Cambridge Audio Azur 340A User Manual - page 12
12 azur integrated amplifier
DC offset protection
The DC offset protection system immediately isolates the amplifier from
the loudspeakers by positively opening an output relay, in the unlikely
event of an amplifier error. Errors of either polarity on both channels are
detected.
Voltage clamping
When rapid transients are applied to reactive loads in extreme
circumstances, flyback pulses can be generated which are larger than
the amplifier supply rail voltages and have the potential to cause harm
to the output devices. The Azur 340A has a comprehensive voltage
clamping system that ensures that such pulses are safely absorbed by
the amplifier and no damage can result.
The Azur 340A protection system comprises of:
Overload and Short-C
Circuit Protection
The Azur 340A is fully protected against excessively low load
impedances, taking into account the fact that a reactive load puts much
more severe demands on a amplifier stage than a pure resistor.
The overload and short-circuit protection systems continuously monitor
the voltage, current and temperature conditions of each of the output
devices, and comparing them with the defined Safe Operating Area or
SOA. This sophisticated system allows the protection to act positively in
case of genuine necessity, but without false triggering.
Over temperature detection
The instantaneous temperatures of the output devices of the Azur 340A
are continuously monitored to ensure that junction temperatures do not
get dangerously high. When an overtemperature condition occurs, the
output is muted until the devices cool. The operation is carefully
controlled to minimise the exposure of the output devices to wide
temperature variations, which can impair reliability by thermal cycling.
This is accomplished by making the muting periods relatively short, so
the amplifier appears to be turning on and off. This puts the least stress
on the output devices.
Careful definition of the protection parameters ensures that the 340A is
not subject to nuisance tripping, but only closes down when the need is
real. Typically this can only happen if the ventilation openings of the
amplifier are obstructed while low-impedance speakers are driven at a
high level for extended periods.
PROTECTION SYSTEM
AP171421 azur 340A English.Chinese User’s Manual Contents - print pantone 2768.qxd 17/01/2005 10:00 Page 11