Musical Fidelity A1
MPN #A1
Featuring 25W Class A power, discrete symmetrical circuitry, and MM/MC phono input, this amplifier offers warm, tube-like sound with enhanced power efficiency and performance<
In Hi-Fi, the Musical Fidelity A1 has become one of the most classic designs " inside and out. First released back in 1985, it quickly made waves for being an absolute beast when it came down to driving some of the most difficult speakers of that time, even though it was actually a rather low powered integrated amplifier. But: it was all done in pure Class A with excellent and expertly laid out discrete symmetrical circuitry topology and using only highest quality components. The A1 showed people that there was more to amplifiers than just high power.
Based on its huge success, the A1 has gone through multiple reissues and new versions over the years.
Now for 2023, for the first time since its initial release we have actually kept all specifications, the appearance and circuits of the 1985 rendition for those who missed out the first time. With an updated transformer, power supplies and modern low noise components we've revitalized the formula and are proud to reintroduce the fresh original " three decades later.
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.
Power Supply
The new A1 has received an updated transformer from shared (1985 original) to more efficient "dual mono split rail" windings. The amp stages are supplied by fully independent left and right power supplies for better power handling and stereo imaging and each power amplifier now has double supply capacity resulting in reduced ripple and noise.
The transformer?s noise and heat dissipation are reduced due to better efficiency and updated components. The main supplies are filtered for better regulation and reduced switch on surge.
Features
25W Pure Class A power @ 8 OhmDiscrete symmetrical topologyPlanar Audio transistors with 25A maximum outputDynamic class A, slides (NOT switches) smoothly into Class B, allowing more current as neededTherefore drives difficult speakers with no problemsUpdated transformer to "dual mono split rail" windingsFully independent left and right power suppliesEach power amplifier now has double supply capacityTransformer noise and heat dissipation reducedFiltered main suppliesGain block before volume control totally bypassable using "direct" switchHigh quality and updated ALPS RK series potentiometerLow noise TL071 JFET preamplifier circuitryDiscrete current-mode MM/MC phono input stageLow noise current to voltage converter for further amplification and RIAA equalisationAutomatic input impedance matching (1K nominal) for MC along with increased gainOriginal (1985) A1 appearance and circuits with modern improvementsRemote control added for volumeModern updated low noise components
Specifications
Amplifier
Power: 25 Watts per channel into 8 Ohms
Voltage: 42.5 Volts peak to peak
Current: 25 Amps peak to peak
Damping Factor: 150
Gain (volume max): 32dB (Direct Mode), 42dB (Normal Mode)
Output devices: 2 per channel
Signal / noise ratio: 82dB
Channel separation: 85dB
Frequency response: + 0, "1dB, 10Hz to 40 kHz
Line level sensitivity: 300mV rms nominal, 8V rms max
Line level inputs impedance: 25k Ohms
Tape Out impedance: 220 Ohms
Pre Out impedance: 100 Ohms
Phono Preamp
Phono RIAA response: +/- 1dB
MM sensitivity: 5mV nominal
MM capacitance / impedance / gain: 100pF / 50k Ohms / 40dB
MM signal / noise ratio: 75dB
MC sensitivity: 450?V nominal
MC impedance / gain: 1k Ohm / 60dB
MC signal / noise ratio: 70dB
Inputs: 1x phono RCA MM/MC, 5x line RCA
Outputs:
1 x line level RCA fix TAPE OUT1 x line level RCA var PRE OUT1 x 4mm banana/binding posts SPEAKER OUTGeneral Information
Dimensions (WxHxD): 440 x 68.3 x 283.3 mm
Main voltages: 230V/115V Internally set or 100V optional
Max. Consumption: 130W, 0W in standby (=Power Switch OFF)
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