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

A non-reduction single amplifier that uses the 300B output tube, which occupies a position as a reference tube in modern tube amplifiers.
The basic circuit uses a CR-coupled self-bias system with a pentode tube in the voltage amplification section. The amplification section does not use negative feedback, and the non-refeedback method takes advantage of the good basic characteristics to obtain a natural sound field.
Newly designed cut-core transformers are used for all transformers to achieve better sound than toroidal-core transformers.

The toroidal core transformers used in the power transformer, output transformer, and choke coil had excellent sound quality, but lacked stability.

Standard output tubes are sold separately, and Emission Lab's output tubes can be selected.

Designed so that most 300B tubes from various companies can be replaced without modification. No need to adjust the hum balance, etc., and the best sound can be obtained without any adjustment.
Double-wave rectified DC ignition circuit with Schottky diodes to maximize the 300B's performance
The rectifier uses a high-performance Schottky diode manufactured by IR of the U.S.A., which is capable of handling large currents. In addition, a small smoothing capacitor provides a sound with an excellent sense of speed. In addition, the simplification of the circuit improves the freshness of the sound.
High-performance German-made C3m tube is used for the first stage tube to provide a low-noise, high-quality sounding driver stage.
The C3m tube is characterized by its excellent electrical characteristics and beautiful sound quality. The metal case of the metal tube is removed and the glass tube is used as it is. This gives a more natural sound quality.
Wooden material is used for the chassis, and in combination with the aluminum alloy transformer cover, a novel and beautiful design is realized.

Thin veneers of cherry wood are laminated and hardened with phenolic resin impregnation, a material that is both strong and electrically superior. The transformer cover is beautifully finished with cherry wood side panels and durable anodized 2mm-thick champagne gold aluminum alloy.
All over the unit, we use our own Teflon sockets, which are highly regarded around the world for their high performance and high reliability.
The socket is designed with a slit to precisely hold the tube legs. Therefore, when the vacuum tube is inserted into the socket, the tube legs are held firmly and do not rattle, preventing external vibrations from affecting the tube.
Resistors are made by DALE for excellent sound, and polypyrene film capacitors with low distortion are used in major parts of the capacitors.
Non-inductive metal-clad type is used for large resistors, high-precision wire-wound type is used for medium-capacity types, and metal-coated resistors and large surface-mount type resistors are used for small-capacity types. Polypropylene capacitors are filled and bonded to ebony or Bakelite cases with high-strength epoxy resin adhesive to increase the strength of the capacitors and further improve sound quality.

Our original pin jacks made of chrome copper are used for input terminals, and pure copper speaker terminals are used for speaker terminals

For the output terminals, we use large terminals machined from pure copper, gold-plated, and insulated with Teflon. It is possible to connect a very thick (8mm) speaker cable to this terminal. The speaker terminals are 8Ω output terminals only, but there is no problem using 4Ω or 16Ω speakers. In both cases, however, the maximum output power will be reduced; a maximum output power of 8W will be reduced to about 4-6W.
The legs are made of beautifully resonant and very hard African ebony round rods
The legs are fixed directly to the Compright chassis for strength and resonance, and to support the overall weight properly.
High-quality wire material is used for the power cable, and hospital grade gold-plated terminals are used for the plugs.
As the quality of tube amplifiers improves, changes in sound quality caused by power cables become more apparent. We hope you will enjoy the sound changes caused by power cables.

Very vivid tone. Excellent projection from room to listening seat.
This amplifier is quite close to the aural aesthetic of the A-08S. In many respects, the 300B carries over the aromaticity of the EML Solid Plate 45. In many ways, the 300B inherits the aromaticity of the EML Solid Plate 45, but in many ways, the 300B is darker, more languid, and sweeter. In short, many amplifiers that are considered typical of the 300B sound are very different from the actual 300B sound, and the A-09S is not simply the same sound as the A-08S 45 with four times the power. The speakers feel surprisingly close, but they are thicker and not as bright. For those who find the 45s a bit lacking in color, energetic but too skinny, the 300B siblings provide color and lush texture. The sound field is extremely three-dimensional, the clarity sharp, and the tone highly refined with a high degree of directness that does not stick to the 45's sound (which is far beyond the 45's sound). The A-09S's drive and gain were also surprisingly powerful, as was evident when the wide red deck was connected to the DeVore Fidelity Nines at 91dB; at 2:30 and 12dB of gain at the preamp volume, the speakers were much more lively than many high-powered amplifiers! ...and the speakers were much more dynamic than most high output amplifiers!
*sixmoon.com
The reproduced sound is a rich pattern filled with energy within a good bandwidth, and the wooden enclosure reflects this in terms of tone and sound quality.
There is a sense of warmth from the vacuum tubes as an undercurrent, but the tendency of the sound to be centered on clarity is impressive. The stringed instruments have a crisp expression,
The keyboard instruments are impressive for their crispness and freshness. The singing is clear and clear, with the warmth of the flesh voice in the background.