Power amplifiers mono — Ubiqaudiolab Ubicube 200

The Ubicube 200 is the smallest of the three Ubicube mono power amplifiers made by Ubiqaudiolab, a high-end electronics company in Ljubljana, Slovenia, which belongs to the Akrapovič Group. It carries the circuit ideas of the Ubicube 700 and 400 into a lower-power design, which Ubiqaudiolab says it optimised for highly efficient loudspeakers rated from 97 dB onward. Each amplifier is built by hand, and stereo playback requires a pair.

Key specs that matter

Power output is 200 W into 8 ohm, 350 W into 4 ohm and 600 W into 2 ohm. The amplifier supplies 20 A rms of current, with 40 A available as a peak. Its filter capacitors add up to 228,000 µF and hold 182 J. The -3 dB bandwidth starts at DC and reaches 500 kHz. Gain is fixed at +27.75 dB, which multiplies the input voltage 24.4 times. THD plus noise is under 0.01% at 100 W into 8 ohm, residual noise lies more than 110 dB beneath full power, and damping is above 500 with 8 ohm speakers. The only input is a DC-coupled balanced XLR socket with 167 kohm impedance. The cube is 277 mm wide, 277 mm deep and 265 mm tall, and it weighs 28 kg.

Engineering and use context

The 200 has its own proprietary power module, laid out for the shortest possible signal paths and fed by a supply that Ubiqaudiolab calls oversized. The monoblock runs as a bridged design. A fully symmetrical J-FET input stage works in class A, and hand-matched lateral MOSFETs in the output stage are biased high in class AB, so the first 10 W or more come in pure class A. Power comes from a pure unregulated SMPS, filtered against EMI in both common and differential mode, and it charges a Mundorf electrolytic bank, while Jupiter and Duelund copper foil parts handle decoupling. The solid aluminium monocoque is anodised and given a hand-brushed nano coating, and copper plates inside move heat from the module through chimney-effect airflow. Software-controlled protection limits output current, keeps DC off the speaker terminals, removes RF interference and monitors module temperature, cutting the speakers off at once through a solid-state relay. The loudspeaker posts are silver-plated TUM copper. A standby button sits in the top plate beside a peak-hold power meter with a 73 dB range.

Pairing

Ubiqaudiolab tunes this model for horns and other high-sensitivity designs, and its development speakers include the Living Voice Vox Palladian horn system. Since the 200 accepts only XLR connections, the source or preamplifier ahead of it needs balanced outputs, and the company's own Ubiquitous 300B valve hybrid is made to drive its monoblocks.

Alternatives

For lower-sensitivity loudspeakers, Ubiqaudiolab offers the Ubicube 400 monoblock, which doubles the 8 ohm rating to 400 W in a larger and heavier cube.