WestminsterLab Quest preamp and Rei mono power amps
Rei mono power amplifiers Description
The development of the Rei amplifier began when WestminsterLab realized the overwhelming love and admiration people had for the company’s first amplifier, UNUM. Witnessing the joy and excitement the UNUM brought to enthusiasts, the company embarked on creating a new iteration that would be more accessible in terms of affordability while preserving the essence and uncompromising performance that made UNUM exceptional. In short, the goal was to bring the cutting-edge technology and sonic experience of UNUM to a broader audience.
The UNUM was a test bed for all new ideas 10 years ago, such as point-to-point soldering, power supply design, bias control, material testing (PEEK, Teflon, etc.), heatsink design, and more. A lot has changed since then. The biasing system has gone from AB to A, and the chassis design, mechanical vibration control, power supply rails, and internal divisions have changed. Overall, the architecture is still similar, and there are many cues that the Rei has been developed from the UNUM, but the Rei is a more refined model in terms of tuning and voicing.
Not Typical Class A
The Rei amplifier, inspired by the legendary UNUM, operates in Class A with an output of up to 400 Watts. It features the company’s proprietary iBias and CCS systems, allowing for a faster warm-up time than typical Class A amplifiers. iBias technology (which, I believe, is similar to Krell’s Sustained Plateau Bias) adjusts the bias based on the amplifier’s current and load, delivering the advantages of Class A amplification while minimizing heat generation and power consumption.
Transistors matching
WestminsterLab takes a unique approach to transistor matching in amplifier design. Their transistors are carefully matched within a 1% tolerance across multiple working points on the curve. These matched transistors are stress-tested for hours under heavy loads to ensure reliability and performance. This rigorous process allows the Rei amplifier to deliver an impressive 400 watts of Class A power in a compact design.
Mechanical Construction
Stability and rigidity are crucial for a high-quality amplifier. A stable chassis allows signals and power to flow smoothly, minimizing disturbances. The Rei amplifier’s mechanical structure differs from that of UNUM. Instead of a single unibody, it features two CNC-machined aerospace-grade 6063 aluminum components. This design isolates mechanical vibrations between the power supply and the amplifier electronics, reducing the transmission of vibrations that can affect sound quality. Moreover, the external panels of the amplifier are designed to absorb micro-vibrations from the speakers while keeping resonances away from the audio spectrum. They are anchored to the power supply chassis, ensuring separation from sensitive audio components.
Asymmetric Heatsink Design
The heatsink is essential for the chassis where the “amplifier” electronics are mounted. Designing it poses engineering challenges, as it must provide mechanical stiffness while allowing for efficient heat dissipation. However, balancing these needs can lead to unwanted sound absorption. To resolve this, the Rei amplifier uses a unique asymmetric fin design for its heatsink, reducing resonance effects and minimizing sound quality impact. The heatsink’s aperture is also managed by surrounding body panels to limit exposure to audio vibrations, further reducing interference. These design features enable the Rei amplifier to effectively manage heat while preserving sound quality, ensuring stable operation with minimal audio signal interference.
Power
The design of the power supply is a crucial yet often overlooked aspect of amplifier design. A quality power supply provides low-noise voltage and current while maintaining these characteristics under demanding loads. Its ability to quickly respond to sudden load changes is vital for achieving the Rei amplifier’s exceptional clarity and precision.
Ultra-thick PCB
The printed circuit board (PCB) is a crucial component in amplifiers, connecting various elements within the system. If neglected, it can become the weakest link. After years of testing and collaboration with its supplier, WestminsterLab has developed an ideal PCB design with an ultra-thick, ultra-pure copper layer. According to the manufacturer, this advanced PCB enhances signal purity, speed, and transparency and rivals traditional point-to-point soldering.
Next: Review Context and Listening to the Rei power amplifiers
