About
The Quad 405 Mk2 was bought in 1983 to replace the Goodmans Module Ninety amplifier, which had been used to power the Goodmans Achromat Speakers. The amplifier was bought together with the Quad 34 pre amp, shown here on top of the 405.
How it works
The amplifier used a technique called current dumping to amplify the sound input. This is achieved by combining a high quality, low volume circuit, and a high volume low quality circuit. These two circuits are then combined to generate a high quality, high output circuit which is both reliable and safe.
The downside however is that the Class A circuit design uses a large amount of power, the energy of which is transferred as heat on the large metal heat sink on the front of the unit.
Where is it now?
The amplifier is still in use, powering my own hi-fi system. Although not designed to be used with CD players, the amplifier can produce clear robust sound through a pair of modern Quad 11L speakers.
