Tesira Operation Manual
11. Operation and performance
28
D SERIES Tesira Operation Manual rev 1.0.0
11.3.8.3. Power Supply / DSP
A power supply (PSU) or DSP temperature warning or fault is indicated by the Alarm LED.
• A warning is indicated by static amber LEDs
• Power supply Temperature Limit (PTL) is indicated by an amber LED
• A fault is indicated with static red LEDs
When the power supply reaches the temperature warning threshold, the Power supply Temperature Limiter (PTL)
is engaged. Total amplier output power is reduced to avoid power supply fault protection (muting of all channels).
Limiting is removed when the temperature falls below the warning threshold.
11.3.9. DC Protection
DC protection is implemented on each power output to prevent damage to connected loudspeakers or any D
Series components. DC present at the output will cause the unit’s power output module breaker to blow. In this
instance the channel’s Amp LED will illuminate red and a service channel fault will be registered in the Tesira and
CAFÉ status views.
NOTE: The power output channel modules are independent of the input voltage. This is not a user
serviceable fault condition and the unit should be returned for repair.
11.3.10. VHF Protection
The D Series includes protection circuits that detect Very High Frequency (VHF) content in the input signal. The
detection is amplitude–, frequency– and time–dependent. It is initiated from 10 kHz upwards and, if continuous
VHF signals are detected above the threshold for more than the attack time, the output will mute for approximately
six seconds before being re-tested. When continuous VHF signal stops, the output unmutes and the amplier
returns to normal operation.
This protection system recognizes only continuous VHF signals at high levels that will not appear in speech or
music. Any such content can therefore be considered as a fault condition. VHF protection is essential to avoid
damage to HF drivers. VHF protection is dependent on a combination of output power level and frequency.
Figure 11.4 shows a decreasing power threshold, from approximately 10 kHz upwards, which illustrates increasing
sensitivity of the protection system with frequency. When continuous output power above the threshold line is
detected, VHF protection becomes active.
Trigger voltage
Voltage [Vrms]
100
90
80
70
60
50
40
30
20
10
0
0 5
10 15 20 25 30
Frequency [kHz]
Fig 11.4: VHF Protection Frequency Sensitivity