Audio Analogue CLASS A SE (Demo)

State of The Art. CLASS "A" Integrated Amplifier

The preamplifier power supply is stabilized using discrete components linear regulators. The first amplification is before the attenuator to optimize the coupling with the source. The input stage of the preamplifier is realized with two low noise bipolar transistor (MPSA18). The internal stages are DC coupled and the offset is reduced by means of an integrating amplifiers.

The input attenuator is realized with two cascaded integrated resistance network without integrated output buffer. High current capability.

The protection and control sections are galvanically insulated from the analog sections to minimize the digital noise. No mains fuse. The mains current is measured at the input of the transformer (with a current probe) and in case of malfunctions it's shutted off. The voltage of both channel is measured by means of optocoupler to avoid any ground loop.

The DC offset on the output (loudspeakers) is also monitored by means of optocouplers. The protections are realized with a Programmable Logic Device (PLD), more fast and reliable if compared to a microcontroller.

Features:

• Two toroidal, 400VA transformer, one per channel.

• Dual mono design. Pure class A operation up to 50W at 8 Ohm.

• Only double-sided metallized polypropylene film capacitor in the signal path.

SPECIFICATIONS