PI Greco A-1000X made by AM Audio.
A-1000X has been conceived to establish a reference point in their category, providing high power and an outstanding music reproduction quality.
A-1000X is a balanced amplifier consisting of two symmetrical amplification
circuits. The input amplification stage of this power amplifier only uses two active components: the first MOSFET (2SK214) covers the whole voltage gain required, while the second one (2SJ77), features only a current gain, ensuring a low impedance output. As in all PIGRECO’s power amplifiers, the final stage provides a both current and voltage amplification.
This power amplifier employs 20 pairs of selected MOSFETs for each sub-amplifier, for a total of 80, which are able to deal with steady currents of 140 Amperes and to dissipate 8kW at 20 °C.
Electrical paths are as short as possible: two IR 36A/400V diode bridges, attached and dissipated to the frame, are connected to the 3000 VA transformer. The toroidal transformer has been manufactured with great care and resin-coated inside the large, 2 mm-thick, polished and chrome-plated black steel container, which is insulated, by means of 12 vibration dampers, from the 3 mm-thick steel frame. The frame is laser-cut and reinforced with 12x20 mm aluminum bars.
Filtration is obtained through various stages, using several parallel electrolytic capacitors providing 120,000, 8.200, 5.600, 2.200 and 47?F respectively, and polypropylene capacitors providing 100 ?F, for a to tal of 1.2 Farads for each monophonic power amplifier.
The input circuits power supply is filtered and stabilized independently, in order to avoid any interference with the power stage, while 3 additional independent secondary circuits feed the low start, loudspeaker protection and bias reduction circuits. All the electronics is installed on nine fiberglass, 2.4 mm thick, double-sided printed circuit boards, featuring 120 micron thick copper paths, complying with military standards.
This power amplifier uses only top-quality components: 1% metal layer resistors, PP and PS capacitors, Cermet trimmers, relays with golden contacts, power resistors complying with military standards, IR diode bridges and selected Toshiba, Motorola and Hitachi active components.
From the aesthetics point of view, this device, for the most part, reminds of the preamplifiers design, since the machining processes employed are the same; however, some decorative elements have been added, such as the lower MOSFET banks, tilted in order to improve their aesthetic effect, the rear and front nameplate, made of black Plexiglas and reverse engraved, the chrome plated inserts of the heat sinks and the black chrome plated sub-base. The aluminium cover fits into a frame of rounded profiles continuing, as in the preamplifier, the front panel design line.
