New Concept Class AD Amplifier
The amplifier has developed from Class A to AB to Class D. Class AB was developed to improve the high heat generation and low efficiency of A.
Class D has higher efficiency and higher output than AB, and also significantly improved S/N and THD characteristics compared to A and AB. However, the sound quality has been evaluated as inferior to A/AB due to the limitations of the digital circuit. The GaN class AD amplifier developed by HiFi ROSE has dramatically improved the problems of the existing Class D by applying innovative new materials.
Class AD Amplifier
Class D amplifiers have a topology that theoretically provides a perfect linear output at 0% distortion and 100% power efficiency. In order to achieve this, the switching action requires high speed and accuracy. However, previous products were weak compared to Class A/AB in the linearity aspect due to the limitations of silicon FET, which couldn’t produce a smooth and natural sound. In the RA180, a new material, GaN FET, was used instead o Silicon FET to solve this problem. The dead time was dramatically
improved to 1/10 or less, and a nearly perfect linear output was realized with a switching speed close to zero. This linearity goes beyond the Class D limits and produces a smooth and natural sound like an analog amplifier.
The RA180 consists of two modules: one AMP module specialized for stable mid-bass and balance, and another specialized for smooth high-pitched and super tweeter areas. Each AMP module supports 200 W (8Ω) and can output up to 400 W per channel. When two independent modules are connected to a speaker’s high and low frequencies separately, the driving force can be greatly improved
without being affected by a counter-electromotive force. BTL mode combines two independent modules for rich, balanced sound.
Balanced Power Supply
The power supply that has been exclusively developed for the RA180 applies 4th generation SiC FET technology to provide high output with less heat. In addition, by using a self-developed PFC (power factor circuit), it is designed not to be affected by sudden load fluctuations, The power supply device was developed to support a powerful damping factor of at least 200, and the high output of 1000 W is designed to produce powerful bass and treble.
PHONO Amplifier with Variable EQ
The purpose of the PHONO amplifier provided by the RA180 is for the recording producer to accurately reproduce the original intention. It also reproduces the original sound as it is, which is the principle of HiFi ROSE. It is designed to respond to a variety of vinyl records with low-mid bass TURNOVER and high-frequency ROLL OFF adjustment functions. Amplifies the very weak signal picked up by the cartridge and keep it as close as possible to the original sound. MOVING MAGNET and MOVING COIL STAGES are provided with a simple switch selection and EQ values corresponding to curves from various record manufacturers are provided using parts with a 0.1% tolerance.