QUAD 405-2

Pre owned. In good condition. Shows some signs of wear. Without original packaging.

The Quad Electroacoustics 405-2 is a stereo power amplifier that represents one of the most innovative and appreciated creations in the history of the British Quad brand. Designed by Peter Walker, the company’s founder, it was developed with the aim of achieving extremely precise, reliable and musical amplification through an original technical approach based on design simplicity and the elimination of unnecessary complexity.

The heart of the design is the revolutionary Current Dumping circuit, a technology developed by Quad to combine the linearity and sonic refinement typically associated with sophisticated amplification systems with the robustness and efficiency of transistor power stages. This system allows the main control stage to operate with extreme precision, while a dedicated power stage provides the current required to drive loudspeakers. The result is exceptionally low distortion, natural dynamic response and a reproduction characterised by balance, transparency and outstanding musicality.

The Quad 405-2 delivers approximately 100 watts per channel into 8 ohms, providing sufficient power reserves for most Hi-Fi systems of its era while still being capable of driving quality loudspeakers with authority today. The design is engineered to remain stable even with demanding loads, thanks to an advanced protection system that activates in the event of short circuits or abnormal operating conditions, limiting current delivery and preserving the integrity of the internal components.

The construction fully reflects the Quad philosophy, based on functionality and engineering precision. The compact chassis features an extremely understated appearance, free from unnecessary decorative elements or controls. The front panel includes only a red LED indicator showing operating status, while power management and system operation are handled through the simplicity of the design. This minimalist approach makes the 405-2 a discreet and timeless component, easily integrated into any listening environment.

The connection system was designed to ensure perfect integration with Quad equipment of the same generation, particularly with the Quad 44 preamplifier, through DIN connections and coordinated power management. However, thanks to the quality of its amplification stage, the 405-2 can also be paired with preamplifiers from other manufacturers, making it a versatile solution for both modern and vintage Hi-Fi systems.

During listening sessions, the Quad 405-2 stands out for its balanced, refined and natural sound character, with a particular ability to reproduce musical dynamics without harshness. Its sonic signature combines precision and smoothness, offering detailed yet always enjoyable reproduction, with a rich midrange and a stable soundstage. The Current Dumping technology provides extremely linear behaviour while preserving the musicality that has made Quad electronics so highly regarded.

The Quad 405-2 therefore represents a true classic of British amplification, combining technical innovation, reliability and a design philosophy that remains relevant today. A power amplifier intended for enthusiasts seeking a component with a strong character, built according to strict engineering principles and still capable of delivering high-level musical performance many years after its introduction.

Technical specifications:

• Distortion (8 Ω load, sine wave signal, 100 W output): ≤ 0.01% at 100 Hz; ≤ 0.01% at 1 kHz; ≤ 0.01% at 10 kHz
• Internal output impedance: 3.3 µH; 0.03 Ω per channel
• DC offset voltage: ≤ 7 mV
• Frequency response (reference 1 kHz): -1 dB at 20 Hz (bass); -0.1 dB at 20 kHz; -3 dB at 50 kHz (treble)
• Input sensitivity: 0.5 V (8 Ω load, 100 W output)
• Input impedance: 20 kΩ // 220 pF
• Slew rate: 0.1 V/µs
• Maximum input level: +20 dB (with immediate recovery)
• Crosstalk (with 1 kΩ source impedance): 80 dB at 100 Hz; 70 dB at 1 kHz; 60 dB at 10 kHz
• Signal-to-noise ratio: 96 dB (A-weighted); 93 dB (unweighted)
• Power supply: 100–130 V; 200–250 V; 50–60 Hz
• Dimensions (W x H x D): 340.5 x 115 x 195 mm
• Weight: 9 kg