Lab.gruppen C Series 5:4X - Manual (Page 25)

C Series C 20:8X, C 10:8X, C 10:4X and C 5:4X Operation Manual rev. 1.1.4
Operation and Performance
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5.4.5 Amplifier sensitivity
Sensitivity is defined as how many volts (rms) or dBu (referred to 0.775 Vrms) are required to achieve full
(maximum) output power. As the output power varies with the load impedance, 4 ohms is usually the common
reference.
Since C Series amplifiers are capable of providing multiple maximum output power levels through use of the
VPL feature, many sensitivity calculations may be required for a single amplifier. We recommend use of the
DeviceControl software to simplify this process. DeviceControl’s Device View page, used in combination with
the DIP-switch settings display, will automatically produce a sensitivity calculation from the given data (VPL,
Gain and load).
5.4.6 Output Voltage Peak Limiter (VPL)
The Voltage Peak Limiter (VPL) is a unique feature in C Series amplifiers. It is used to select the maximum
power available on each output channel. Four levels can be set using the DIP-switches on the amplifier’s rear
panel.
V peak Vrms
100 70.7
63 44.5
45 31.8
32 22.6
Figure 6.4.6: VPL
values in both V peak and
Vrms
The values for VPL are displayed as maximum Voltage Peak. To translate Voltage Peak into Vrms, you must
divide the Voltage Peak values by 1.41 (see table 7.4.6).
The VPL allows you to set the correct maximum output peak power for optimum performance with the con-
nected speakers. The correct setting depends on the system type (low or high impedance) and the specific
load connected to the channel. Since each channel can be configured to deliver either very high voltage peak
power OR high current draw at low impedances, it is important to set the VPL correctly.
To configure an individual output channel for a constant voltage system, you simply adjust the DIP-switches
to the desired voltage. However, when using an output for a low-impedance system ( 4, 8 or 16 ohms), then
you may need to adjust the VPL to a lower setting to avoid either delivering excessively high continuous power
to the speaker or overheating of the output channel through high current draw. For example, with a very “hot”
continuous output signal, the temperature could rise to a critical level and activate Temp warning or even Temp
Mute. Lowering the VPL setting usually will solve this situation.
If the Current Peak Limiter is active or indicates low impedance, lowering the VPL setting can rectify this
situation as well.