t's difficult to improve upon well-regarded audio electronics each time out, but Audio Research does it -- definitively. The latest amplifier in Audio Research's Reference series, the Reference 150 ($12,995), has the especially unenviable task of replacing the Reference 110, one of the most respected contemporary stereo tube amplifiers. The Reference 150 offers greater power -- 150Wpc versus 110 -- and quieter operation, due to a redesign of its cooling fans. In terms of performance, Audio Research claims "greater dynamic thrust, a more vivid and resolved presentation, [and] greater finesse" for the Reference 150.
The two amplifiers share the same dimensions, but the Reference 150 has more packed within its chassis, including larger wide-bandwidth output transformers. Power-supply energy storage has been doubled to 1040 joules, and new interstage coupling capacitors are used. These utilize technology and materials first incorporated in Audio Research's Anniversary preamplifier, and they link the Reference 150's input stage to its output stage, where 6H30 twin triodes drive matched quads of Russian KT120 output tubes. The output stage employs a combination of ultralinear and Audio Research's patented "partially cathode-coupled" topology, which is said to be "superior to conventional pentode or triode operation."
Like the Reference 110, the Reference 150 is fully balanced, so it has only XLR inputs. Outputs for 4-, 8-, and 16-ohm speaker loads are included. The amp's power connection is via a 20A IEC. Both channels have their own three-speed cooling fans, which now feature low-turbulence intakes for quieter operation. Cosmetics follow the current Audio Research style, with all-silver, all-black, and mix-and-match options.
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