Masterclass ANV-50

The Sugden Masterclass ANV-50 is an integrated amplifier developed for Sugden Audio’s 50th anniversary. It follows the company’s history in solid-state pure Class A amplification, which began in 1967 with the A21, described by Sugden as the world’s first solid-state pure Class A amplifier. The ANV-50 applies this approach to the requirements of current audio systems and listeners.

At the centre of the Sugden Masterclass ANV-50 is the purest Class A amplifier Sugden Audio has produced, combined with an advanced ‘ideal’ final output stage. This 2-stage amplification system retains Sugden’s pure Class A circuit while providing the drive required by most loudspeaker systems.

The final output stage uses a comparator and correction circuit to correct errors in the power output section caused by varying loads and distortion. Its output is matched to that of the high-impedance input amplifier, preserving signal authenticity while improving load stability and forcing the output impedance to zero. Sugden Error Correction gives the output stage an extremely low open-loop output impedance and a high damping factor at quite high frequencies. The design also uses overall Current-Feedback.

The power amplifier and pre-amplifier are fully DC coupled, with no capacitors in the signal path. The ANV-50’s Class A power supply provides high standing current and power reserves, keeping the output ready to respond to each signal. Instead of relying on a conventional Class AB amplifier to receive power through a transformer and bridge rectifier, it uses a 1 MHz switching power supply that delivers power instantly while the Pure Class A amplifier section remains continuously on.

Its power supplies are high-current, fast and stable, with an MTBF (Mean Time Before Failure) of 100 years. The internal pre-amplifier was developed specifically for the ANV-50. It uses a line-drive circuit with the minimum number of high-quality components, providing an open and natural sound through a straightforward signal path.

With no input signal, the Sugden Masterclass ANV-50 consumes 20 Watts. Its heatsinks are mounted internally and have minimum contact with the outer case, so the amplifier runs only slightly warm to the touch.

The ANV-50 delivers 50 Watts into 8 Ohms, with this output able to double into lower impedances. This makes room size and loudspeaker sensitivity less restrictive when matching the amplifier to loudspeakers.