Усилители для наушников — MasterSound Senso

The Senso is a valve headphone amplifier from MasterSound, the Italian company founded in 1995 near Vicenza, known for its single-ended Class A amplifiers and in-house transformers. It is MasterSound's first headphone amplifier and uses a KT120 power valve per channel in Class A single-ended mode. It also works as a preamplifier and includes an MM phono input.

Key specs that matter

Output is 2 x 3.5 W in Class A from two KT120 output valves, with two ECC802 double triodes, a long-plate low-microphonic version of the ECC82, in the preamplifier and driver stages. Inputs are three RCA pairs, one XLR and one MM phono. Outputs are one RCA pair at the rear, a 6.35 mm jack, a 4-pin XLR and two 2-pin XLR headphone outputs. Input sensitivity is 1 V. Headphone impedance settings are low, 15 to 60 ohms, medium, 60 to 200 ohms, and high, 200 to 500 ohms. Frequency response is 18 Hz to 49 kHz.

Engineering and use context

Most valve headphone amplifiers use small signal valves, but the Senso uses a KT120 beam tetrode, a power valve normally found in loudspeaker amplifiers, in a single-ended output stage. Single-ended Class A operation keeps one valve per channel conducting through the whole waveform, and the output transformer, which MasterSound winds itself, matches the valve to the headphones. The three impedance settings select transformer taps suited to the headphone's load, so both 32 ohm planars and 300 ohm dynamics receive a correct match, with the power available to drive difficult headphones. MasterSound regards the output transformer as the most important part of any valve amplifier, and all its transformers are designed and hand built in-house. The ECC802 driver valves reduce microphony, which matters in a headphone amplifier where valve noise is close to the ear. The balanced 4-pin and dual 2-pin XLR outputs suit headphones with balanced cables. The MM phono input and line output let the Senso act as the centre of a small system. The Hong Kong price was HKD 69,900. MasterSound was founded by the Sanavio family, and its first product was the 2-11 A amplifier. The Senso weighs 18 kg.

Pairing

The Senso suits both low-impedance planar headphones and high-impedance dynamic models. Its line output can feed a power amplifier.

Alternatives

MasterSound makes no other headphone amplifier, so the Senso stands alone in its catalogue as the brand's only valve design for headphone listening.