Усилители мощности стерео — Kondo Audio Note Japan Ongaku

Kondo Audio Note Japan makes the Ongaku, a two-channel valve power amplifier built around 211 triodes working in single-ended mode. It was introduced in 1989 and remains in the current Audio Note catalogue, where it is the only stereo model that uses the 211 - the Kagura2 i and Gakuon II apply the same triode in monaural form, with two 211 valves in parallel per chassis. Each unit is hand-wired point to point by the company's technicians, and the chassis is made of copper.

Key specs that matter

Rated output is 27 W per channel at 1 kHz with 5 percent THD. Audio Note specifies a response from 10 Hz to 21 kHz. Four RCA input pairs are fitted, each with an impedance of 100 kohm, which lets the Ongaku accept several line sources directly. Residual noise is under 1 mV. Output comes from the 211 pair alone. The valve line-up comprises two 211 output triodes, two 6072, two 5687 and four GZ34 rectifiers. The amplifier measures 284 mm wide, 240 mm high and 550 mm deep and weighs 34 kg.

Engineering and use context

Audio Note describes the circuit as one designed to exploit the linearity and low distortion of the 211 triode. The output transformers are wound by hand with pure silver wire and have a primary impedance of 12 kohm, using a multi-layer construction. Like the transformers, the signal capacitors are made by Audio Note in-house, with electrodes of pure silver foil. Internal connections use the company's SSW cable, which consists of pure silver conductors wrapped in natural silk insulation. The copper chassis was chosen by the maker as part of the design rather than steel or aluminium, and the four GZ34 rectifiers supply the high voltage needed by the 211 output valves. With several inputs on board, the Ongaku was conceived as an amplifier that can also sit at the end of a short chain, although a separate preamplifier can still be used ahead of it.

Pairing

A line preamplifier with RCA outputs can feed one of the four input pairs, and the high input impedance suits valve line stages such as Kondo's own G-1000i, which has two RCA outputs. The modest power rating of this 211 design sets the power limit that any connected loudspeaker must suit. Sources and preamplifiers with only XLR outputs cannot be connected without adapters, since the Ongaku has no XLR socket.

Alternatives

The Kondo Melius is the other stereo power amplifier of the brand, an EL34 push-pull design rated at 32 W per channel.