44M Series Amplifiers


Offering a unique combination of power and audio performance, seamlessly combined with advanced DSP and network control, the 44M Series range of four channel amplifiers is available in models developing between 1,500 Watts and 5,000 Watts per channel.

Over designed high capacity power supplies ensure the full power specification can be delivered into 2 ohms with all channels driven while remaining highly efficient.

  • 44M Series Features
  • Four channels of sonically pure Class D amplification
  • Unique, precise, 96kHz Digital Signal Processing
  • Over‐designed switch mode power supply
  • 85V to 240V Auto-sensing PSU
  • 6,000 to 20,000 watts RMS total output
  • Full front panel user interface
  • Ethernet network for system operation and monitoring
  • Analogue, AES3 and optional Dante™ / AES67 digital network audio
  • Powerful grouping & multi‐layer EQ
  • Accepts 48kHz and 96kHz FIR files via System Engineer (certain models)
  • Fully designed and engineered in house by Linea Research
  • Manufactured in the UK

Linea’s 44M Series of four channel amplifiers are optimised for live sound applications. Offering a unique combination of massive power and peerless audio performance integrated with unique DSP, the 44M Series represents an unmatched advancement in amplifier technology.

Sharing the same feature set and form factor as Linea's 48M Series of eight channel amplifiers the 44M Series is available in models that develop between 1,500Watts and 5,000 Watts per channel (up to 10,000 Watts for a bridged pair). Unusually these are not, ‘transient’, ‘burst’ or ‘peak’ power figures, they are the power levels that are delivered by all channels simultaneously even when driven with the same dense program material.

With Linea amplifiers there is no need to ration power between channels, you can use all the power you have paid for all the time. This has been independently verified.

Linea can do this because state of the art components and a finely optimised design results in an amplifier that is between 7% and 10% more efficient than any competitive product. This efficiency gain directly translates in to the generation of about half the wasted energy (heat) which is clearly significant. In addition to reducing energy costs high efficiency results in generous power reserves ensuring that pristine sound quality is maintained even under the most extreme conditions.

Uniquely, each channel can be configured to deliver its maximum power into 2, 4 or 8 Ohms (2 or 4 Ohms for the M20 model), nominal loads as well as 25V, 70V & 100V constant Voltage (CV) lines. This offers designers and integrators unparalleled flexibility and cost effectiveness.

Ethernet is used for remote control and monitoring while a front panel, optimised for use in challenging live environments, allows full local control of all features. Control via Linea’s intuitive SE System Engineer PC application provides many convenient and time saving features such as very flexible management of presets, and Overlay grouping of Mutes, Gains, Delays and EQ across an entire system.

The advanced 96kHz DSP is fully integrated into the product and provides an array of unique and genuinely useful features. Because all aspects of the DSP algorithms are designed and hand crafted in house by Linea, they are not available on products from any other manufacturer. For example, LIR linear phase crossover filters which are as easy to use as more conventional filter shapes, and have less latency than FIR filters. Also the powerful VX Limiter suite which sports Peak, RMS and Excursion limiting, as well as multi-band limiting for passive 2-way enclosures.

RMS per channel, all 4 channels driven
Model          2 Ohms             4 Ohms              8 Ohms               70/100V
44M20          5000W              3000W                1500W              3500/5000W
44M10          2500W              2500W                1500W              2500/2500W
44M06          1500W              1500W                1500W              1500/1500W

General Specifications­

Number of channels Four
Total power output, all channels driven 20,000, 10,000 and 6,000 Watts RMS
Audio inputs 4x Analogue, 2x AES3 and 4x Dante™ / AES67 (factory fitted option)
Digital Signal Processing High performance DSP processing on all inputs and outputs
Control, monitoring and system status alarms Ethernet network


Volt-free relay and contact closure port

Power-save modes Standby after user defined time, instant wake up on audio


Deep ECO sleep after user defined time, wake up on command

System sleep and wakeup Front panel switch, network command and audio detection

Power Output

Model 44 Series M20 44 Series M10 44 Series M06
Power specification RMS output power per channel, all channels driven with continuous program material and a nominal ambient temperature of 40°C / 105°F
Crest Factor of 4 (12dB), 2-Ohm nominal load 5,000W 2,500W 1,500W
Crest Factor of 2.8 (9dB), 4-Ohm nominal load 3,000W 2,500W 1,500W
Crest Factor of 2 (6dB), 8-Ohm nominal load 1,500W 1,500W 1,500W
Bridged, per channel pair, 4-Ohm nominal load 10,000W 5,000W 3,000W
100V line (CV) operation, Crest Factor 4 (12dB) 5,000W 3,000W 1,500W
70V line operation, Crest Factor 4 (12dB) 3,500W 2,500W 1,500W
25V line operation, Crest Factor 4 (12dB) 1,250W 885W 685W

Audio Performance

Amplifier topology Linea Research high performance Class D
Amplifier modulation scheme Low feedback, multiple loop, with feed-forward error correction
Dynamic range to amplifier output Analogue input, better than 113dBA typical


