LAB Gruppen FP6400 in excellent condition.
The fP 6400 is a lightweight and space-saving power amplifier, ideal for use in high quality touring sound systems as well as in demanding permanent installations.
Heat and cooling are fundamental problems in extreme high power amplifiers such as the fP 6400. Already in 1990, Lab.gruppen patented a high efficiency amplifier, in fact an evolution of the Class D amplifier. Lab.gruppen therefore call it Class TD. It attains the same high efficiency as Class D, but avoids its drawbacks. Class D has a power-amplifier topology using Pulse Width Modulation (PWM) to achieve high efficiency, but it needs a recovery filter between the output stage and the loudspeaker. Lab.gruppen’s Class TD amplifiers do not need this filter and this is one reason why the Lab.gruppen Class TD obtains the same sonic quality as a traditional Class AB amplifier. Besides the traditionally superb Lab.gruppen sonic performance, fP 6400 offers a full line of important features:
Regulated switch mode power supply
Today there are many lightweight, switch-mode amplifiers in the market. However, the unique Lab.gruppen switch-mode power supply technology offers a number of essential advantages that make it superior to other and seemingly similar power supply designs. The most important features are the regulated power supply and the extreme power efficiency. The regulated power supply easily deals with a very high variation in the AC mains voltage: it can drop by up to 20% below its nominal level – e.g. to 180 V (90 V) instead of 230 V (115 V) – without any problem. Perhaps even greater benefits result from the extreme efficiency of Lab.gruppen amplifiers: only a fraction of the energy from the AC mains is turned into heat. A regulated power supply also presents some other sonic advantages, such as better cone control and the same fast response as a conventional power supply.
Multiple positions Gain switch
To meet the demands for a flexible gain structure in the system, Lab.gruppen offers a multiple position gain DIP switch. The maximum amplifier gain can be set to all industry standards: 20, 23, 26, 29, 32, 35, 38 and 41 dB.
Sophisticated protection circuitry, combining:
– DC protection; protects against infrasonic signals
– VHF protection; protects the loudspeakers against strong very high frequency nonmusical signals above the audible range.
– Thermal protection; prevents overheating. The protection indicators are switched on, as a warning, before the protection process is initiated.
– 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, whilst maintaining full peak power
