20
C Series C 20:8X, C 10:8X, C 10:4X and C 5:4X Operation Manual
7.5.3 General Purpose Inputs (GPI)
The GPI functions are enabled only when the front
panel Power and Remote switches are both in the
ON position. GPI functions respond to closure of
the two associated GPI pins. Two modes of remote
power control are provided, depending on the postion
of the DIP-switch “GPI 2 LEVEL TRIG.”
When the GPI 2 LEVEL TRIG dIP-switch is set
to Off:
POWER CONTROL 1
toggles the amplifier’s power
state (ON or OFF) when the connection goes from
Open to Closed and remains closed for a minimum
of approximately 0.2 second. The power state does
NOT change if the connection opens. (This prevents
any unintended change in power state should the
connection be opened by a DC signal circuit fault.)
POWER CONTROL 2
also toggles the amplifier’s
power state (ON or OFF) every time the connection
goes from Open to Closed and remains closed for a
minimum of approximately 0.2 second.
This mode provides redundancy, and also accom-
modates systems with separate closure circuits for
ON and OFF functions.
When GPI 2 LEVEL TRIG dIP-switch is set to
ON:
POWER CONTROL 1
connection is disabled. The
amplifier ignores any change of state on this port.
POWER CONTROL 2
will follow the state of the port.
If the connection is closed, the amplifier turns on; if
the connection is open the amplifier will turn off.
The following is additional technical informa-
tion about the GPI port functionality:
Maximum “open” contact voltage: 5 V
Maximum “closed” contact current:
1 mA
Maximum resistance for “closed” contact:
1 kOhm
7.5.4 NomadLink disable switch
The DIP-switch labeled “GPI (
➟
NomadLink)” com-
pletely disables the amplifier’s connectivity to the
NomadLink network.
7.6 Protection, faults and
warnings
7.6.1 Introduction
The C Series 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.
7.6.2 Very high frequency protection
All C Series amplifiers 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 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, starting at approximately 10 kHz and
rising with a -6 dB slope. This defines the VHF protec-
tion area. When continuous output power above
the threshold line is detected the VHF protection
becomes active.
20 Hz
10 kHz
20 kHz
30 kHz
- 6 dB slope
VHF protection
operation area
Max. Peak
output power
Max. Continous
output power
Output
power
Attack time
VHF protection
Slow
Fast
20 Hz
10 kHz
20 kHz
30 kHz
Figure 10: VHF protection operational area
7 OPERATION AND PERFORMANCE