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AM Audio Amps
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P-1X preamp at €28250.
From AM Audio - "The main structure (P-1X) is a stereo dual mono balanced pre-amplifier equipped with a blue OLED display and a 4-sections R2R-type relay-based potentiometer featuring 501 0,2 db steps ranging from -99.8 to 0 dB.
This device can also control a second optional unit (6X), featuring 6 balanced channels and 12 R2R potentiometers which can be adjusted using the main volume control. All this results in a HT 7.1 all-balanced system with an overall weight of “only” 45+45 kg.
All the 8 channels use the same signal amplification circuit as well as the same power supply circuit pattern, though the circuits have different dimensions.
The amplification circuit consists of two stages made of 3 MOSFET active components: the first stage uses a 2SK214 MOSFET and covers the whole voltage gain required, while the second one, made of two 2SJ77 MOSFETs, features only a current gain, ensuring a very low impedance output. The most suitable components for this kind of design are the middle-power Hitachi MOSFETs: they can operate at relatively high voltages, thus using the region of maximum linearity.
The circuit features zero feedback; the first stage gain varies according to the “sound” and “drain” resistance values, resulting in a reduced local reaction, thanks to the low inherent gain typical of this kind of MOSFETs.
The P-1X power supply section is the most impressive one ever integrated into a preamplifier. Four 100 VA transformers, resin-coated in two chrome-plated aluminium containers, serve 5 different voltage rectifying and stabilizing stages.
The power supply stages of the two amplification circuits rely on the filtering capacity provided by 8 Nippon Chemi-Con 56,000MF, 63V electrolytic capacitors, 8 8,200MF capacitors, 4 5,600MF capacitors and 24 470 MF capacitors, for an overall filtering capacity of 547,280MF. "
From AM Audio - "The main structure (P-1X) is a stereo dual mono balanced pre-amplifier equipped with a blue OLED display and a 4-sections R2R-type relay-based potentiometer featuring 501 0,2 db steps ranging from -99.8 to 0 dB.
This device can also control a second optional unit (6X), featuring 6 balanced channels and 12 R2R potentiometers which can be adjusted using the main volume control. All this results in a HT 7.1 all-balanced system with an overall weight of “only” 45+45 kg.
All the 8 channels use the same signal amplification circuit as well as the same power supply circuit pattern, though the circuits have different dimensions.
The amplification circuit consists of two stages made of 3 MOSFET active components: the first stage uses a 2SK214 MOSFET and covers the whole voltage gain required, while the second one, made of two 2SJ77 MOSFETs, features only a current gain, ensuring a very low impedance output. The most suitable components for this kind of design are the middle-power Hitachi MOSFETs: they can operate at relatively high voltages, thus using the region of maximum linearity.
The circuit features zero feedback; the first stage gain varies according to the “sound” and “drain” resistance values, resulting in a reduced local reaction, thanks to the low inherent gain typical of this kind of MOSFETs.
The P-1X power supply section is the most impressive one ever integrated into a preamplifier. Four 100 VA transformers, resin-coated in two chrome-plated aluminium containers, serve 5 different voltage rectifying and stabilizing stages.
The power supply stages of the two amplification circuits rely on the filtering capacity provided by 8 Nippon Chemi-Con 56,000MF, 63V electrolytic capacitors, 8 8,200MF capacitors, 4 5,600MF capacitors and 24 470 MF capacitors, for an overall filtering capacity of 547,280MF. "
