Yamamoto Sound Craft HA-03 Vacuum tube headphones/speaker amplifiers

HA-03 is a unique amplifier designed to provide the best sound quality for both headphones and speakers. HA-03 is a simple configuration with further amplification of high-performance vacuum tube C3m. In the case of this machine, the configuration was simplified to the limit and the attraction of the vacuum tube was maximized.

Because it is simple, sound is fresh, music can be enjoyed

The amplification circuit of this machine is extremely simple. Using the five-pole tube C3m of the vintage vacuum tube made by Siemens, Germany, as a five-pole tube connection, we draw out the moderate amplification rate and the highest quality. The circuit does not use negative feedback, but adopts the simplest natural non-feedback method. Using negative return improves performance, but sound is often unnatural.

We reduce the number of passing parts to the limit and minimize sound degradation. The screen grid circuit and the plate circuit are separate power sources, and the screen grid circuit is converted into constant voltage, resulting in a large output of about 1W at the speaker load.

The maximum output is 1.4W headphones, 1W speakers for a wide range of loads

The HA-03 is 1.4W with headphone load and 1.0W output with speaker load. The output of the vacuum tube amplifier is said to be several times more powerful than that of the semiconductor amplifier, although the output of the 1W may be felt as small. Please check with the speaker that is normally used. If you are a speaker with high efficiency to some extent, you can enjoy almost satisfactory sound up to medium volume. The corresponding headphone impedance is also available for a wide range of headphones from 16Ω to 200Ω.

The chassis adopts high insulation reinforced wood, and other high sound quality members

The chassis of this machine uses high insulation and high strength phenolic resin reinforced wood, contributing to high sound quality. In addition, high-quality components are carefully selected from all over the world, such as large earl core transformers for power transformers and winding resistance made by DALE, USA, for resistors.
The bright and vivid sound tone without blurring, the shading reproduction power is attractive. Also, if you are a small book shelf speaker, you can enjoy high-quality sound with high density.

Use vacuum tube	C3m (Vintage vacuum tube made by Siemens, Germany)
Maximum output	1.4W + 1.4W (50Ω/ headphone load) 1W + 1W (8Ω/ speaker load)
Frequency Characteristics	35Hz~17.5kHz(-3dB)
Residual noise	57μV (with A-filter)
Input Impedance	50kΩ Input switching: Two series selectable
Size	156(W)330(D)165(H)mm
Weight	5.6kg

While it is salaried, you can enjoy shaded expression with headphones with a clear reproduction power of irregularities. It is not a way to make a wide range, but a bright and vivid tone with no outline. The touch of the piano has a clear thickness, and in jazz you can feel the unexpectedly handy bass. Do the same with the speaker. If you listen to the bookshelf type in small space, it should not be impossible. It is a product that can enjoy a dense texture. I tried using SENNHEISER HD-650, but I do enough sound. Because the stress is high, any headphones should be able to listen without any difficulty.