Усилители мощности стерео — Audia Flight FLS4

The FLS4 is a stereo power amplifier from Audia Flight, the Italian company founded in Civitavecchia in 1996 by Massimiliano Marzi and Andrea Nardini. It belongs to the FLS series, which brings technology from Audia Flight's top Strumento range, particularly the Strumento N°4 power amplifier, into less costly components, and the same power stage is built into the FLS 10 integrated amplifier.

Key specs that matter

The FLS4 delivers 200W per channel into 8 ohms, 380W into 4 ohms and 700W into 2 ohms. Gain is 29dB and input sensitivity 1.41V RMS, with 7.5-kilohm input impedance on both balanced and unbalanced inputs. Frequency response extends from 0.3Hz to 700kHz (-3dB at 1W), slew rate exceeds 160V/us, THD is below 0.05%, signal-to-noise ratio is 110dB and the damping factor exceeds 650 into 8 ohms. Power consumption is 170W idle and 840W with both channels at 200W, and standby draw is below 1W. The chassis measures about 450 x 180 x 440mm and weighs 34 to 36kg.

Engineering and use context

The circuit is fully balanced and uses 32 high-grade output devices. The gain stage is Audia Flight's own design, a Class A current-feedback (transimpedance) circuit that keeps bandwidth wide and slew rate high regardless of gain. This gain stage sits inside an aluminium enclosure filled with epoxy resin, shielding it from interference and keeping all its discrete components at a stable temperature. The output stage is powered by a 2,000VA toroidal transformer wrapped in two ferromagnetic shields and encapsulated in resin, feeding sixteen 18,000uF 50V low-impedance capacitors, 288,000uF in total. In all, the amplifier has 12 power supplies - two high-current supplies per channel plus four stabilised stages per channel for the input and current-feedback circuits - and a separate 15VA transformer powers the logic and protection circuits, isolating them from the audio. Audia Flight omits fuses from the output-stage supply, treating them as a resistance in the power path, and instead protects the amplifier with a current sensor monitored by a microprocessor. Circuit boards use extra-thick copper, and the transformers are mounted on a sub-chassis decoupled from the audio circuit chassis.

Pairing

The FLS4's current delivery into very low loads and its high damping factor suit difficult, low-impedance loudspeakers. Its gain works with any preamplifier, such as Audia Flight's FLS1, and balanced inputs allow long interconnects. Its high full-power draw calls for a dedicated mains socket.

Alternatives

Audia Flight's own Strumento N°4 is the higher-range stereo power amplifier whose technology the FLS series draws on.