Audio Analogue "Maestro Anniversary" integrated amplifier

Integrated Amplifier

The Maestro Anniversary was born in AIRTECH laboratories following the experience gained with the development of the Puccini Anniversary. The basic scheme is very similar but with one fundamental difference: the amplification chain is completely balanced from the input to the power stage and then unbalanced again before connecting to the speakers. This results in a doubling of both the amplification and attenuation stages.

Like the Puccini Anniversary, every stage of the Maestro Anniversary operates with zero global feedback. Feedback is not used in the preamplifier stages either. Output power has been increased to 150W into 8Ω, requiring redesigned driver and output stages using four transistor pairs per channel. The basic configuration remains an inverted cascode followed by an output buffer.

The operating point stability is maintained by a DC Servo circuit that operates only at frequencies below a few tenths of a Hertz, completely outside the audio band. Together with carefully selected components—including military-grade resistors, AIRTECH-specified audiograde polypropylene capacitors, 7N OCC pure copper internal wiring and gold-plated pure copper output connectors—this refined circuitry creates a worthy successor to the legendary Maestro Integrated.

The Maestro Anniversary is a unique amplifier. Its impressive output power, which doubles as impedance decreases, exceptional speaker control, musicality and refinement distinguish it from conventional high-power amplifiers.

Key Features

• Fully balanced amplification chain from input to power stage.
• Zero global feedback design throughout both amplifier and preamplifier stages.
• 150W per channel into 8Ω with four transistor pairs per channel.
• Inverted cascode amplifier topology followed by an output buffer.
• DC Servo circuit for operating point stability.
• Fully dual-mono construction with separate power supplies and grounding.
• Dual 600VA transformers, one dedicated to each channel.
• RR version available with relay- and resistor-based analog volume attenuation.

Technical Description

The amplifier is designed as three separate sections: power supply, power amplifier and preamplifier.

The power supply uses one 600VA transformer per channel, ultra-fast 50A discrete rectifier diodes and a total filtering capacity of 67,200µF. Inrush current is limited at power-on by temperature-dependent resistors that are subsequently removed from the signal path.

The amplifier section features a fully dual-mono design with separate grounding and power supplies. The digital volume control stages are optocoupled, while PCB copper tracks are twice the standard thickness and routing is optimized to preserve signal symmetry.

The preamplifier section is also dual-mono. Channel switching relays are located directly behind the inputs, followed by a discrete buffer stage. Maximum input voltage is approximately 6VRMS. Class A buffers drive four volume control chips per channel, consisting only of resistor strings without operational amplifiers, eliminating any form of global feedback. The preamplifier stage then provides approximately 12dB of gain.

The three sections are physically separated onto individual circuit boards, effectively creating separate power supply, preamplifier and power amplifier sections. The Maestro Anniversary is also available in RR version with analog relay- and resistor-based volume attenuation for even higher sound performance. Available in natural aluminium and satin black.