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Quad II Forty

Monobloc Valve Power Amplifier (2004-08)

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Quad II Forty


The Quad II Forty power amplifier is a direct descendant of the legendary Quad II amplifier designed by Peter Walker, founder of Quad and one of the guiding lights of early Hi-Fi reproduction.

Like the Quad II, the II Forty uses the uniquely simple and timeless circuit topology developed by Walker.

The modern listener demands a higher power output than the 15W of the original Quad II. The new amplifier uses larger output valves and a more robust power supply and the input valves have been upgraded to military grade devices.

Whilst it retains the layout and styling of the Quad II, the chassis size has been increased to take the substantially larger components including mains and output transformers.


Power output: 40W into 8Ω (mono)

Frequency response: 10Hz to 30kHz

Total harmonic distortion: 0.3%

Damping factor: 20

Input sensitivity: 1V

Signal to noise ratio: 80dB

Speaker load impedance: 4Ω to 8Ω

Valve complement: 2 x 6SH7, 2 x KT88, 1 x 5U4G


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