Sugden has released a pure Class-A headphone amplifier, the Masterclass HA-4 that it claims: ‘extends the boundaries of near-field listening to a level of musical performance that is truly amazing.

Sugden amplifiers are synonymous with Class-A, because this UK company produced the first commercially-available Class-A transistor amplifier in 1964; the Sugden A21. Sugden’s line-up continues to have predominately Class-A designs and nearly 50 years later the A21 is still in production, though now known as the A21a Series 2. Sugden released its first dedicated headphone pre-amplifier, the Bijou HeadMaster, in 1999. ‘The HeadMaster quickly became very sought after due to its handmade solid aluminium construction and musical performance,’ said George Neophytou of Neophonics, which distributes Sugden in Australia. ‘The head-fi forums rattled with commentary and praise.

The circuit inside the new Masterclass HA-4 is a variation of the circuit inside Sugden’s pre-amplifier and consists of a high input impedance voltage-to-current converter, variable current source and a current-to-voltage conversion stage. The final current-to-voltage conversion stage is based on current feedback in line with the other stages. The pure Class-A MOSFET output stage uses no negative feedback output. ‘This configuration ensures absolute minimum loss of input information due to the high impedance, perfect current gain without attenuation problems and matched sound structure,’ says Neophytou. ‘And whilst the circuit concept is technically superb the final balance of musical performance is achieved by the use of high-quality components, gold-plated circuit boards and silver-soldered circuit construction.

Sugden’s HA-4 casing is a composite of aluminium and steel, using both with anodised and powder-coated surface treatments. Available now, it retails in Australia for $2,595 and comes with a three-year warranty.

For further information, please contact Neophonics

altPictured Above: The Sugden Masterclass HA-4 Pure Class-A Headphone Amplifier, distributed in Australia by Neophonics.