Усилители мощности стерео — Bryston 3B Cubed

The Bryston 3B Cubed, written 3B³ by the maker, belongs to Bryston's Cubed Series of stereo power amplifiers, built and hand assembled in Canada. It is a dual-mono design in which each of the two channels has its own fully independent power supply, including a separate transformer. It sits below the 4B Cubed in the range and uses the patented Salomie input circuit that Bryston fits to every Cubed Series amplifier.

Key specs that matter

Each channel delivers 200 W into 8 ohm and up to 300 W into 4 ohm. Frequency response extends from below 1 Hz to 100 kHz at the minus 3 dB points. THD plus noise stays below 0.005% from 20 Hz to 20 kHz at rated power into 8 ohm. Noise is specified at better than minus 111 dB through the XLR input and minus 106 dB through RCA. Input impedance is 7.5 kohm unbalanced, and on the balanced input 30 kohm on the positive leg and 6 kohm on the negative leg. Gain can be switched between 23 dB and 29 dB. The amplifier is 206 mm high and 273 mm deep, or 324 mm with front handles, its width depends on the faceplate, and it weighs about 16 kg.

Engineering and use context

The Cubed Series input circuit, developed with Dr. Salomie, uses twelve active devices, provides the first 6 dB of gain and traps distortion components in the main signal path, while improving rejection of common mode, EMI and RFI noise. For the output section Bryston chose a Quad-Complementary layout, which Bryston says removes crossover distortion through better transistor matching and cuts output stage capacitance by a factor of four. Cooling is entirely by convection through large passive aluminium heat sinks, so the amplifier runs without fans. The enclosure and dress panel are machined and anodized aluminium. A microprocessor-controlled SoftStart sequence brings the amplifier up gradually so that switch-on does not trip household circuit breakers, and standby consumption is under 500 mW. DC trigger ports let another component switch the amplifier on and off. A rear switch selects XLR or RCA input, the insulated gold-plated speaker posts are compatible with spade lugs, bananas and stripped cable, and the main circuit breaker can be reset if it trips. Bryston covers the amplifier with a 10-year warranty.

Pairing

The switchable gain helps match the 3B Cubed to preamplifiers with different output levels, with the lower setting suited to sources with high output and the higher setting to those with less. Trigger control lets it follow a Bryston preamplifier such as the BP-19 in an automated system.

Alternatives

The Bryston 4B Cubed is the stronger two-channel amplifier of the Cubed range, with more power per channel.