In the Hi-Fi audio field, amplifier technology has continued to evolve in the order of Class A, Class AB, and Class D. Class D amplifiers that utilize the latest technology are outstandingly superior in efficiency compared to Class A or AB amplifiers, and have achieved significant improvements in signal-to-noise ratio (S/N) and total harmonic distortion.
However, despite these advantages, evaluation shows a lack of sound quality compared to analog amplifiers due to the limitations of digital circuits. To overcome these limitations, HiFi ROSE independently developed Class AD amplifier technology using GaN (gallium nitride) FETs and applied this technology to the RA280. It achieved sound quality comparable to analog while maintaining the efficiency and power amplification of existing Class D amplifiers.
Class D amplifiers are known for their high efficiency, low total harmonic distortion rate, and theoretical topology of perfectly linear output. The speed and accuracy of switching operations are essential to achieve perfect Class D design theory.However, conventional products are lacking in linearity compared to Class A and AB amplifiers due to the limitations of silicon FETS (field effect transistors). It is clear that conventional products had limitations in providing smooth, natural sound quality. To improve on these problems, RA280 uses the innovative new material gallium nitride (GaN) to replace the previously used silicon FET (field effect transistor). This dramatically improves dead time to 1/10 of the previous level and implements linear output with a switching speed close to zero. This improvement in linearity is the result of pushing the limitations of Class D amplifiers, allowing smooth, natural reproduction of sound quality with the fluidity of an analog amplifier.
