Four channel power amplifier

The PLM20K4 is a high performance, easy to use signal processor providing processing for up to 4 inputs and 8 outputs, taking advantage of the latest advances in analogue to digital conversion and digital signal processing technologies. In addition to the standard presets for all Acoustics loudspeakers, a number of user-customisable blank slots are also available.


The PLM20K4 features a minimal signal path design, and a 96kHz sampling frequency provides for a nominally flat response beyond 40kHz. This, together with a powerful 4th generation digital signal processor, adds up to deliver the ultimate in sonic transparency and a stunning open, natural sound quality.


The PLM20K4 incorporates a comprehensive and innovative limiter suite that provides optimum control for all Acoustics loudspeaker models. It includes a Virtual Xover limiter providing dynamic control for passive two-way enclosures, an Xmax excursion limiter with sliding high pass filter which retains dynamic impact whilst effectively protecting drivers, Tmax transducer thermal modelling which addresses long term overload, and an overshoot limiter which governs the amplitude of transient signals, retaining average power whilst constraining peaks.


As well as the standard Butterworth, Bessel, Linkwitz-Riley and Hardman filters, the The PLM20K4 offers a unique “Linea Impulse Response” (LIR) crossover filter which gives a Linear Phase crossover that has a constant delay regardless of frequency (unlike other types of crossover which delay different frequencies to a different extent, thus smearing the arrival time). The LIR crossover can thus be described as having a flat Group Delay response, and thus entirely free of Group Delay Distortion, this is exactly the same as can be provided by common FIR filtering but without the complications and disadvantages inherent with the FIR technique. The shape of the LIR crossover filter is similar to a 4th order Linkwitz-Riley filter, and maintains zero phase difference between the adjacent bands across the crossover region to keep the polar response rock steady.


The PLM20K4 is built around a 1U all-metal chassis, which provides a roadworthy package whilst keeping the weight low. The front panel provides an intuitive set of controls and indicators to enable simple and straightforward operation. LED clusters indicate presence of signal, and level from -12dB to +12dB as well as clip, for each of the four inputs. Further LEDs show if AES3 connections are activated for channel pairs. Six illuminated push buttons and three rotary encoders provide the user interface for all the input and output functions, as well as the utility features, in conjunction with the clear backlit graphical display.


The rear panel houses the Neutrik® XLR input and output connectors, and IEC mains power receptacle. A Dante digital audio network card can be optionally fitted .

▼System type

Power amplifier type: 4-channel Class D digital power amplifier with DSP

Number of channels: 4 channels, each two can be bridge

Output power: 1500W/ CH@ 8 ω, 3000W/ CH@ 4 ω, 5000W/ CH@ 2 ω;

10000W @ 4 ω (bridge)(measured using 1kHz continuous sine wave)

Constant voltage line output: 1250W, 25V line; 3500W, 70V line, 5000W, 100V line

Input impedance: 20KΩ (balanced), 10KΩ (non-balanced)

Maximum input level: +20 dBu

Dynamic range: > 113dBA, analog input, > 114dBA AES/Dante input

Frequency response: 7HZ-30khz (-2.5dB points, 4 ω Load)

Total harmonic distortion: <0.05% typical @ 1kHz, 4 ω Load

Conversion rate: >60V per microsecond

>800 AT amplifier output, ref 8Ω

Control mode: Ethernet (RJ45), connected to a PC for setting and real-time monitoring

PC software: LA Audio PodWare

▼Input and output interfaces


4 x Neutrik XLR female (audio input),

4 x Neutrik XLR male (loop pass output),

 1x Neutrik XLR female (AES3 input),

 1x Neutrik XLR male (AES3 output),

 2 x RJ-45(Dante input/output),

1 x RJ-45(TCP/IP network port),

1 xRestart switch (button),

1 x 6 way Mini Phoenix connector (GPI port),

 4 x NeutrikSpeakon Output connector (4 cores),

1 x Neutrik 32A Powercon power port 

·Front panel control and indication:

1 x LCD graphic LCD display,

1 x power switch,

1 x switch / standby LED(green/red),

4 x function mode indicator,

 2 x bridge mode indicator,

4 x input level indicator,

 4 x output level indicator,

6 x multi-function button,

2 xProgrammable knob can be pressed,

4 x output mute shortcut button


DSP: all input/output channels are equipped with high-performance 96kHz/48kHz DSPS

DSP sampling rate: 96kHz (48kHz for FIR filter implementation)

DSP module input: input routing, delay, gain, high-pass filter, polarity, mute;EQ: 2 x low frequency shelf filter, 8 x PEQ/band pass and shelf filter

DSP module output: signal source selection, delay, gain, polarity, mute, frequency divider filter, VX limiter;EQ: 2 x low frequency shelf filter, 8 x PEQ/band pass and shelf filter


Cooling: static noise continuous variable speed fan, exhaust from back to front

Operating temperature: -10℃~50℃

Dimensions: 483 x 88 x357 mm (19 x 3.5 x 14.1 inches)

Weight: 12.5 kg(27.5lbs)

Related products