Operation Manual
5. Operation and performance
C SERIES Operation Manual rev 2.0.0
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NOTE: The following additional technical information describes GPI port functionality:
Maximum “open” contact voltage: 5 V
Maximum “closed” contact current: 1 mA
Maximum resistance for “closed” contact: 1 kOhm
5.5.4. NomadLink disable switch
The DIP-switch labeled “GPI (- NomadLink)” completely disables the amplier’s connectivity to the NomadLink
network.
5.6. Protection, faults and warnings
5.6.1. Introduction
C Series ampliers incorporate a sophisticated and comprehensive set of protection features. Faults and warnings
are indicated on the front-panel and reported via the NomadLink network for indication on the DeviceControl GUI.
5.6.2. Very High Frequency protection
All C Series ampliers include protection circuits that detect continuous Very High Frequency (VHF) content in the
input signals. The detection begins at approximately 10 kHz and moves upwards to include ultrasonic signals If
VHF signals are detected, the output will mute for six 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, starting at approximately 10 kHz and rising with a -6 dB
slope. This denes the VHF protection area. When continuous output power above the threshold line is detected
the VHF protection becomes active.
The Attack time for the VHF protection is increa-singly 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.
The VHF protection is NOT a limiter and does not alter the amplier’s frequency response. It is implemented solely
to detect continuous VHF content. The amplier will always pass VHF peaks at full power, with no effect on musical
“transients”.