ACCUPHASE A-48S

Stereo solid-state power amplifier in pure class A fully balanced, updated version of the A-48 model.

The Accuphase A-48S is a cutting-edge Class A power amplifier. Born from years of high-performance design and engineering, the A-48S features a 6 parallel MOS-FET push-pull transistor configuration that allows it to deliver 50W at 8 ohms, 100W at 4 ohms, 200W at 2 ohms, and 400W at 1 ohm, all while maintaining the compact size typical of conventional models. With a damping factor of 1,000 and a 6% reduction in noise level, the A-48S ensures a dynamic and expansive listening experience, bringing out the finest details from any speaker.

As the fifth generation of Accuphase's pure Class A amplifiers, the A-48S improves upon its predecessors, including the A-48 launched in 2019, with increased power, better drive capabilities, and improved sound performance with reduced noise. The A-48S offers a linear output power of 50W at 8 ohms and 200W at 2 ohms, with a 25% higher damping factor and a 6% lower noise level compared to the previous model. The pure Class A sound delivers immediate and realistic audio quality, capturing the most subtle nuances and emotional expressions of the music.

The A-48S is equipped with highly sensitive analog "needle" meters that allow monitoring of output power even at low volumes. The front panel includes a gain selector with four settings: Max, -3dB, -6dB, and -12dB, enabling easy adjustment of performance based on the type of speaker used. The gain adjustment occurs in the input section without directly affecting the signal, ensuring stable operation and reducing residual noise, especially when using high-efficiency speakers.

The amplifier's monoblock design integrates a custom-made, powerful toroidal transformer and two large 68,000μF capacitors at the center of the unit, ensuring a strong and stable power supply. Each channel is separated to improve isolation, while the overall design maximizes the amplifier's ability to drive speakers with a wide dynamic range. With a nominal output power of 50W at 8Ω, 100W at 4Ω, and 200W at 2Ω, the A-48S far exceeds the capabilities of conventional models, offering a wide and detailed soundstage.

The 6 parallel push-pull MOS-FET transistor configuration reduces output impedance, increasing drive capability and reducing the load on each transistor, allowing the amplifier to operate safely under all conditions. Additionally, the A-48S uses balanced circuits in the signal input section to suppress external noise, offering high gain (12.6x) and ensuring precise, low-noise amplification.

With a guaranteed damping factor of 1,000, the A-48S improves drive capabilities compared to previous models, reaching levels similar to Accuphase's flagship models, the A-300 and A-80. To improve reliability and sound quality, the A-48S uses a MOS-FET switch for speaker protection, replacing traditional mechanical relays, reducing contact resistance, and enhancing overall performance.

The amplifier also integrates "Balanced Remote Sensing" technology, which further reduces output impedance by applying negative feedback from both the speaker terminals and the ground level, improving damping factor, total harmonic distortion (THD), and intermodulation distortion (IMD). The output protection circuit can detect short circuits at the speaker terminals, while temperature sensors monitor the heat sink temperature, ensuring safe operation and preventing overheating. When the protection circuits are activated, the output to the speakers is completely interrupted, and the power meters flash to signal an abnormal condition, ensuring safety and optimal performance.

The A-48S is the ideal choice for those seeking a high-performance, pure Class A amplifier that combines cutting-edge technology, superb sound quality, and robust protection features, all within a compact and reliable design.

Technical Specifications:

• Power: 50 W per channel at 8 Ohms, 100 W at 4 Ohms, 200 W at 2 Ohms, 400 W at 1 Ohm
• Bridge Mono Configuration: 200 W at 8 Ohms, 400 W at 4 Ohms, 800 W at 2 Ohms
• Frequency Response: 0.5 Hz to 160 kHz
• Total Harmonic Distortion (THD): 0.03% from 4 to 16 Ohms (Normal/Dual Mono), 0.05% from 4 to 16 Ohms (Bridge)
• Signal-to-Noise Ratio (S/N Ratio): up to 123 dB
• Intermodulation Distortion: 0.01%
• Power stage in symmetrical Mono Block configuration with separate modular circuits for the left and right channels
• MCS+ (Multiple Circuit Summing-up) parallel voltage amplification technology
• Power MOS-FET transistors in parallel Push-Pull configuration (6 elements)
• Current Feedback output stage with Balanced Remote Sensing technology for ultra-low impedance
• Damping Factor greater than 1000
• Power supply stage with oversized toroidal transformer and proprietary filter capacitors (2x 68,000μF)
• Variable gain with 4 settings (Max/-3/-6/-12 dB)
• Speaker protection circuit with ultra-low resistance MOS-FET semiconductors
• Power stage protection circuit with optocoupler and temperature sensor to detect overcurrents and overheating, with instantaneous current cut-off
• Polarity selector to invert pins 2 and 3 of the balanced XLR connection
• Analog Peak Output Power Meters
• Dual oversized speaker terminals
• Dimensions: 465 x 211 x 464 mm
• Weight: 34.8 kg