Overviews
The A-75 is the successor model to the classic A-70. It incorporates Accuphase's new technologies and features improvements to certain circuits, along with corresponding upgrades to components. This high-end stereo power amplifier employs Toshiba 2SA1941/2SC5198 triodes for pure Class A amplification output, with rated outputs of 480 W×2 (1Ω), 240W×2 (2Ω), 120W×2 (4Ω), and 60W×2 (8Ω). The dual-channel design utilizes 10 sets of balanced "Power Mosfet" amplification modules. Full-balanced amplification technology offers advantages over conventional amplification techniques, including superior symmetry, lower distortion, higher stability, and stronger driving capability. The A75 continues many of its predecessor's excellent design features while introducing entirely new upgrades and improvements in several key technologies. These include the incorporation of an upgraded version of the MCS circuit, known as MCS+, an initial-stage buffer amplifier circuit, an improved multi-stage parallel circuit design, and a current feedback design that ensures linear response across all levels. The amplifier circuits are connected in parallel to reduce noise, and DC-stabilized power supplies are integrated into the driver stage and MCS+ circuit to enhance the signal-to-noise ratio (S/N) and improve sound purity. To ensure a sufficient and stable power supply, the power section employs an 800VA high-efficiency large transformer paired with two 67,000µF "large reservoir" filter capacitors, providing ample and stable power. The use of a Teflon substrate with low dielectric constant and low loss rate, along with gold plating on key components such as the input terminals, enhances sound purity. Extra-large speaker output terminals facilitate the connection of high-end speaker cables. The front panel features a fully digital display of the amplifier's operating mode, with DSP digital circuitry calculating and displaying output power and operating status.
As a masterpiece during the heyday of KANGCEN (Golden Voice), the A75 has received widespread recognition and praise since its inception, representing one of KANGCEN's most iconic works. The original unit, fine-tuned with numerous high-fidelity sound elements such as pure class-A amplification and field-effect transistors, shattered audiophiles' prejudices against the "Japanese sound." It boasts a mellow timbre, exquisite and precise details in the mid to high frequencies, accurate imaging, and a deep, powerful low end, with seamless and natural transitions. Its robust driving power is sufficient to handle any speaker reputed to be difficult to drive, and even ordinary speakers can deliver a floor-standing speaker-like experience. Through this device, I've come to understand why so many audiophiles insist on amplifiers with high driving power.
After completing the development of the 1:1 direct-cut machine, we also realized that the direct-cut version might not satisfy the majority of users due to cost concerns. After careful analysis, we found that general Hi-Fi speakers rarely utilize impedances below 4 ohms, and using ten pairs of output transistors per channel seemed somewhat wasteful. Through multiple tests, we found that employing four pairs of output transistors per channel already provided excellent drive capability and low-frequency control. Moreover, there was virtually no audible difference when connecting the 1:1 direct-cut machine to 4-ohm or 8-ohm loads. By retaining the original circuit structure of the machine and simply reducing the number of output transistors, we could significantly lower various costs. The power transformer utilizes an 800W toroidal transformer, and the circuit operates at the same voltage as the original machine. Each channel employs four pairs of genuine Toshiba power transistors (2SA1941/2SC5198). Currently, there are two 67,000µF filter capacitors. The bottom houses a power soft-start and signal input board. The overall structure and functionality of the machine remain consistent with those of the direct-cut machine.