AES / Dante™ input, better than 114dBA typical

Gain (with all DSP level controls set to 0dB) 32dB
Frequency response, 4 Ohm load <7Hz to >30kHz, 4 Ohms, -2.5dB points
Total harmonic distortion, THD <0.05% typical, 1kHz signal, AES17 filter, 4 Ohm load
Inter-channel crosstalk, worst case combination better than -85dBr at 1kHz and -75dBr at 10kHz
Maximum analogue input level +20dBu
Analogue input sensitivity range for full output 0dBu to +20dBu, continuously adjustable
Analogue input (four channels) Input 20k Ohm, electronically balanced, link directly connected to input
Analogue ground scheme AES48 standard compliant
AES3 input (two audio channels) Transformer isolated with unique active cable equalisation for extended range
AES3 link (two audio channels) Active AES3 signal regeneration. Automatic direct bypass to the AES3 input ensuring the audio signal will still flow even when the amplifier is powered down
AES3 supported sampling rates 24kHz to 192kHz (auto locking)

Digital Signal Processing

Resolution 40 bit, Linea Research proprietary algorithms
Sample rate 96kHz throughout
Physical inputs to DSP drive modules 4x analogue, 2x AES & 4x Dante™ / AES67 inputs can be routed to four DSP drive modules
Drive module input processing Input signal routing, delay, gain, HPF, Phase, Mute


EQ: 2x low shelf, 6x PEQ / band pass and FIR shelving filters

Drive module output processing Source, delay, gain, Phase, Mute, crossover filters, VX limiters


EQ: low shelf, 8x PEQ / band pass and shelving filters

Preset management 10 snapshots for device wide setup, 50 presets for loudspeaker settings


Presets can be recalled to sets of outputs or individual outputs as required

Unique high performance processing  
Overlays Twelve additional independent overlays of EQ, Delay and Gain


Flexible grouping for effective control of many amplifier channels in large systems

Class leading VX limiters See the ‘speaker protection systems’ section
Hardman crossover filters Better out of band rejection than Linkwitz-Riley
LIR crossover filters Linear Phase without the compromises of FIR filters

Power Supply

Topology (main power supply) Linea Research high performance Series Resonant
Topology (auxiliary and standby supplies) Low quiescent Eco-Flyback
Internally stored energy >600 Joules
Nominal mains input voltage range 85V to 240V Power supply automatically detects voltage and configures accordingly
Mains input frequency range 47Hz to 63Hz
Mains inrush current (max for <10ms) 6A at 115V and 12A at 230V

Protections Systems

Under all circumstances the control and protection systems will endeavour to deliver the maximum power possible for a given set of conditions, applying limiters only in extreme circumstances. Muting will only occur when a dangerous situation is detected, normal operation automatically resuming when the condition clears.
System protection Speaker protection
Excessive power supply current or amplifier output current Sustained clipping prevention
Excessive temperature per sub system: PSU, amplifier and DSP DC offset protection
Mains voltage within acceptable limits Excessive HF energy (VHF) limiter
Internal power rails producing correct output  
Fans operating at correct speed VX audio output limiters
  Vx provides a linear phase virtual crossover and two limiter paths on each output. This unique system delivers effective protection for systems that incorporate passive crossovers.
Power distribution protection systems Vx Limit      Multi-band peak limiter, two per output
Mains inrush current limiting for soft start and anti-surge Vx Max       Multi-band overshoot limiter, two per output
Mains average current limiting for mains breaker management X-Max         Driver excursion limiter
Randomised initialisation when remotely powered up T-Max         Driver thermal limiter (long term power limiter)
Monitoring, measurements recorded against time Monitoring, device statistics and counters
Supply current Number of power cycles counted
Supply voltage Number of mains brownout events counted
Thermal Capacity Fan speeds continuously monitored
Each driver current Fan under-speed events counted
Each driver impedance Various protection mute events counted
Protection limiting for each output Driver Impedance continuously monitored
An inbuilt notification system is provided to indicate problems to remote devices either via the network or the Volt-free changeover relay contacts accessible on the rear panel.


Cooling Dual vari-speed fans, front to back airflow. Washable, tool less change filter media.
Analogue IN and LINK 4x female and 4x male Neutrik™ XLR
AES3 dual channel IN and LINK 1x female and 1x male Neutrik™ XLR
Amplifiers output 4x Neutrik Speakon™ NL4 connectors
Mains input connector Neutrik 32A Powercon™
Dante Primary and Secondary 2x Shielded RJ45
Relay output & contact closure inputs Phoenix™ pluggable terminal block (supplied)
Front panel display (backlit) Graphical, high contrast, daylight visible
Front panel encoders Two, indented, velocity sensitive
Front panel push buttons Large, tactile, illuminated
LED indicators Bright, easily differentiated
Enclosure Standard 19” 2U (88mm), 357mm (14”) deep  with handles and optional rear support
Net Weight 12.5kg (27.5 pounds).


Total Integration


Sys Tunes


System Engineer Application

Thanks to the power of Obcom, System Engineer becomes much more than just a remote control panel for an 44M Series. System Engineer and any connected device(s) become intimately intertwined, faithfully duplicating any control adjustments whether they are made in System Engineer or on the front panel of the device itself. Adjust a gain control on the device and watch the gain value in System Engineer smoothly slide in sympathy. They simply cannot get out of ‘sync’. You can also update the firmware in the unit via System Engineer — even via the network.
Each input and each output can be named in System Engineer. These names not only appear for the User on the System Engineer control panels, but also show when scrolling through the inputs and outputs on the device itself. Should you wish to change the factory presets in the field, modified Factory files can be distributed and loaded by the user without disturbing the user presets, and without the user being able to access the factory settings in the factory presets.

The full 44M Series control panels in System Engineer: