Интегральные усилители — Staccato Audio Audio BU-01

The Black Unique BU-01 is a pure Class A dual-mono integrated amplifier from Staccato Audio, a small company in Poland owned by designer Jakub Honkisz, who builds each unit by hand. Before moving into complete amplifiers, the brand made discrete operational amplifier modules sold under the OSH, or Open Sound Hybrid, name. The BU-01 was announced at EUR 14,990, and it costs USD 15,990 in North America. The casework is offered in ten colour options, and a metal remote handset is supplied.

Key specs that matter

Staccato rates the amplifier at 2 x 82 W into 8 ohm and 2 x 110 W into 4 ohm, with RMS figures of 2 x 58 W and 2 x 78 W for the same loads. THD+N is 0.05% from 20 Hz to 20 kHz at 1 W into 4 ohm, and frequency response runs from 1 Hz to 90 kHz between -0.1 dB and -3 dB. Signal-to-noise ratio is 91 dB at full output, with a noise level of -91 dBV. There are six line inputs on Furutech FT-903 RCA sockets, a single RCA pre-out and WBT 0703 Cu copper binding posts, but no phono stage and no XLR connections. The chassis measures about 450 x 180 x 414 mm and weighs about 30 kg.

Engineering and use context

The BU-01 gives every channel a separate balanced CLCLC power supply, in which chokes and capacitors alternate to filter voltage and current. Per leg and per channel the supply uses one vintage paper-in-oil capacitor, two Mundorf M-Lytic electrolytics and two vintage mil-spec air-core chokes. The mains transformer sits behind a triple electromagnetic shield, and a distributed ground network with hum-isolating resistors keeps loops out of the audio circuit. The output transistors are matched in pairs to within 1 mV. Honkisz lays out every circuit board himself. Volume is set by a remote-controlled stepped attenuator with 64 steps of 1 dB, and a microcontroller stores a separate start-up level for every input. A soft-start circuit brings the amplifier up gently at switch-on to protect its parts. Because Class A output devices conduct all the time, the amplifier runs hot, and the grilles and vent holes in the case need open space around it. The pre-out lets the BU-01 act as a line stage for another power amplifier or feed an active subwoofer.

Pairing

Loudspeakers of average or higher sensitivity with a benign impedance curve make the best use of a Class A design of this power. All sources must be line level, so vinyl playback calls for a separate phono preamplifier, and balanced sources require XLR to RCA adapters.

Alternatives

Staccato Audio has no other integrated amplifier in its range.