Audio Research Reference 330M Monoblock Power Amplifier

330 W of Fully Balanced, All-Tube Reference Power With Automatic Bias and KT170 Output Tubes

The Reference 330M is Audio Research's flagship monoblock power amplifier and the culmination of more than 50 years of vacuum-tube amplifier design. Rated at 330 W, it combines substantial output capability with an all-tube signal path, beginning with an ECC83 input stage and culminating in six KT170 output tubes per monoblock.

Audio Research describes the Reference 330M as the finest amplifier it has created. Its architecture combines a fully balanced circuit with tube regulation in the power supply, while both balanced XLR and single-ended inputs make it practical to integrate into a wide range of reference systems. Separate 4-ohm and 8-ohm output taps accommodate different loudspeaker loads.

High Power Without the Usual Tube-Amp Fuss

Automatic bias continuously maintains the output tubes' operating conditions, eliminating routine manual bias adjustment. Audio Research specifies output-tube life at 3,000 hours, while an onboard tube-hour meter and tube-monitoring system help owners keep track of operation and maintenance.

The Reference 330M also provides adjustable fan speed, meter illumination that can be dimmed or switched off, and a meter-action control that can stop the meter needle when desired. A defeatable auto-off function shuts down the amplifier after two hours without a detected signal.

Built for Integrated Reference Systems

For system control, the Reference 330M provides 12 V trigger operation and RS-232 control. The trigger input allows the amplifier to power up along with a Reference preamplifier or compatible master-control system, while standby mode provides a convenient power-saving state.

Features

• 330 W monoblock power output
• Fully balanced amplifier design with an all-tube signal path
• Six KT170 output tubes per monoblock
• ECC83 and 6H30 input tubes
• 6550 and 6H30 tubes in the power supply
• Automatic tube biasing
• 3,000-hour specified output-tube life
• Balanced XLR and single-ended inputs
• 4-ohm and 8-ohm speaker output taps
• 12 V trigger control
• RS-232 control
• Defeatable two-hour auto-off function
• Adjustable fan speed
• Tube-hour meter and tube monitoring
• Adjustable meter illumination
• Switchable meter-needle action
• Standby mode

Specifications

Power Output: 330 W

Tube Biasing: Automatic bias

Output Taps: 4 ohms, 8 ohms

Power Output Tubes: (6) KT170

Input Tubes: (1) ECC83, (1) 6H30

Power Supply Tubes: (1) 6550, (1) 6H30

Inputs: XLR, single-ended

Controls: 12 V triggers, RS-232 remote control

Power Saving: Standby mode

Weight: 101 lb. (45.8 kg)