Усилители мощности моно — Fluo M500

The M500 is the true monoblock in the FLUO range, the only model where each channel gets a chassis of its own, and left and right speakers therefore call for a pair. FLUO is based in Winchester, England, and its amplifiers revive an idea from Danish engineer Ole Lund Christensen. He began building power amplifiers in 1982 around an industrial N-channel MOSFET of only 70 W, which led to the SLT 250, rated at 2 x 250 W into 8 ohms or 1,000 W bridged. In 1995 he completed the SiriuS DM 200, which the company calls the first power amplifier to use a single MOSFET per channel, producing 200 W into 8 ohms, and five years later that design became the basis of the GamuT brand.

Key specs that matter

A single M500 delivers 500 W into 8 ohms and 1,000 W into 4 ohms. Its short-term 2 ohm rating of 2,000 W drops to roughly 1,800 W in practice because of mains fusing - two 6.3 A slow-blow fuses restrict long-term consumption to 2,900 W. Each monoblock draws 100 W at idle on 230 V. Inputs are a balanced XLR at 40 kOhm and an unbalanced RCA at 20 kOhm, and every chassis is 485 mm wide, 270 mm high and 535 mm deep.

Engineering and use context

With a dedicated mains transformer in each box, the demand placed on one speaker cannot draw down the supply of the other. The name Fast Linear Ultimate Operation sums up two design goals - output that stays correct at any level and frequency, and output that remains a constant linear multiple of the input. The output device is a single-die semiconductor that FLUO rates at around 450 W, used instead of several paralleled transistors whose small differences would split the current unevenly. The company claims a working bandwidth from 16 Hz to beyond 20 kHz and says it lowers resistance throughout the current path, from the mains transformer and circuit board layout to the capacitors, output devices and internal wiring. Its protection scheme refuses loads under 1.5 ohms and silences the amplifier if temperatures climb past the permitted limit.

Pairing

FLUO pairs its power amplifiers with the PRE1, a dual mono preamplifier built on two independent circuit boards that shares their low-noise power supply technology and measures 0.0002 percent second and third harmonic distortion, 114 dB below the signal. The maker also asks for shielded interconnects to keep external fields from adding noise.

Alternatives

FLUO offers no other single-channel monoblock, as its remaining power amplifiers carry two channels in one chassis.