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

The Musical Fidelity A1 has become one of the most classic designs in the Hi-Fi world - both inside and out. First launched back in 1988, it 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 weak integrated amplifier. But it was all done in pure Class A with an excellent and expertly laid out discrete symmetrical circuit topology and using only the highest quality components. The A1 showed people that amplifiers were more than just high power.

Based on its huge success, the A1 has gone through several re-releases and new versions over the years. Now in 2023, Musical Fidelity has finally chosen to keep all the original specs, looks and circuitry of 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 symmetric topology
• Drives difficult speakers without problems
• Updated transformer for "dual mono split rail" windings
• Fully independent left and right power supplies
• Each amplifier stage now has double the current capacity
• Reduced noise and heat release from transformer
• Low noise preamp circuit
• Discrete current control 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

The A1 is built around a completely 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. While the numbers here may seem rather low, the ability to drive demanding speakers is a small miracle in itself. The amplifier design is dynamic class A and if the current required for class A operation is exceeded, it will automatically allow more current. It therefore "slips" seamlessly into Class B-style operation to temporarily allow the additional current draw that is needed.

High capacity power supply

The new A1 has received an updated transformer from the previously split (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 power handling and stereo imaging, and each power amplifier now has double the current capacity, resulting in reduced ripple and noise. The transformer's noise and heat output are reduced thanks to better efficiency and updated components. The primary power supplies are filtered for better regulation and reduced ignition surge.

An advanced preamplifier design

The low noise preamp circuit is the same as the original 1988 design and, as we mentioned earlier, benefits greatly from the improved, fully smoothed and regulated power supplies. One of the obvious changes that immediately catches the eye is the addition of a new "direct" button in the preamplifier stage. This knob allows you to completely bypass the gain stage before the volume control, resulting in approximately 10 dB less gain. This feature is particularly beneficial when working with modern or high-output digital sources, as it provides fine-tuning of the volume potentiometer range and the ability to adapt to sensitive speakers. Additionally, a notable upgrade has been made to the volume potentiometer itself, which is now replaced by 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 couch thanks to the new included remote control.

Built-in RIAA amplifier for MC and MM pickups

The A1 uses a discrete current control input stage for the lowest possible noise gain of the MC and MM pickups. 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 increase the versatility of the 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 that have been carefully furnished with a pair of fantastic two-way speakers. It's not a powerhouse, but music lovers will appreciate its capabilities. It's also not a product you want to hide. A perfect example of form follows function. The oversized heatsinks define the A1's appearance, but they are essential to its function. Truly unique, both outside and inside. A1 has a sweet, warm, full and exciting sound. No sharpness. No graininess. Just pure music. It doesn't get muddy, and despite its lower power output, it drives difficult speakers with ease. It stays clean right up to its power limit. To hear what the A1 can do is to hear what Hi-Fi should be able to do: It creates music, pure and simple.

Improvements to the original A1

• Updated transformer for more efficient "dual mono split rail" windings
• High quality and updated ALPS RK series potentiometer as volume control
• Added IR remote for volume control
• Gain stage before 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 of the polypropylene (PP) type
• Care and attention has been paid not to change any component specifications from the original, but to update them to modern equivalents with longevity
• Layout faithfully follows the original within circuit sections of the circuit board
• Circuit sections are better organized, especially the separate power supplies and power amplifiers
• Phono stage and preamp have been improved to reduce noise and hum