Overall efficiency and heat dissipation always have been fundamental problems in extremely high power amplifiers such as the fP 6400. As early as 1990, Lab.gruppen had achieved a breakthrough with a patented a high efficiency amplifier that represented a major evolution beyond typical Class D approaches. Designated Class TD®, this technology obtains the same high efficiency as Class D, but avoids the inherent drawbacks. For example, a typical Class D topology employs Pulse Width Modulation (PWM) to achieve high efficiency, but this requires a steep recovery filter between the output stage and the loudspeaker. In contrast, Lab.gruppen’s Class TD design keeps the audio signal within the analog domain, eliminating the need for filtering and therefore offering the same sonic quality as a traditional Class AB amplifier.

In addition to traditionally superb Lab.gruppen sonic performance, fP 6400 offers a full line of important features: Regulated Switch Mode Power Supply (R.SMPS™).

Switch-mode amplifiers are commonplace in today’s amplifier market. However, Lab.gruppen’s unique Regulated Switch-mode Power Supply (R.SMPS) technology offers a number of essential advantages that make it superior to other, seemingly similar power supply designs. The most important features are the precise regulation and the extreme power efficiency. The regulated power supply easily deals with high variations in the AC mains voltage: it can drop by up to 20% below its nominal level (e.g. to 180 V instead of 230 V) without affecting audio performance. The power supply is also exceptionally efficient, with only a fraction of the energy from the AC mains is turned into heat. A regulated power supply also affords other sonic advantages, including better cone control while retaining the same fast response as a conventional power supply.

• Multiple Position Gain Switch (M.PGS)
• Intercooler® cooling system with front-to-rear airflow and easily accessible dust filters
• Improved low-end power bandwidth
• Link (loop-thru) output with XLR-type connector
• Extruded front panel for increased stability
• Bridged mono outputs in one Speakon® connector
  
  

Multiple Position Gain Switch (M.PGS)

• Multiple position gain switch
• Can be set to all industry standards: 20, 23, 26, 29, 32, 35, 38 and 41 dB
  
  

Sophisticated protection circuitry, combining:

• DC protection – Blocks infrasonic signals due to fault conditions
• VHF protection – Protects the loudspeakers from sustained (non-musical) very high frequency signals above the audible range
• Thermal protection – Protects the amplifier from overheating
• AC protection – Shuts down the power supply if the line voltage is outside the operating voltage
• Clip limiter – Prevents severely clipped waveforms from reaching the loudspeakers while maintaining full peak power