Усилители мощности стерео — Rotel RB-1552 MkII

Rotel's RB-1552 MkII is a stereo Class AB power stage in a 3U chassis and offered in black or silver. It carries the Rotel MkII suffix used for revised versions of its separates and accepts both balanced XLR and unbalanced RCA signals, so it can sit behind preamplifiers, processors or source components with a volume control.

Key specs that matter

Rated output is 130 W per channel into 8 ohms with both channels driven across 20 Hz to 20 kHz. Both THD and IM distortion stay under 0.03%. The damping factor into 8 ohms is 500. Frequency response is 4 Hz to 100 kHz within plus 0.5 dB and minus 3 dB, and signal to noise reaches 120 dB IHF A weighted. The unbalanced input has an impedance of 12 kOhm and a sensitivity of 1.5 V, while the balanced input presents 50 kOhm with a sensitivity of 2.5 V. Power consumption is 400 W. The case measures 431 x 144 x 340 mm, and the unit weighs about 12.2 kg, or 14.3 kg packed.

Engineering and use context

A very large toroidal transformer feeds the output stage, chosen by Rotel for low electromagnetic interference and stable supply. Slit foil capacitors are used in the power supply because they can charge and discharge very quickly, which keeps the rails steady when the signal demands sudden bursts of current. Left and right channels each have independent rectification and decoupling, so demand from one channel is kept away from the supply of its neighbour. The 3U front panel lets the unit sit in a standard equipment rack as well as on a shelf. Because the high input impedance on the balanced side is several times that of the RCA side, long runs from a preamplifier with balanced outputs are easy to drive.

Pairing

Any preamplifier or processor with a fixed or variable line output can drive it, and the balanced input suits a partner with XLR outputs. The high damping factor and the stated output make it a match for passive speakers of moderate efficiency in a space of about 20 m2.

Alternatives

The Rotel RB-1582 MkII is the bigger two-channel Rotel model, delivering 200 W per channel.