Усилители мощности стерео — Fm Acoustics 1811-MKII

The FM 1811-MKII is the Resolution Series stereo power amplifier from FM Acoustics, built by hand to special order at the company's facilities in Switzerland. Every unit goes through multiple pre- and final tests carried out by three different engineers, after a factory burn-in of at least 100 hours (500 thermal cycles) and a vibration test of at least 60 minutes.

Key specs that matter

Guaranteed minimum output per channel, both channels driven, is 500 W RMS into 8 ohm, 1000 W RMS into 4 ohm and 1700 W RMS into 2 ohm, with 1000, 2000 and 3400 W peak into the same loads and a repetitive impulse rating of 4600 W per channel. Maximum output voltage is 184 Vpp and continuous output current exceeds 80 A per channel. Gain is 30.1 dB, rise time at full power is 3 us, maximum input level is +20 dBm and interference rejection is better than 95 dB. The chassis measures 445 x 275 x 530 mm and weighs 47 kg net.

Engineering and use context

The input uses proprietary electronically balanced discrete class A circuitry in non-inverting or inverting mode, and single-ended sources are balanced automatically right at the inputs. New symmetrical input modules feed high-linearity driver stages. The design uses no fuses and no form of current or voltage limiting, and the maker specifies no minimum load, from below 1 ohm to above 10,000 ohm, covering dynamic, electrostatic, ribbon and planar speakers. An on-board system monitors short circuit, open circuit, HF oscillation, RF interference, DC offset of either polarity, parasitic frequencies and over-temperature. A dual chassis with supplied tuned anti-resonance isolators handles resonances, and the layered transformer alone weighs 21 kg. Consumption is 200 W at idle, 1400 W at 30% power and 3600 W at full power. Hum and noise are typically 115 dB below full power, and at least 100 dB unweighted. Spare parts are guaranteed for at least 10 years, and average life expectancy is quoted as 40 years at 10 hours a day.

Pairing

The amplifier needs a dedicated ultra low-impedance mains line able to supply 16 A continuous and 65 A peak at 230 V, or 32 A continuous and 130 A peak at 120 V. Speaker outputs are FORCEPLUG 200 connectors rated at 1200 A peak, and the maker requires its FORCELINES 3 speaker cables to be used with them.

Alternatives

FM Acoustics also makes the FM 711-MKIII precision power amplifier in the same Resolution Series.