Lab Gruppen FP6400 – High-Power 2-Channel Touring Amplifier (Class TD Technology)

The Lab Gruppen FP6400 is a legendary high-performance 2-channel power amplifier designed for professional touring and installation sound systems, delivering extreme output, high efficiency, and exceptional audio clarity.

Engineered by Lab Gruppen, the FP6400 became a benchmark in live sound due to its patented Class TD amplifier topology, combining the sound quality of Class AB with the efficiency of Class D.

This amplifier is widely used across Europe in touring rigs, festivals, and high-end installations, where reliability, power density, and sonic performance are critical.

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Power & Output Performance

The FP6400 is built for high-output applications, capable of driving demanding speaker systems with ease.

Output Power (per channel):

• 2 × 1300 W @ 8 Ω
• 2 × 2300 W @ 4 Ω
• Up to 2 × 3200 W @ 2 Ω

Bridged Mode:

• Up to ~5000 W @ 4 Ω

Frequency Response:

• 2 Hz – 42 kHz (wide bandwidth for accurate reproduction)

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Real-World Power Advantage

• Drives large subwoofer systems and mid/high cabinets
• Maintains clarity even at extreme output levels
• High headroom reduces distortion under load

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Amplifier Technology (Class TD)

The FP6400 features Lab Gruppen’s patented Class TD technology, designed to overcome the limitations of traditional amplifier classes.

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Key Benefits of Class TD

• Combines Class AB sound quality with Class D efficiency
• Reduces heat generation while maintaining audio fidelity
• Eliminates typical switching distortion found in standard Class D designs

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Practical Impact

• Cleaner, more transparent sound
• Higher efficiency for touring racks
• Reduced power consumption and cooling requirements

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Physical & Mechanical Details

Form Factor: 2U rackmount (19″ standard)
Dimensions: ~483 × 88 × 347 mm
Weight: ~10 kg

Construction:

• Lightweight yet rugged touring chassis
• Designed for high-density amplifier racks

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Cooling System

• Intercooler™ cooling system with parallel airflow
• Copper heatsinks for efficient heat dissipation
• Front-panel dust filter for long-term reliability

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Connectivity & Signal Flow

Inputs:

• Balanced XLR inputs (with link outputs)

Outputs:

• Neutrik NL4 Speakon connectors

Gain Settings:

• Selectable gain (multiple steps from ~20 dB to 41 dB)

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Practical System Integration

• Flexible input routing for multi-amp setups
• Easy integration into touring racks
• Compatible with external DSP and crossovers

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Protection & Reliability

The FP6400 includes comprehensive protection systems to ensure stable operation:

• Short circuit protection
• Thermal protection
• DC protection
• Clip limiting

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Operational Stability

• Handles large voltage fluctuations (down to ~180 V)
• Maintains consistent performance under heavy load
• Designed for continuous touring use

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System Integration

The FP6400 is commonly used with:

• Funktion-One systems (RES, Evolution series)
• Line array systems requiring high power
• Subwoofer arrays needing strong low-frequency drive

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Typical Configuration

• 1 amplifier powering mid/high sections
• Additional amplifiers for subwoofer systems
• External DSP (e.g., XO4A) handling crossover and tuning

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Result

• High-output, scalable sound system
• Clean signal reproduction
• Reliable performance across different environments

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Acoustic Performance & Real-World Behavior

The FP6400 is known for delivering clean, powerful amplification with strong dynamic response.

Performance Characteristics

• Tight low-frequency control
• Clear midrange and high-frequency reproduction
• High headroom for demanding systems
• Minimal distortion even at high SPL

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Field Insight

In touring environments:

• The amplifier is trusted for “driving heavy systems effortlessly”
• Maintains clarity where lesser amps start to compress
• Widely regarded as a benchmark in analog-style power amplification

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Ideal Applications

Touring and rental sound systems
Festivals and large-scale live events
Club installations and DJ systems
Multi-way loudspeaker systems
Subwoofer-driven high-output systems

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System Advantages in Practice

Power Density:
High output in a compact 2U format.

Efficiency:
Class TD design reduces heat and power consumption.

Reliability:
Proven performance in demanding touring environments.

Flexibility:
Supports a wide range of loudspeaker configurations.

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Summary

The Lab Gruppen FP6400 is a high-power touring amplifier combining advanced Class TD technology, exceptional output capability, and reliable performance, making it a cornerstone in professional audio systems.

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Bottom Line

For professional audio systems in Europe, the FP6400 remains a benchmark amplifier, offering a rare combination of power, efficiency, and sound quality, ideal for touring, installations, and high-performance sound systems.