AA 4AI Integrated amplifier

The Audio Alto 4 series reflects the extra effort and know-how in amplifier design, as it presents a quite different solution with built-in vacuum tubes. The result of this new design and construction is its elegant shape and the special design of the amplifier stages. The sound that is the result of a design without a global feedback loop, using local fast corrections, a design that represents the red thread of Audio Alto concepts, allows accurate, pleasant and natural reproduction of all genres of music.

The AA 4AI is an integrated amplifier. The amplifier has a modular design, allowing the insertion of various input modules (e.g. Phono RIAA MM/MC, etc.). The AA 4AI power supply is realized by a 150VA toroidal transformer with an electrostatic and magnetic shield. The supply voltage and the heating of the electronic tubes is time-controlled for optimal operation and to extend their lifetime (even more than 4000 hours). The unit has a built-in digital time display showing the vacuum tubes elapsed time in hours.

All amplification stages operate in class A or in “moving” class A. The input assemblies are realized with low-noise circuits with extremely small harmonic distortions. The AA 4AI uses two special amplifying tertrodes, the operating point of which is defined by the current source. The vacuum tubes are NOS manufactured by Telefunken from the 60s/70s. The selected 829B (SR4451/3) tube is a very robust dual tertrode that provide low input capacitance, low voltage driving requirements, high operating current, low output impedance and very low distortion levels, even without a negative feedback.

The AA 4AI is handcrafted and all components are tested before assembly.