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

A non-feedback single amplifier that uses the 300B, which occupies a position as a reference tube for modern tube amplifiers, as the output tube
The basic circuit uses a CR-coupled self-bias method using a pentode for the voltage amplifier. The amplification part does not use negative feedback, but uses a non-feedback method to take advantage of the good basic characteristics and obtain a natural sound field.
All transformers are equipped with a newly designed cut-core transformer to achieve better sound than the toroidal core type

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

The output tube can be selected freely, and the standard output tube is sold separately, and Emission Lab can be selected.

Most of the 300Bs from each company are designed to be replaced as they are, and there is no need for any adjustments. There is no need to adjust the hum balance, and you can get the best sound without adjustment.
Dual-wave DC ignition circuit with Schottky diodes to maximize the capabilities of the 300B
The rectifier uses a high-performance Schottky diode from IR of the United States, which can handle large currents. In addition, the smoothing capacitor with a small capacitance provides a sound with an excellent sense of speed. In addition, freshness is improved by simplifying the circuit.
The high-performance German high-performance tube C3m is used for the first stage tube, and the driver stage is composed of low noise and high sound quality.
C3M tubes are characterized by excellent electrical characteristics and very beautiful sound quality. The metal case as a loctal tube has been removed, and the glass tube is used as it is. As a result, the sound quality is more natural.
The chassis is made of wood-based materials, and in combination with the aluminum alloy transformer cover, a novel and beautiful design is realized.

It is a material with excellent strength and electricity made by laminating thin veneers of cherry wood and impregnating them with phenolic resin. The trans cover is beautifully finished with cherry wood side plates and a 2mm thick champagne gold aluminum alloy with durable anodized aluminum plating.
Fully adopted in-house Teflon sockets, which are highly regarded around the world for their high performance and reliability
The socket has a slit to hold the foot of the vacuum tube accurately. Therefore, the feet of the vacuum tube are firmly held when the vacuum tube is inserted into the socket, there is no rattling, and it has the effect of preventing the effect of external vibration on the vacuum tube.
The resistors are made by DALE, which has a good sound, and the condenser is a polypyrene film capacitor with low distortion in the main part
We use non-inductive metal-clad resistors for large resistors, high-precision wirewound resistors for medium-capacitance resistors, and metal-coated resistors and large surface-mount resistors for small-capacitance resistors. The polypropylene condenser is filled and bonded to an ebony or bakelite case with a high-strength epoxy resin adhesive to increase the strength of the condenser and further improve the sound quality.

Our original pin jack made of chrome copper is used for the input terminal, and pure copper speaker terminal is used for the speaker terminal.

The output terminals are machined pure copper and large Teflon-insulated terminals. A very thick speaker cable with a thickness of 8 mm can also be connected to this. The speaker terminal is only an 8Ω output terminal, but there is nothing wrong with using 4Ω or 16Ω speakers. However, in either case, the maximum power is reduced. If the maximum output is 8W, the output will be about 4-6W.
The legs are made of beautiful and very hard African ebony round bars
The legs are fixed directly to the complite chassis for strength and resonance, and the overall weight is precisely supported.
High-quality wire rod for power cable and hospital-grade gold-plated terminals for plugs
As the quality of tube amplifiers improves, changes in sound quality due to power cables become more sensitive. Please enjoy the change in sound due to the power cable.

Very vivid tones. Excellent projection from the room to the listening seat.
This amp is pretty close to the A-08S's aural aesthetic. In many ways, the aroma of the EML Solid Plate 45 is carried over to the 300B. The tendency is to become darker, more leisurely, and more luscious. In short, many amplifiers that are considered to sound typical of a 300B are very different from the actual sound of a 300B. The A-09S is not just a four-fold version of the A-08S 45 that sounds the same. The speakers feel surprisingly close, but they're meaty and don't get that bright. For those who find the 45 a bit lacking in sex appeal and energetic but too skinny, the 300B sibling offers a touch of color and fresh texture. It has a very three-dimensional sound field, sharp clarity, a high degree of directness that does not stick to 45 notes, and a very sophisticated tone (these far exceed 45 sounds). The drive and gain of the A-09S were also surprisingly strong, as evidenced by the wide red deck connected to the 91dB DeVore Fidelity Nines. At 2:30 a.m., at the volume of the preamp with a gain of 12 dB, the speakers were much more lively than many high-power amplifiers.
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The reproduced sound is a rich pattern filled with energy within a moderate bandwidth, and the timbre and sound quality are reflected in the wooden housing.
There is an undercurrent of warmth of vacuum tubes, but the tendency of the sound centered on clarity is impressive. The plucked string instrument has a sharp expression,
The good rise of the keyboard instrument is also impressive, giving you an exhilarating feeling. The song has a clear sense of occurrence while you can feel the warmth of the flesh voice in the background.