Усилители мощности моно — Fjord Audio P150

The P150 is a valve monoblock power amplifier from Fjord Audio of South Korea, designed around a fully balanced signal path, pure class A operation and zero negative feedback. It is the only power amplifier shown in the Fjord Audio catalogue, which also lists preamplifier, phono and accessory categories, and a matched pair is priced at about USD 27,500.

Key specs that matter

Each chassis produces 90 W into 4 ohm, a figure the maker quotes as peak output. Frequency response runs from 10 Hz to 20 kHz at the 3 dB points, signal-to-noise ratio is 91 dB and total harmonic distortion is 0.1 percent. Signal enters through one XLR connector with a sensitivity of 920 mV. Every unit measures 336 x 542 x 457 mm (width x height x depth), weighs 35 kg and draws around 980 W from the mains.

Engineering and use context

Every chassis carries two 12AU7 tubes for the input and driver stages plus four KT150 output tubes. Fjord Audio calls its circuit DFD, short for Direct Full Difference, a proprietary topology that keeps the path fully balanced from input to output. Rather than using feedback to lower noise and distortion, as most valve amplifiers do, the designers left it out altogether. The output transformer is a custom unit wound on an EI core. Power comes from a shielded 2 kW toroidal transformer, and the company states that the supply accounts for roughly 75 percent of the whole design and cost. Automatic bias control monitors the operating conditions continuously, and protection and standby circuits are built in. Inside the tower-shaped chassis, whose look takes its cue from Norwegian fjords, the parts sit on three levels - the transformer at the bottom, the power supply above it and the amplification circuitry at the top - to keep electromagnetic interference away from the signal stages. Thick aluminium columns and panels form the structure, combined with wood accents. The circuit is built on a printed circuit board made to military specifications. Buyers can choose among high-gloss oak, matte oak and light wood finishes for the chassis.

Pairing

As a monoblock, the P150 is used in pairs, one chassis per loudspeaker, and the preamplifier driving them needs balanced XLR outputs because no single-ended input is fitted. The 920 mV sensitivity sets the preamplifier output level required to reach full power, and a pair draws close to 2 kW from the mains in total.

Alternatives

Fjord Audio shows no other power amplifier besides the P150, and the maker offers no second amplifier of this type.