Operation Manual

5. Operation and performance
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PLM+ SERIES Operation Manual rev 3.0.4
CAFÉ with ESP: CAFÉ (Conguring Ampliers For the Environment) is a dedicated software application for
Windows and OSX that provides tools for system planning, specication and commissioning. CAFÉ incorporates
the Equipment Specication Predictor (ESP), a software module that examines SPL and speaker requirements
for a project and generates requirements for output power on an amplier and system level. ESP will generate a
custom RPM conguration optimizing the power allocation within the frame. 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 sufciently
extreme that any of these circuits become active, indication is provided by amber or red LEDs on the front panel,
and by text notications in the Lake Controller and CAFÉ software. Refer to section 9.1 for more information on
warnings and faults.
5.3.1. Inter–Sample Voltage Peak Limiter (ISVPL)
The ISVPL is a high quality voltage limiter that can deliver seamless signal limiting to any desired level. It ensures
that the voltage at the output terminals never exceeds the dened 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 proles for limiting optimization for a specic frequency band and personal preference. The
proles 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 proles optimized for the different
frequency bands.
5.3.1.1. Low Distortion Profiles
• Universal – The universal prole 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 prole 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 proles do not use the adaptive release time feature. High SPL proles optimized for high frequencies
use less of the look–ahead delay peak–rounding feature; this feature is used most in the Sub prole and least the
HF prole.
• Sub – The Sub prole is optimized for frequencies between 20 – 200 Hz
• LF – The LF prole is optimized for frequencies between 20 – 1200 Hz
• MF – The MF prole is optimized for frequencies between 300 – 6000 Hz
• HF – The HF prole is optimized for frequencies above 1 kHz
Lake-enabled amplifier devices (D Series Lake, PLM+, PLM) that have a smaller peak output voltage capability still
allow ISVPL speaker threshold settings up to 600 V. When a threshold is set above the current maximum capability
of a power output channel, the actual ISVPL will automatically be set to the maximum ISVPL for that channel.
channel and displayed in [ ]. Therefore, the ISPVL threshold can be set at the Module for the speakers’s maximum
capability, and the Module file remains cross-compatible with all Lake-enabled amplifier devices.
5. Operation and performance
PLM+ SERIES Operation Manual rev 3.0.4
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Table 5.3 shows the theoretical maximum output power for a given load impedance and ISVPL setting.
Max. Sinewave Burst Power (Watts)
LLoad Impedance (ohms)
2 2.67 4 8 16
LISVPL SETTING (V peak)
194 4489 5993 4705 2352 1176
193 4489 5993 4656 2328 1164
181 4489 5993 4095 2048 1024
167 4489 5223 3486 1743 872
153 4489 4384 2926 1463 732
121 3660 2742 1830 915 458
101 2550 1910 1275 638 319
83 1722 1290 861 431 215
70 1225 918 613 306 153
56 784 587 392 196 98
47 552 414 276 138 69
38 361 270 181 90 45
17.8 79 59 40 20 10
Table 5.3: ISVPL–to–output examples
The ISVPL threshold may be set at any level between 17.8 V and 600 V in the Lake Controller software. For further
details, please refer to the Lake Controller User Manual.
5.3.2. Current Peak Limiter (CPL)
The output Current Peak Limiter (CPL) ensures that the power output section will not be damaged by forcing it to
deliver current levels at the outputs that exceed the maximum current ratings of the output transistors. The CPL
keeps the output transistors within their Safe Operating Area (SOA). The CPL is non–adjustable.
This condition indicates an attempt to draw excessive current at the output. The output is attenuated until the
output current falls below the maximum current rating. Limiting is performed by the ISVPL limiter in conjunction
CPL activity is shown by red indication on the Power channel LED of the affected output channel and a
corresponding text description on the front panel in Lake Controller and CAFÉ software programs.
Refer to section 9.1 for more information on warnings and faults.
NOTE: If excessive current is indicated, check the output cables and examine the loudspeaker. If
impedance appears normal, you may rectify the condition by altering the ISVPL settings or lowering
input levels. CPL indication can be triggered by excessively low output impedance, possibly the result
of too many loudspeaker cabinets connected in parallel.
5. Operation and performance
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PLM+ SERIES Operation Manual rev 3.0.4