This unit is a monaural power amplifier that uses the 50 — a tube developed in the 1930s — single-ended in the output stage. The configuration has a 6SN7 in the first stage and a VT-62 in the driver stage (VT-25A, 10Y, and UX-210 are also usable; the audition unit was fitted with the VT-62), which drives the 50 in the output stage via an interstage transformer.

The 50 tube operates in Class A2, and the output is 10 W — modest for the size of the unit. With its output transformer, interstage transformer, power transformer, and choke coil, the top panel has the lavish, fully-decked-out look of a dressed warship. The layout is quite elaborate, with the parts arranged in mirror image. The chassis is thick wood with extremely high rigidity. The meter mounted on the front panel displays the plate voltage.

Wide-range and refreshing; an ethereal sound of high refinement

The sound issues forth smoothly, carrying a refreshing wide-range quality. There is no sense of noise whatsoever. Musically there is no unnatural intervention — a curious sort of time flows in which the performance alone purely exists. There is not the slightest sense of band limitation from the interstage transformer; the honest resonance of the triode is striking. It is an ethereal sound — a sound of great refinement.

Jazz is rendered with a soft warmth. The sound of brass instruments resonates smoothly, without any harshness. Such gentle jazz is a rarity. With vocals, the sound image of the voice carries an indescribable sweetness. With classical music, the beauty of the texture of the strings stands out. I kept the volume modest. Amplifiers housing this kind of old-type tube are meant for driving classic speakers with efficiency exceeding 100 dB, but since no such speakers were available, we had no choice but to use the reference speaker in our magazine's listening room. If you own a high-efficiency speaker, this is a gem you would definitely want to try.