Inter-Sample Voltage Peak Limiter (Isvpl); Maxpeak Level (Maxpeaklvl); Maxrms Level (Maxrmslvl); Maxrms Corner (Maxrmscor) - Lab.gruppen PLM Series Operation Manual

9 FRONT PANEL INTERFACE
9.12.2.5.1 Inter-sample Voltage Peak Limiter
(IsVPL)
The purpose of the ISVPL is to prevent the voltage
at the PLM's output terminals exceeding a pre-
determined value. Selecting ISVPL (soft button 2)
permits adjustment of this value, in the range 17.8
V to 153 V (model dependent). (Note this represents
an instantaneous peak voltage, not the RMS value
of the output signal.)
The remainder of the limiter adjustments
refer to the LimiterMax within the Dolby
Lake processing system, which features
control of both peak and RMS levels, referred
to as MaxPeak and MaxRMS respectvely. Full details
of the operation of LimiterMax can be found in the
DLC User Manual, chapter 5.2.3 to 5.2.5.

9.12.2.5.2 MaxPeak Level (MaxPeakLvl)

This sets the maximum peak signal level at the
processor's Module outputs It is adjustable from -30
dBu to +30 dBu in 0.1 dB increments. The MaxPeak
level parameters may also be adjusted from the DLC
PLM Edition software.
The Group Sum value is also displayed (in brackets)
for this parameter for each channel.

9.12.2.5.3 MaxRMs Level (MaxRMsLvl)

This sets the maximum RMS signal level at the
processor's Module outputs. It is adjustable from -30
dBu to +30 dBu in 0.1 dB increments. The MaxRMS
level parameters may also be adjusted from the DLC
PLM Edition software.
The Group Sum value is also displayed (in brackets)
for this parameter for each channel.

9.12.2.5.4 MaxRMs Corner (MaxRMsCor)

The transfer curve of the RMS section of the Dolby
Lake LimiterMax is selectable to "soft-knee" or
"hard-knee" characteristic. With a "soft-knee" curve,
limiting is gently increased as signal level approaches
the threshold, whereas with a "hard-knee" curve,
full limiting is applied to any signal exceeding the
threshold by any amount, but none to signals below
the threshold. The Corner parameter is selectable in
0.1 dB increments from -100 dB to 0 dB, this figure
representing the level below the limiter threshold at
40 PLM Series Operation Manual
which compression commences. Thus, the greater
the value (negatively), the "softer" the knee. A setting
of 0 dB implies a "hard-knee" characteristic. The
LimiterMax Corner parameter may also be adjusted
from the DLC PLM Edition software.

9.12.5.5.5 MaxRMs Attack (MaxRMsAtk)

This sets the attack time of the MaxRMS limiter. It
is selectable in 0.1 ms increments from 1mS to 500
ms. The attack time parameters may also be adjusted
from the DLC PLM Edition software.

9.12.2.5.6 MaxRMs Release (MaxRMsRel)

This sets the release time of the MaxRMS limiter.
It is selectable in 0.1 ms increments from 1mS to
500 ms. The release time parameters may also be
adjusted from the DLC PLM Edition software.
It can be seen that the MaxRMS attack and
release times may be set to different values.
Note that on the DLC PLM Edition software,
there is an additional auto-time constant
function, which sets them to crossover-dependent
optimal values for best RMS operation.
Adjustment of attack and release times can
only be made to one channel at a time;
pressing soft buttons 5–8 selects each
channel in turn.

9.12.2.6 Mutes

This option is selected by pressing soft button 8
(Mute) from Menu è Module.
The audio signal may be muted at the Module input
stage or the Module output stage from within the
menu system. (Note that the Module input mute
can also be actioned from the front panel when in
METER mode.)
The display shows the current mute status for the
two mute positions as Muted or Not Muted. Soft
buttons 2 and 3 select the Input Mutes for Modules
A and B respectively, and buttons 5 – 8 the Module
output mutes for the four output channels. Once
selected, the mute state can be changed with the
rotary encoder.
Note that the LEDs in the associated soft buttons