AUDIO RESEARCH REFERENCE 75

Pre owned. In good condition. Shows some signs of wear. Original packaging not included.

The Audio Research Reference 75 is a stereo tube amplifier of extraordinary power and refinement, while maintaining a rare simplicity in high-end design. Although it shares the input stages with direct-coupled JFETs and the 6H30 tube with the Reference 110 and 150 models, the Ref 75 stands out for its use of only four Tungsol KT120 output tubes in an ultralinear “partially cathode coupled” configuration, compared to eight in the Ref 150 or eight 6550Cs in the Ref 110. The KT120s, specifically designed for audio applications, offer greater robustness and power, superior dynamics, lower distortion, improved tonal balance, a wider soundstage, and a more pronounced sense of presence.

The oversized power supply, with 520 joules of energy storage like the Ref 110, benefits from improved coupling capacitors and increased damping on capacitors and heatsinks, ensuring absolute stability and quiet operation. The circuit design is straightforward and direct, with extremely short signal paths, highlighting both elegance and internal efficiency. The absence of cooling fans and the lightweight construction of only 21 kg make the Ref 75 the lightest stereo tube amplifier in the ARC range.

Using a single pair of push-pull output tubes per channel allows for superior sonic purity compared to multi-pair configurations, reducing subtle smearing and inaccuracies caused by tube variations or uneven aging. The more powerful KT120s deliver high performance without sacrificing linearity or coherence. The Ref 75 also features two VU meters reminiscent of ARC’s classic D79 amplifiers from the 1970s, which allow precise bias adjustment of each individual tube; the settings remain stable over time, only needing adjustment when moving to a location with different mains voltage or when replacing output tubes.

The amplifier includes 4 and 8 ohm outputs, 12V triggers for input and output, and a robust detachable power cord with a 20A plug. The front panel comes in standard silver, with black available on request. In listening, the Reference 75 impresses with engaging musicality: every detail emerges naturally, the soundstage is wide and well-defined, and the available power easily drives demanding speakers. The combination of authority, dynamics, and transparency makes every listening experience unique, positioning the Ref 75 not just as an amplifier, but as a true musical companion.

Technical specifications:

• Type: tube power amplifier
• Tube complement: four KT120, two 6H30
• Maximum output power: 75 W per channel continuous, 20 Hz–20 kHz (18.75 dBW into 8 ohms)
• Total harmonic distortion (1 kHz): 0.6% at 75 W; 0.05% at 1 W
• Power bandwidth: –3 dB, 7 Hz–60 kHz
• Frequency response at 1 W: 0.7 Hz–75 kHz, –3 dB
• Input sensitivity: 1.4 V RMS balanced for rated output; balanced gain 25 dB into 8 ohms
• Input impedance: 300 k ohms balanced
• Slew rate: 10 V/µs
• Rise time: 4 µs
• Power-supply energy storage: approx. 520 joules
• Dimensions: 48.3 cm (W) × 22.2 cm (H) × 49.5 cm (D); handles extend 3.8 cm
• Weight: 21.3 kg net