Усилители мощности моно — Audio Research Reference 160M MkII

The Reference 160M MkII is a monoblock vacuum-tube power amplifier from Audio Research, developed over two years and built in Maple Grove, Minnesota. Each chassis drives one speaker, so a stereo system needs two, and its styling was drawn to complement the Reference 6 preamplifier.

Key specs that matter

Each unit delivers 140 W continuous from 20 Hz to 20 kHz, with total harmonic distortion at 1 kHz typically 1% at full power and below 0.04% at 1 W. Power bandwidth runs from 5 Hz to 70 kHz at the 3 dB points, while small-signal response at 1 W extends from 0.5 Hz to 110 kHz. Input sensitivity is 2.4 V RMS balanced for rated output, equal to 25.5 dB of gain into 8 ohms, and balanced input impedance is 200k ohms. Output taps for 16, 8 and 4 ohm loads are fitted. Overall negative feedback is 14 dB, the slew rate is 13 V per microsecond and rise time is 2.0 microseconds. Output regulation is about 0.6 dB from a 16 ohm load to open circuit, which corresponds to a damping factor of roughly 14.

Engineering and use context

Two matched pairs of KT150 output tubes are driven by two 6H30 tubes in the gain stage, and the operator can switch between Ultralinear and Triode operation. A proprietary auto-bias circuit keeps the output tubes at the correct bias and adjusts for tube wear, and it also accepts 6550, KT88 and KT120 types. Output tube monitoring and protection are built in. The signal path uses fewer components than earlier designs, many of them custom made, on a 4-layer circuit board of a kind previously used in the brand's preamplifiers. Power regulation is solid state, and the supply combines a newly developed High Energy Capacity Transformer with a large bulk storage network. A GhostMeter with dual-layer etched markings sits in front of the tubes and acts as a power meter, lit by hidden LEDs with adjustable brightness. A sculpted cover carries a fan for cooling. Inputs come in XLR balanced form and in RCA form for unbalanced sources. Each chassis measures 43.8 cm wide, 25.4 cm high and 47 cm deep, or 48.9 cm with handles, and weighs 25.5 kg net.

Pairing

Consumption is 260 W at idle, 400 W at rated output and 700 W maximum, with 1 W when switched off, on 105 to 130 V or 210 to 250 V mains. Audio Research notes that actual output power depends on line voltage and on how clean the mains supply is, since a distorted power line lowers the maximum. Finishes are Natural silver and Black.

Alternatives

The Audio Research Reference 330M is a monoblock with auto bias, 12 V triggers, RS232 control and 4 and 8 ohm speaker outputs.