Pre/Power Amplifiers

In common with Audio Analogue's recent top-line products, the design of its Anniversary amplifiers has been given over to 'AirTech Labs' – a sub-brand dedicated to AA's product development. This team is responsible for the evolution in AA's amplifier circuit design already witnessed in the Anniversary series of Puccini [HFN Jun '16] and Maestro [HFN May '17] models. Indeed, aside from the retention of the Bellini and Donizetti names, and distinctive casework, AA says these are both ground-up redesigns. Nevertheless, while the use of transconductance gain stages is new here, the over-arching principles of minimum local compensation (feedback), a fully-balanced architecture, a massive and very tightly-regulated PSU, and the ability to drive very difficult loudspeaker loads, is all very familiar.

While 'zero feeback' is seen as an aspirational badge of honour by more than a few audiophile brands, some form of stabilising compensation is required to determine gain (+26dB here), bandwidth and distortion, particularly when tackling the thermal drift of a high-power output stage. AA uses 'relay switches to minimise non-linearity and oversized military resistors to minimise thermal distortion' but whatever the purported subjective benefits of minimal feedback, distortion in the Donizetti is still clearly influenced by output level and temperature [Graph, 1kHz/10W/8ohm; black = left, red = right channel]. PM