UESUGI U-BROS-28

Used. In good condition. Shows signs of wear on the top panel, as visible in the photos. Original packaging not included.

110 V unit. Supplied with a 220 V step-down transformer.

The Uesugi U-BROS-28 is a tube preamplifier designed to preserve the natural character of the audio signal, delivering a fresh, refined, and detailed sound free from harshness or listening fatigue. Every aspect of its design is focused on achieving outstanding transparency, allowing the music to retain its original character without unwanted coloration while maintaining an excellent balance of detail, smoothness, and musicality.

The balanced input stage employs a specially developed transformer with an exceptionally wide and linear frequency response extending to approximately 130 kHz, ensuring full compatibility with high-resolution audio sources. The amplification stage uses carefully selected ECC83/12AX7 vacuum tubes configured in a shunt-regulated push-pull circuit, a design that enhances electrical performance while providing stable and accurate signal amplification. A negative feedback circuit of approximately 20 dB, applied from the output to the input stage, further improves linearity and reduces distortion while preserving the natural character of the music.

The preamplifier is designed to achieve optimum performance when paired with solid-state power amplifiers featuring an input impedance of 10 kΩ or higher, making it compatible with the vast majority of transistor power amplifiers. Particular attention has also been devoted to the power supply section. Both the high-voltage circuit and the heater supply incorporate effective ripple filters that significantly reduce residual noise and hum, while the high-voltage stage benefits from a total capacitance of 330 μF to ensure a stable power supply under demanding operating conditions.

The recording monitor circuit includes a dedicated defeat position, allowing the monitoring path to be bypassed during normal listening for the shortest possible signal path, while enabling it only during recording or tape playback.

The U-BROS-28 also stands out for its exceptional build quality. Its ECC83/12AX7 vacuum tubes are manufactured by the Matsushita Electric Electron Tube Division to specifications developed by Uesugi Research Laboratories and are individually selected before installation. The balanced input and power transformers are the result of a joint development between Uesugi Research Laboratories and Tamura Manufacturing, while all internal wiring is completed entirely by hand by experienced technicians using a robust lug terminal board mounted on a reinforced 1.6 mm plated metal chassis to minimize mechanical vibration. Both the signal path and the power supply incorporate dedicated filtering systems to eliminate unwanted noise, harshness, and coloration, resulting in an exceptionally clean, natural, and engaging sound reproduction.

Technical specifications:

• Product type: Preamplifier
• Unbalanced inputs: 4 line inputs + 1 playback input; sensitivity 185 mV; input impedance 125 kΩ
• Balanced inputs: 2; sensitivity 200 mV; input impedance 600 Ω
• Rated output voltage: 1 V
• Maximum output voltage: 20 V
• Total gain: 14 dB
• Total harmonic distortion (THD): ≤ 0.01%
• Frequency response: 10 Hz – 100 kHz
• Power consumption: approximately 17 W
• Dimensions (W × H × D): 43.5 × 14.6 × 36 cm
• Weight: approximately 14 kg