Yamamoto Sound Craft"2A3" Single Stereo Amplifier – New Model A-011SS

After receiving numerous awards with the A-08SS,Yamamoto Sound Craftthe design philosophy and high-quality audio technology have been further refined to develop the A-011SS, exclusively for 2A3 vacuum tubes. The 2W output of the A-08SS was insufficient for medium-efficiency speakers, but this 4W output can drive them confidently. Even with moderately efficient speakers, the rich midrange and spatial expression unique to the 2A3 can be fully enjoyed.
2A3 tubes are widely produced worldwide, from vintage to current new models, making them relatively easy to obtain. The A-011SS is designed so that most 2A3 tubes can be replaced without troublesome adjustments. No hum adjustment is required, enabling clear playback with a sense of quiet. It is truly worthy of being called the 'reference model of 2A3.'
The transparent sound, emotionally rich midrange, and powerful performance of the 2A3 vividly reproduce music.

Precise, clear sound with Vishay thin-film resistors

Extensively uses thin-film resistors from Vishay in the United States.
Compared to general carbon or metal film resistors, the error is only 0.1%, and the temperature coefficient is 10–25 ppm/°C, which is remarkably superior.
Even with large amplitudes and transients in music signals, this suppresses fluctuations in resistance, delivering accurate sound without muddiness and a high sense of quiet (noise is about 1/10 of typical metal film resistors).

SiC Schottky Diode + Independent Power Supply Circuit

Uses an 80 rectifier tube for the output stage power supply, while the driver stage is rectified with an independent Infineon SiC Schottky diode.
A clean power supply without spike currents enhances the transparency and three-dimensionality of micro signals, making localization and depth expression even clearer.

DC Filament + Ultra-Low Impedance Rectification

Drives all heaters of 2A3/717A using full-wave DC filament power.
With ultra-low-loss Schottky diodes, power supply impedance is minimized, providing fast attack and a sense of energy.
No hum balancer is used, and hum is suppressed through circuit design, avoiding any factors that could degrade sound quality.

Hi-B Material Cut-Core Power/Output Transformers

Both the power and output transformers adopt Hi-B (High-B) type cut cores.
The output transformer uses a custom 100 µm core material wound with PTFE (fluororesin) insulating paper, achieving wide bandwidth, low loss, and high linearity.
It delivers tight low frequencies, clear high harmonic tones, and a detailed soundstage.

High S/N Design with Carefully Selected Parts

Both signal and power sections are primarily composed of polypropylene film capacitors.
The use of electrolytic (chemical) capacitors, which are disadvantageous for sound quality, is minimized as much as possible.
Resistors are carefully selected high-evaluation components such as DALE metal-clad and Vishay high-capacity SMD types.

Silver-Plated Copper Wire + Fluororesin Sockets

All internal wiring uses MIL-standard silver-plated copper wire (PTFE insulated), reducing oxidation over time and maintaining initial performance for a long period.
Sockets use PTFE insulation and gold plating, offering high contact stability and excellent sound quality.

Ebony Tube Protectors

African ebony is used around the 2A3 bases. The high-quality, sharp appearance enhances the presence of the chassis.