Musical Fidelity A1
A pure Class A topology rated at 25 watts per channel
Technical Talk
The A1 is built around a completely discrete and symmetrical Class A topology. It‘s able to output 25W of pure Class A power @ 8 ohms load with 25A of maximum output. While the numbers here might seem rather low, the ability for the output stage to drive difficult speakers is a small miracle in itself. The amp design being dynamic class A, and if Class A standing current is exceeded, it will automatically allow more. It therefore “slides” (NOT “switches”) smoothly into class B style operation, temporarily allowing the further current draw needed.
The A1 through time - Improvements to the original
-Updated transformer to more efficient “dual mono split rail” windings
-High quality and updated ALPS RK series potentiometer as volume control
-IR remote control added for volume
-Gain block before volume control totally by passable using “direct” switch (-10dB)
-All transistors including output devices are carefully selected modern equivalents
-All capacitors in signal path are polypropylene (PP) type
-Resistors are modern low noise metal film types
-Care and attention made to not change any component specification from original but to update them to modern equivalent with long lifespan
-Layout faithfully follows original within circuit sections on circuit board
-Circuit sections better laid out, in particular the separate supplies and power amplifiers
-Phono stage and preamplifier improved for less noise and hum