12
DC protection
The Attack time for the VHF protection is increasingly shorter at higher frequencies. For
example, an ultrasonic continuous signal will cause the outputs to mute rapidly, where it will
take several milliseconds for a 10 kHz continuous signal to trigger the output mute. This is
shown in the illustration above.
The VHF protection is not a limiter and does not alter the amplifier’s frequency response. it is
implemented solely to detect continuous VHF content. The amplifier will always pass VHF
peaks at full power, with no effect on musical “transients”.
The VHF protection is indicated by a yellow LED on the amplifier front panel, with output
muting for 6 seconds when in action.
NOTE
If you bench test the amplifier using a continuous, full scale sine-wave input
above 10 kHz, the VHF protection will activate and prevent measurement of full
peak output power. (Output will be muted long before maximum output power is
attained.) To measure the true peak output power, use a burst signal.
High-impedance warning(open load)
NOTE
DC protection is implemented on each output to prevent damage to connected
loudspeakers. DC present at the output will trigger muting and illuminate the fault
LED indicator. Any DC present at the output indicates a hardware malfunction
that requires servicing of the amplifier.
A high-impedance (open load) condition is indicated when an input signal above
approximately-29 dB is detected and no functioning loudspeakers are connected to the
amplifier. The fault in indicated by a orange Sig/Hi-imp LED. The indicator is green when a
valid load is present under the same input signal conditions.
NOTE
Since the Hi-impedance detection initially triggers only when the input signal rises
above -29 dB, it might cause the indicator to first turn green, and then red, even
in situations where no speaker is connected.
Low-impedance protection warning
A low impedance or short circuit fault is detected when current draw is high (Current Peak
Limiter active) and when, simultaneously, output signal is low (-4dB LED does not illuminate ).
When this occurs, the amplifier protects the output stage from damage by muting the output
signal and bypassing the circuits. Indication of this fault is a constant orange illumination of the
Current Peak Limiter (CPL) LED on the front panel. The protection will sequence at 6 second
intervals to re-meaure conditions. If the low-impedance fault is no longer detected, the
amplifier will un-mute.
Precautions Introduction Front Panel Rear Panel
Operation and Performance
AMPLIFIER
TD
-
14000
Summary of Contents for TD-14000
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