11
Precautions Introduction Front Panel Rear Panel Operation and Performance
Figure 10
VHF protection attack time vs output power/frequency
Safe Operating Area Detector(SOAD)
VeryHigh requency (VHF) protection
The Safe Operating Area Detector(SOAD) compares output voltage against output current
to enure that the output transistors are working inside their safe operating area.
The SOAD provides fault monitoring and input to the Current Peak Limiter 9CPL0. The
SOAD has no dedicated indicator, and it operation is revealed only in conjunction with
features such as the CPL.
The Td14000 amplifier include protection circuits that detect continuous Ver High
Frequency content in the input signal. The detection begins at approximately 10kHz and
moves upwards to include ultrasonic signal. If VHF signals are detected, the output will
mute for 6 seconds before re-measuring. Once no continuing VHF signal is detected, the
output un-mutes and returns to normal operation.
This feature recognizes that continuous full-scale VHF signals do not appear in “natural”
sources such as music. Any such signals can therefore be considered as a fault when
present. VHF protection is essential in avoiding damage to high frequency drivers.
The VHF protection operational area is dependent on output power level and frequency.
The illustration below shows a decreasing threshold on the output power level, staring at
approximately 10 kHz and rising with a -6 dB slope. This defines the VHF protection area.
When continuous output power above the threshold line is detected the VHF protection
becomes active.
Output
power
-6 dB slope
Max. Peak
output power
Max. Continous
output power
20Hz 10kHz 20kHz 30kHz
slow
fast
20Hz 10kHz 20kHz 30kHz
Attack time
VHF protection
VHF protection
operation area
AMPLIFIER
TD-14000
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General