Output Voltage Peak Limiter (Vpl); Output Current Peak Limiter (Cpl) - Zenith 10K4 User Manual

7.4.6 Output Voltage Peak Limiter (VPL)

Voltage Peak Limiter (VPL) is a unique feature in
10K4 amplifiers. It is used to select the maximum
power available on each output channel. VPL levels
are set using the rear-panel DIP-switches; eight level
positions are offered.
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). The VPL allows you to set the correct
maximum output peak power for optimum
performance with the connected speakers. The
correct setting depends on the system type 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.
If you choose a lower VPL setting, you only reduce
the maximum output voltage. At the same time, this
allows more current headroom for low-impedance
loads. The amplifier thus runs at higher efficiency,
with a significantly reduced risk of going into thermal
protection.

7.4.7 Output Current Peak Limiter (CPL)

The Current Peak Limiter (CPL) ensures that the
amplifier will not be damaged by forcing the
amplifier to deliver current levels to the outputs that
exceed the physical limits of the transistors. The CPL
keeps the amplifier within the Safe Operating Area
(SOA.)
The CPL is non-adjustable and has different limit
values depending on model type.
CPL activity is indicated by illumination of an orange
LED for e ach channel on the front panel.
A steadily illuminated orange CPL LED (with MUTE
illuminated) indicates a short circuit situation (or
very low impedance). The output will mute for 6
seconds before measuring the output impedance
again. This will continue until the short circuit is
fixed, at which time the output will automatically un-
mute. An input signal must be present to allow
detection of short circuit or low-impedance
conditions.
The problem can be solved by checking the
input and output cables and examining the
state of the loudspeaker load. If there is no
short circuit present, then the condition may
be rectified by lowering the VPL or input
levels.
Zenith 10K4 Amplifier Manual 20