Musical Fidelity A1 2023

Musical Fidelity A1 - Amplifier with 2 x 25 pure Class A watts, RIAA amplifier, high-quality power supply and advanced preamplifier design

Musical Fidelity A1 has become one of the most classic designs in the Hi-Fi world - both inside and out. It was first launched back in 1988 and quickly made an impression by being an absolute powerhouse when it came to driving some of the most demanding speakers of the time, even though it was actually a relatively low-powered integrated amplifier. But it was all done in pure Class A with an outstanding and expertly laid-out discrete symmetrical circuit topology, using only components of the highest quality. A1 showed people that amplifiers were more than just high power.

Based on its enormous success, A1 has gone through several reissues and new versions over the years. Now in 2023, Musical Fidelity has finally chosen to retain all the original specifications, appearance, and circuitry from the original 1988 version, for those who missed it the first time around. With an updated transformer, power supply, and modern low-noise components, we have recreated the formula and are proud to reintroduce the fresh original product - three decades later.

Highlights

• 2 x 25W pure Class A power at 8 ohms
• Discrete symmetrical topology
• Drives difficult speakers without problems
• Updated transformer with "dual mono split rail" windings
• Fully independent left and right power supplies
• Each amplifier stage now has double current capacity
• Reduced transformer noise and heat dissipation
• Low-noise preamplifier circuitry
• Discrete current-driven MM/MC phono input stage
• Low-noise current-to-voltage conversion for additional amplification and RIAA correction
• Automatic impedance matching (1K nominal) for MC as well as increased gain

A dynamic Class A amplifier

A1 is built around a fully discrete and symmetrical Class A topology. It is capable of delivering 25W of pure Class A power into an 8-ohm load with a maximum output current of 25A. Although these figures may seem rather low, its ability to drive demanding speakers is a small miracle in itself. The amplifier's design is dynamic Class A, and if the current required for Class A operation is exceeded, it automatically allows more current. It therefore "glides" seamlessly into Class B-style operation to temporarily allow the additional current draw required.

High-capacity power supply

The new A1 has received an updated transformer, moving from the previous split design (1988 original) to more efficient "dual mono split rail" windings. The amplifier stages are powered by fully independent left and right power supplies for better current handling and stereo imaging, and each power amplifier now has double current capacity, resulting in reduced ripple and noise. Transformer noise and heat dissipation have been reduced thanks to better efficiency and updated components. The primary power supplies are filtered for better regulation and reduced switch-on surge.

An advanced preamplifier design

The low-noise preamplifier circuitry is the same as in the original 1988 design and, as we mentioned earlier, benefits greatly from the improved, fully smoothed and regulated power supplies. One of the clear changes that immediately stands out is the addition of a new "direct" button in the preamplifier stage. With this button, you can completely bypass the gain stage before the volume control, resulting in approximately 10 dB less gain. This feature is especially beneficial when working with modern or high-output digital sources, as it allows fine adjustment of the volume potentiometer's range and the ability to adapt to sensitive speakers. In addition, a remarkable upgrade has been made to the volume potentiometer itself, which has now been replaced with a premium ALPS RK-series potentiometer. This high-quality component ensures superior performance and improved precision. In addition, the potentiometer is now motorized, giving you the convenience of adjusting the volume from the comfort of your sofa thanks to the new included remote control.

Built-in RIAA amplifier for MC and MM cartridges

A1 uses a discrete current-driven input stage for the lowest possible noise amplification of MC and MM cartridges. A low-noise current-to-voltage conversion stage is used for additional amplification and RIAA correction. Automatic impedance matching for the selected MC input and increased gain enhance the versatility of A1's phono stage.

The true Hi-Fi classic returns

A1 has a secret. This secret is simple: It creates music. It sounds sweet and fluid and creates a beautiful atmosphere around natural instruments. Especially in small to medium-sized rooms carefully arranged with a pair of fantastic two-way speakers. It is not a powerhouse, but music lovers will appreciate its abilities. Nor is it a product you will want to hide. A perfect example of form follows function. The oversized heatsinks define A1's appearance, but they are crucial to its function. Truly unique, both outside and inside. A1 has a sweet, warm, full-bodied and exciting sound. No harshness. No graininess. Just pure music. It does not become muddy, and despite its lower power, it drives difficult speakers with ease. It remains clean right up to its power limit. Hearing what A1 can do is hearing what Hi-Fi should be able to do: It creates music, pure and simple.

Improvements to the original A1

• Updated transformer with more efficient "dual mono split rail" windings
• High-quality and updated ALPS RK-series potentiometer as volume control
• Added IR remote control for volume adjustment
• The gain stage before the volume control can be completely bypassed using the "direct" button (-10 dB)
• All transistors, including output components, are carefully selected modern equivalents
• All capacitors in the signal path are polypropylene (PP) type
• Care and attention have been taken not to change any component specifications from the original, but to update them to modern long-life equivalents
• The layout faithfully follows the original within the circuit sections on the circuit board
• Circuit sections are better organized, especially the separate power supplies and power amplifiers
• The phono stage and preamplifier have been improved to reduce noise and hum