Amplifier And Load Protection Systems - Lab.gruppen PLM 20K44 Operation Manual

5. Operation and performance
CAFÉ with ESP: CAFÉ (Configuring Amplifiers For the Environment) is a dedicated software application for
Windows and OSX that provides tools for system planning, specification and commissioning. CAFÉ incorporates
the Equipment Specification Predictor, a software module that examines SPL and speaker requirements for a
project and generates requirements for output power on an amplifier and system level. For more information on
CAFÉ and ESP, please consult the documentation supplied with the CAFÉ software download.

5.3. Amplifier and Load Protection Systems

The PLM+ is equipped with a comprehensive set of protection circuits. If operating conditions become sufficiently
extreme that any of these circuits become active, indication is provided by LEDs in one or more soft function
buttons 5-8, together with adjacent warning text. In addition to this, notification is also presented within the Lake
Controller software and within system log files.
5.3.1. Inter-Sample Voltage Peak Limiter (ISVPL)
The ISVPL is a high quality voltage limiter that can deliver seamless limitation to any desired level. Its ensures that
the voltage at the output terminals never exceeds the defined threshold.
It operates on these principles:
• The signal is delayed slightly to allow the ISVPL to look-ahead and reduce the gain before voltage in excess
of the threshold can appear at the output. This results in zero voltage overshoot at the output with a rounded
limitation up to the threshold.
• The amplitude of the output signal between digital samples is predicted which permits the ISVPL to respond to
analog peaks that may occur at the digital to analog converter.
• The release time of gain reduction is adaptive depending on the dynamics of the signal.
It is possible to select different ISVPL profiles for limiting optimization for a specific frequency band and personal
preference. The profiles are divided into two categories, with one category optimized for low distortion and the
other focusing on producing high sound pressure level (SPL). Within each category there are profiles optimized for
the different frequency bands.
5.3.1.1. Low Distortion Profiles
• Universal – The universal profile is a soft limiter that can be used for all frequencies and is conservative in its
action upon VCL and CPL.
• Sub/LF – The Sub/LF profile is tuned for frequency bands below 600 Hz. It has longer attack and release times
and is less conservative when it comes to acting upon VCL and CPL.
•
5.3.1.2. High SPL Profiles
High SPL profiles do not use the adaptive release time feature. High SPL profiles optimized for high frequencies
use less of the look-ahead delay peak-rounding feature; this feature is used most in the Sub profile and least the
HF profile.
• Sub - The Sub profile is optimized for frequencies between 20 - 200 Hz
• LF - The LF profile is optimized for frequencies between 20 - 1200 Hz
• MF - The MF profile is optimized for frequencies between 300 - 6000 Hz
• HF - The HF profile is optimized for frequencies above 1 kHz
18
PLM+ SERIES Operation Manual rev 1.0.0