Интегральные усилители — MasterSound Evolution 845

The MastersounD Evolution 845 is a dual mono stereo integrated valve amplifier with a parallel single-ended Class A output stage built on 845 directly heated triodes and run without global negative feedback. It was designed and built by hand by MastersounD, the Italian valve amplifier maker founded by Cesare Sanavio, whose sons Luciano and Lorenzo Sanavio continued the company.

Key specs that matter

Output is 55 W per channel from four 845 triodes, two per channel, preceded by two ECC802 (ECC82) pre-drivers and two 6SN7 drivers. Its RCA sockets serve three line sources plus a direct input, and 1 V of input signal gives full output. Frequency response is 8 Hz to 40 kHz within 0 dB, and the amplifier drives loads of 4 to 8 ohms. The chassis measures 54 x 47 x 27 cm and weighs 53 kg.

Engineering and use context

MastersounD regards transformer design as central to its work, and the output transformers in the Evolution 845 were designed and wound in house. The preamplifier section uses a dual drive control system developed for this model, and the circuit board has 24 carat gold connections. Bias is semi-automatic, set once through a bias control input on the rear panel and then held by the circuit to extend output valve life. The rear panel also carries a fused mains inlet and six speaker terminals, two black and four red, giving separate 8 and 4 ohm connections for each channel. Each of the four 845 sockets is marked A to D and the valves fit in only one orientation, so they must be matched to their positions when the amplifier is unpacked. When first switched on, the front LED blinks red and turns steady once operating voltages are reached, and the maker advises about thirty minutes of warm-up. Volume is controlled from a remote handset. With four 845 valves the amplifier runs hot, so it needs a solid, level surface away from heaters, and valves should never be fitted or removed while it is switched on. The five-year warranty excludes the valves and is void if the amplifier is run without speakers connected.

Pairing

Through its direct input the Evolution 845 can be fed by a separate preamplifier, leaving the internal volume stage out of the chain. With this power reserve, it is best matched with loudspeakers of 88 dB sensitivity or more, in rooms of 20 m2 and larger. The amplifier has no RIAA input of its own, so records need an external phono preamp.

Alternatives

The MastersounD Compact 845 is the smaller integrated using a single 845 triode per channel instead of a parallel pair.