405

About the 405

The Quad 405 is a classic power amplifier featuring Quad's patented 'Current Dumping' technology, which uses a low-powered class-A amplifier to control the output of high-powered transistors, minimizing distortion and crossover issues common in solid-state amps. It delivers 100 watts per channel into 8 ohms with a frequency response of 20Hz to 20kHz and very low total harmonic distortion (0.05%). The amplifier is compact and heavy for its size, measuring 115 x 340.5 x 195 mm and weighing 9 kg. It is praised for its smooth, warm, and fatigue-free sound, making it ideal for long listening sessions. The design prioritizes speaker protection, especially for Quad electrostatic speakers, which results in less bass extension below 45-50Hz. The Quad 405 is highly serviceable and reliable, though original units may require maintenance due to age. It uses DIN connectors and lacks a power switch on the unit itself. The amplifier is well-suited for use with efficient speakers and bi-amped systems with subwoofers for extended bass. The 405-2 is an improved version with higher power handling and better protection circuitry.