptions or damage, the C Series has implemented
comprehensive over-temperature warning and protection measures.
Thermal measurement points are located on each output channel
and in the power supply. When a pre-set temperature threshold is
reached, a warning status is displayed on the front panel (ashing
LED) and on the DeviceControl GUI via NomadLink. As the critical
temperature threshold approaches, longer warning ashes are given.
When temperature exceeds the critical limit, the output channel
will mute. Temperature is re-measured every six seconds, and the
channel un-mutes when temperature drops to safe levels. Power
supply over-temperature protection operates in a similar way, but
indirectly. There is no separate indicator or action for it, instead it
effects the individual outputs (“hottest rst”).
Benefits: Output transistors and power supply components are
protected from damage due to excessively high temperatures.
High Impedance/Open Load Warning
Technology: C Series ampliers are equipped to sense an open or
extremely high impedance load condition whenever a signal above
approximately -29 dB is present at the input. When this situation
is detected, a warning LED lights on the front panel and indication
is given on the DeviceControl software GUI via the NomadLink
network.
Benefit: Operator is notied of possible fault in wiring or connected
loudspeakers.
Extreme Low Impedance / Short Circuit Protection
Technology: C Series ampliers are designed to accommodate load
impedances as low as 2 ohms. However, any sustained impedances
below this level usually indicates a wiring fault or short circuit.
The C Series amplier detects this condition when current draw is
high (activating the Current Peak Limiter) while simultaneously the
output signal is low. Under these conditions, the output is muted.
The protection circuit sequences at six second intervals; if the fault
condition is no longer detected, the output channel will un-mute.
Benefit: Output transistors are protected from damage, and further
damage to connected loudspeakers is possibly avoided as well.
DC Protection
Technology: All C Series ampliers incorporate circuits that will
immediately sense the presence of DC at the outputs. Since DC is
never present under normal operating conditions, any DC component
indicates an internal fault condition requiring repair. The output is
muted (electronically disconnected) and the corresponding fault
condition is shown on the front panel LED display and on the Device
Control software GUI via NomadLink. Note that only the channel
showing DC fault will mute; other amplier channels will continue
to operate.
Benefit: Connected loudspeakers are protected from potential
damage.
Soft Start
Technology: When rst tuned on, high-power ampliers can draw
a considerable amount of current from the AC mains. If two or
more are turned on simultaneously, this can trip the mains breaker.
C Series ampliers implement a slow, controlled charging of
capacitors to limit current inrush.
Benefits: Several power ampliers may be turned on simultaneously
with greatly diminished chance of tripping the mains breaker.
(Note: The NomadLink network and NLB 60E bridge provide facilities
for sequential turn-on in larger installations.)
TEMP
MUTE
BRIDGE
BRIDGE
FAULT
CH|
A CH|
VHF
CPL
VPL | CLIP
-4dB
-10dB
SIG | HI-IMP
Item no. PF-CS_v3 - 25.04.16