Lab.gruppen C Series 88:4 - Manual (Page 24)

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5. Operation and Performance
C Series C 88:4, C 68:4, C 48:4, C 28:4 and C 16:4 Operation Manual rev 2.2.3
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).
5.4.5 Output Voltage Peak Limiter (VPL)
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. Eight levels can be set using the DIP-switches on the amplifier’s rear-panel.
V peak Vrms
141 100
118 84
100 70
85 60
71 50
59 42
50 35
42 30
The values for VPL are displayed as maximum voltage peak (V peak). To translate V peak into Vrms, you must
divide the Voltage Peak values by 1.41 (see table).
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 (2, 4, 8 or 16 ohms), then
sometimes you 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 normally 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.
5.4.6 Constant voltage 70 V and 100 V systems setup and operation
When using C Series amplifiers to drive constant voltage (high-impedance) speaker systems at 70 Vrms or 100
Vrms, you can in most cases simply connect the speakers to the amplifier output terminals, select the correct
VPL setting, and place the amplifier in service.