Усилители мощности стерео — Concert Fidelity DHS-300B

The DHS-300B is a single-ended triode stereo power amplifier from Concert Fidelity, the company Masataka Tsuda set up in 1987 and still runs as founder, president and designer from his own workshop in Nagano, Japan. It belongs to the Royal Purple Collection within the Resolution Series and sits beside the DHP-300B, which uses the same output tube in a push-pull circuit. No official retail figure is published, and pricing is given only on request.

Key specs that matter

Each channel has one 300B directly heated triode of the WEC type in the output stage, so the amplifier carries two in total. Rated power is 9 W per channel into 8 ohm. The drivers are a pair of 6SJ7, 6SJ7GT or 5693 tubes, one per side, and a single 5AR4/GZ34 handles rectification. The only inputs are single-ended RCA line inputs with an impedance of 220 kohm. Loudspeaker terminals are arranged as 0, 4 ohm and 8 ohm taps on the output transformers. The chassis is 450 mm wide, 140 mm high and 260 mm deep, and the amplifier weighs 11 kg without packing.

Engineering and use context

A single-ended design keeps one output tube per channel working on the whole waveform, which is why power stays in single figures even with the 300B. The 6SJ7 family offers the builder three interchangeable driver types, and the 5AR4 rectifier gives a tube-rectified supply for the high-voltage rail. As with other Concert Fidelity products, the DHS-300B leaves the factory without tubes, so the owner fits and chooses the valves. Transformers are specified for the market of sale, in versions for 100 V at 50 or 60 Hz, 110-120 V at 60 Hz, 220-230 V at 50 Hz and 240 V at 50 Hz, and Concert Fidelity does not cover faults that arise when the unit is run in a different country.

Pairing

With single-figure power, the amplifier is suited to high-sensitivity loudspeakers rather than to low-efficiency designs, and the choice of taps allows the output transformer to be connected according to the rated load of each speaker. The high input impedance barely loads a preamplifier, so tube line stages with a relatively high output impedance can drive it. Within the brand, the CF-080LSX4 and CLS-050 Mk2 line stages are the natural control units, and both share the width of this chassis.

Alternatives

The Concert Fidelity DHP-300B pairs two 300B tubes in push-pull with a 6SN7 driver and a custom interstage transformer, giving 20 W per channel in an 18 kg chassis.