Yamamoto Sound Craft A-09S 300B Single Stereo Amplifier

Single-pass amplifier with a no-feedback type using the 300B output tube, which holds the position as a reference tube for modern vacuum tube amplifiers.
The basic circuit uses a self-biasing method of CR coupling using a pentapole tube in the voltage amplifier section. The amplifier section does not use negative feedback, but uses a no-feedback method to make use of the good basic characteristics, and obtains a natural sound field.
All transformers use newly designed cut-core transformers, achieving better sound than the toroidal core type.

The toroidal core transformers used in power transformers, output transformers, and choke coils had excellent sound quality, but because they lacked stability, the company changed all transformers to newly designed cut-core types, resulting in a stable, more dynamic sound than the toroidal core transformers.

The standard output tube can be sold separately, and Emission Lab can be selected as a standard output tube.

Most of the 300Bs from each company are designed to be replaced as is, and no adjustments are required. No adjustments to the hum balance or other things are needed, and you can get the best sound without adjusting.
Double-wave rectifier DC ignition circuit using Schottky diodes to maximize the capabilities of the 300B
The rectifier uses a high-performance Schottky diode from the US company IR that supports large currents. Furthermore, the small capacity smoothing capacitor gives a sound with excellent speed. We also strive to improve freshness by simplifying the circuit.
The first stage tube uses high-performance German-made high-performance C3m tube, making it a low noise and high-quality driver stage.
C3m tubes are characterized by their excellent electrical properties and extremely beautiful sound quality. The metal case used as a Roctal tube has been removed and used as a glass tube. This gives the sound quality even more natural.
Wooden material is used for the chassis, and combined with an aluminum alloy transformer cover creates a novel and beautiful design.

This material is made of thin, solid cherry wood laminated and impregnated with phenolic resin to harden it, making it a material that is both strong and electrically excellent. The transformer cover uses a 2mm thick champagne gold aluminum alloy made from cherry blossom-based side panels and durable anodized plating, making it a beautiful finish.
Fully adopts our own Teflon sockets, which are highly regarded around the world for their high performance and reliability.
The socket has a slit to hold the vacuum tube feet accurately. Therefore, the vacuum tube's feet are held firmly when the vacuum tube is inserted into the socket, and there is no rattling, preventing the effects of external vibrations on the vacuum tube.
The resistances are made by DALE, which has good sound, and the main parts are polypyrene film capacitors with little distortion.
Large resistors use uninductive metal clad type, medium-capacity type with high-precision winding type, and small-capacity type with metal coating resistors and large surface-mount resistors. Polypropylene capacitors are filled and adhered to ebony or bakelite cases with high-strength epoxy resin adhesive, increasing the strength of the capacitor and further improving the sound quality.

Our original pin jack with chrome copper is used as the input terminal, and pure copper speaker terminal is used as the speaker terminal.

The output terminals are large Teflon-insulated terminals with pure copper machined gold plating. This also allows you to connect an extremely thick speaker cable, which is 8mm thick. The speaker terminal is only an 8Ω output terminal, but there is no problem with using 4Ω and 16Ω speakers. However, in both cases, the maximum output will be lower. If the maximum output is 8W, the output will be around 4-6W.
A beautiful, extremely hard African ebony round bar with a resonance on the legs
The legs are directly secured to the Comprite chassis to provide good strength and sound, and are accurately supported by the overall weight.
High-quality wires are used for the power cables, and hospital grade gold plated terminals are used for the plugs
As the quality of vacuum tube amplifiers improves, changes in sound quality due to power cables become more sensitive. Please enjoy the changes in sound due to the power cable.

Very vivid tone. Excellent projection power from the room to the listening sheet.
This amplifier is pretty close to the aural aesthetic of the A-08S. In many ways, the fragrance of the EML solid plate 45 is carried over to the 300B. This trend is deeper, more leisurely, and more sweet. . In short, many amplifiers that are considered typical 300B sounds are quite different from the actual 300B sounds. The A-09S is not simply made the same sound as the A-08S 45 with four times the power. The speakers feel surprisingly close, but they are thick and don't brighten. For those who find the 45 a bit lacking in sexiness and energetic but too thin, the 300B brothers give them colour and fresh texture. It has a very three-dimensional sound field, sharp clarity, and high-level directness that does not stick to the 45 sounds, and is extremely refined (these are far beyond the 45 sounds). The A-09S's drive and gain were also surprisingly strong, and was revealed when the wide red deck was connected to the 91dB DeVore Fidelity Nines. At 2:30, the volume of a preamp with a gain of 12dB, and the speakers were far more dynamic than most high-power amplifiers.
*sixmoon.com
The reproduction sound is a rich pattern filled with energy within a moderate band, and the tone and sound quality is reflected by the wooden housing.
The warmth of the vacuum tube can be felt as undercurrent, but the sound trend, which is centered around clarity, is impressive. The plucked string instrument has a sharp look,
The good standing up of the keyboard instrument is also impressive, giving you a refreshing feeling. The song is a clear feeling of the warmth of the sound behind it, yet still produces a clear feeling.