Audio Research Reference 160S Stereo Power Amplifier

140 Wpc Ultralinear or 70 Wpc Triode Operation With Auto-Bias, Dual GhostMeters, and Eight KT150 Output Tubes

The Audio Research Reference 160S brings the architecture and feature set developed for the REF160M monoblock into a single stereo chassis. Its fully balanced circuit topology uses eight KT150 output tubes and four 6H30 gain-stage tubes, delivering approximately 140 Wpc in Ultralinear mode or 70 Wpc in Triode mode.

The 160S gives you more than one way to integrate it into a serious system. Balanced XLR and single-ended RCA inputs accommodate a wide range of preamplifiers, while dedicated 4-, 8-, and 16-ohm output taps provide appropriate connections for different loudspeaker loads. A 12 V trigger and RS-232 interface support remote and system-control installations.

Ultralinear or Triode at the Touch of a Button

A front-panel control switches the Reference 160S between Ultralinear and Triode operation. Ultralinear mode provides approximately 140 Wpc, while Triode mode provides approximately 70 Wpc, allowing the owner to choose between the two operating modes without changing tubes or making internal adjustments.

Automatic Bias Control

Audio Research's auto-bias circuit eliminates routine manual bias adjustment. Once factory-set, the circuit continually compensates to maintain the proper bias as the KT150 output tubes age. A front-panel Tube Monitor function provides a convenient way to check the operating status of all eight output tubes.

Dual GhostMeters

Dual GhostMeters place the power-meter displays in front of the eight KT150 output tubes, giving the 160S the distinctive visual architecture introduced with the REF160M. Meter illumination can be adjusted through four brightness levels, including off.

Designed for Real-World System Integration

The Reference 160S includes selectable balanced or single-ended operation, switchable high/low fan speed, and a defeatable auto-shutoff function that turns the amplifier off after two hours without a detected signal. Two internal fans provide forced-air cooling, while the rear panel includes 12 V trigger connections and RS-232 control for integration with automated systems.

Features

• 140 Wpc continuous output from 20 Hz–20 kHz in Ultralinear operation
• Approximately 70 Wpc in Triode operation
• Eight matched KT150 output tubes and four matched 6H30 gain-stage tubes
• Fully balanced circuit topology
• Proprietary automatic bias circuit with continuous compensation as output tubes age
• Switchable Ultralinear and Triode operating modes
• Dual GhostMeter power meters
• Output-tube monitoring for all eight KT150 tubes
• Balanced XLR and single-ended RCA inputs
• 4-, 8-, and 16-ohm speaker output taps
• Four-level meter illumination adjustment, including off
• Selectable high/low fan speed
• Defeatable two-hour auto-shutoff
• 12 V trigger input/output and RS-232 control
• Four-layer circuit board

Included Accessories

• Eight matched KT150 output tubes
• Four matched 6H30 tubes
• 20 A IEC 12-gauge AC power cord
• 7/64" hex driver for initial tube-cage removal

Specifications

Power Output: 140 Wpc continuous from 20 Hz–20 kHz; 1 kHz total harmonic distortion typically 1% at 140 W, below 0.04% at 1 W; approximately 70 Wpc in Triode mode

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: 300k ohms balanced; 100k ohms single-ended

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

Output Taps: 4, 8, and 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: 105–130 VAC, 60 Hz; 875 W at rated output, 700 W in Triode mode, 500 W at idle, 3.6 W off

Tubes Required: Eight KT150 output tubes (four matched pairs); four 6H30 gain-stage tubes

Dimensions (H × W × D): 10.25" x 19" x 21.5" (26 x 48.26 x 54.61 cm); 24" (60.96 cm) deep with handles and connectors

Weight: 100 lb. (45.4 kg)