Интегральные усилители — Concert Fidelity CF-i300B Mk2

The CF-i300B Mk2 is a valve integrated amplifier made in Japan by Concert Fidelity to designs by Masataka Tsuda, and it sits in the Resolution Series. Its output stage relies on two 300B directly heated triodes in single-ended mode, delivering 9 W per channel. The maker describes the circuit as extremely simple with short signal paths and adds a solid-state headphone amplifier to the valve power stage. Pricing is handled through the brand's distribution partners rather than a published list.

Key specs that matter

There are four line inputs. Inputs 1 to 3 are RCA, and input 4 offers a choice of RCA or balanced XLR by a switch. The input load is 100 kohm on the single-ended sockets and 50 kohm on the balanced one. The speaker terminals are marked 0, 4 and 8 ohm, giving 4 ohm and 8 ohm taps selected by the owner to suit the loudspeaker. Headphones connect through a 6.35 mm TRS jack for single-ended cables or a four-pin XLR for balanced ones. The chassis is 450 mm wide, 140 mm high and 310 mm deep, and it weighs 20 kg.

Engineering and use context

The amplifier uses two 300B output triodes, two 6SL7GT double triodes in the driver stage and one 5AR4 or GZ34 rectifier. The amplifier is delivered without valves, so the owner sources the 300B, 6SL7GT and rectifier tubes separately. Remote volume control is listed as an option that was still under development when the specification was published. The power transformer is specified per market, in versions for 100 V, 110 to 120 V, 220 to 230 V and 240 V supplies, and warranty cover applies only in the country of delivery. Correct operation on any other supply voltage is not guaranteed by the maker. The same Resolution Series also contains separate 300B power amplifiers in single-ended and push-pull form and the CLS-050 Mk2 line stage, which shares this chassis size.

Pairing

With its low output power, high-sensitivity loudspeakers are the natural match, while the selectable output taps let the transformer secondary match the nominal load of the speaker. All four inputs work at line level, so a turntable needs an external stage such as the brand's CLA-050 MC and MM phonostage. Sources with balanced outputs can use the switchable XLR input, while the other three sockets take single-ended components.

Alternatives

Concert Fidelity lists no other integrated amplifier in its current range, making the CF-i300B Mk2 its sole integrated design.