Signal Flow And Processing 8; Signal Flow - Lab.gruppen PLM Series Operation Manual

8.1 signal Flow

The design of the input stage of the PLM has sufficient
headroom to make it almost impossible for signal
clipping to occur. Because of the integration of the
Dolby Lake processing system in the PLM, there are
four separate points in the signal chain where signal
level can be adjusted. It is important to understand
the significance of the various level adjustments to
obtain optimum performance from the PLM.
Adjustment of input levels to, and output levels from,
the Dolby Lake processing system (the MODULE
inputs and outputs) plus the PLM's power stage gain
can be made either from the front panel display screen
or the DLC PLM Edition software. The per-channel
attenuation can only be made from the front panel
by selecting MENU > MODULE > ATTENUATION.
In addition to these level adjustments, the physical
inputs to the PLM can be mixed with level adjustment
pre the Dolby Lake module; this adjustment is only
available from the DLC PLM Edition software.
Unlike traditional amplifiers, the PLM can be muted
at several different points in its audio chain. It is
important to understand where these mutes are
located and how to control them.
It can be seen from figure 8-1 that muting is possible
at four points within the signal chain:
Figure 8-1: PLM Signal Flow Diagram (Part 2)
Module Output Gain
Levels
LimiterMax
Phase Rev
RMS / Peak
Mute
Levels
LimiterMax
Phase Rev
RMS / Peak
Mute
Levels
LimiterMax
Phase Rev
RMS / Peak
Mute
Levels
LimiterMax
Phase Rev
RMS / Peak
Mute
Module Output Mute

sIGNAL FLOW AND PROCEssING 8

1. PLM Input Mutes – These mute the actual PLM
input signal, whichever input type is selected (analog,
digital, etc.)
2. Module Input Mutes – These mute the inputs
to whichever Dolby processing Modules have been
defined for the PLM configuration, and will be post
any input mixing and routing.
3. Module Output Mutes – These mute the individual
processing module outputs, e.g. Hi, Mid, Low
channels.
4. Power Output Mutes – These mute the signals
within the actual amplifier output power stages
themselves.
The Current Peak Limiter (CPL) dynamically limits the
drive to the power stage based on three parameters:
sensed output current level, feedback from the output
stage, and sensed voltage clip from the ISVPL. This
ensures that power output is maintained within the
design limits of the PLM.
The adjustable Inter-Sample Voltage Peak Limiter
(ISVPL) sets the PLM's maximum output voltage
and therefore also the maximum output power. The
ISVPL setting is made via MENU > MODULE >
LIMITERS > ISVPL, and can also be set from the
DLC PLM Edition software.
Attenuator
Attenuator
Mute ISVPL
Phase Rev
Attenuator
Mute ISVPL
Phase Rev
Attenuator
Mute ISVPL
Phase Rev
Attenuator
Mute ISVPL
Phase Rev
Amplifier Output Mute
Amplifier Gain
LoadSmart
Amp Gain
SpeakerSafe
LoadSmart
Amp Gain
SpeakerSafe
LoadSmart
Amp Gain
SpeakerSafe
LoadSmart
Amp Gain
SpeakerSafe
PLM Series Operation Manual 23
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