Audio Research Reference 160M MkII Monoblock Power Amplifier

140 Watts of Reference-Series Tube Power With Switchable Ultralinear/Triode Operation, Auto-Bias, and the Signature GhostMeter

The Reference 160M MkII is a central pillar of Audio Research's Reference amplifier range, combining 140 W of continuous monoblock power with a refined signal path, switchable Ultralinear/Triode operation, proprietary auto-bias, and comprehensive output-tube monitoring and protection.

Each monoblock uses four KT150 output tubes, while a newly developed High Energy Capacity Transformer and substantial bulk storage-capacity network are designed to provide high current on demand. Audio Research's approach pairs this robust power supply with a deliberately short audio path built around a four-layer circuit board and selected high-grade and custom components.

Ultralinear or Triode Operation

The Reference 160M MkII allows the user to switch between Ultralinear and Triode operation, providing two distinct operating choices from the same amplifier. The feature is integrated into the amplifier's broader control and protection architecture rather than requiring manual reconfiguration of the output stage.

Automatic Tube Bias

Audio Research's proprietary auto-bias circuit continuously maintains output-tube bias and compensates as the tubes wear, eliminating routine manual bias adjustment. In addition to the supplied KT150 output tubes, the circuit is designed to work with 6550, KT88, and KT120 tube types.

GhostMeter Display

The distinctive GhostMeter provides a clear view of the output tubes while incorporating a power-output meter directly into the front-panel presentation. Etched markings form part of the integrated display, and its brightness is adjustable to suit the room.

High-Energy Power Supply and Short Signal Path

The power supply incorporates Audio Research's High Energy Capacity Transformer and a large bulk storage-capacity network intended to provide the current reserves required for demanding transient peaks. A four-layer circuit board supports the amplifier's short signal path and its selection of high-grade and custom-made components.

The Reference 160M MkII is available in Natural (Silver) or Black finishes.

Features

• 140 W continuous monoblock output from 20 Hz–20 kHz
• Switchable Ultralinear/Triode operation
• Proprietary automatic output-tube bias system
• Output-tube monitoring and protection
• Four KT150 output tubes per monoblock
• Compatible with 6550, KT88, and KT120 output tubes through the auto-bias system
• High Energy Capacity Transformer with substantial bulk storage capacity
• Four-layer circuit board supporting a short signal path
• GhostMeter with integrated power-output display and adjustable brightness
• Balanced and single-ended inputs
• 4-, 8-, and 16-ohm output taps
• Available in Natural (Silver) or Black finishes

Specifications

Power Output: 140 W continuous from 20 Hz–20 kHz

Total Harmonic Distortion (1 kHz): Typically 1% at 140 W; below 0.04% at 1 W

Power Bandwidth (-3 dB Points): 5 Hz–70 kHz

Frequency Response (-3 dB Points at 1 W): 0.5 Hz–110 kHz

Input Sensitivity: 2.4 V RMS balanced for rated output; 25.5 dB gain into 8 ohms

Input Impedance: 200k ohms balanced; 100k ohms single-ended

Output Polarity: Non-inverting; balanced input pin 2+ (IEC-268)

Output Taps: 4, 8, 16 ohms

Output Regulation: Approximately 0.6 dB, 16-ohm load to open circuit; damping factor approximately 14

Overall Negative Feedback: 14 dB

Slew Rate: 13 V/microsecond

Rise Time: 2 microseconds

Power Requirements per Monoblock (US): 105–130 VAC, 60 Hz; 400 W at rated output, 700 W maximum, 260 W at idle, 1 W off

Output Tubes per Monoblock: 2 matched pairs KT150 (V1–V4)

Dimensions (H × W × D): 10" x 17.25" x 18.5" (25.4 x 43.8 x 47 cm)

Depth With Handles Extended: 19.25" (48.9 cm)

Shipping Weight per Monoblock: 73 lb. (33.2 kg)

Weight per Monoblock: 56 lb. (25.5 kg)