Интегральные усилители — Rotel A12MKII

The Rotel A12MKII is a slim Class AB stereo integrated with an internal DAC, a computer USB input and wireless Bluetooth. An oversized toroidal transformer built by Rotel is at the core of the supply, and the source list covers a moving magnet phono stage, four RCA analogue inputs, four digital inputs, PC-USB and aptX Bluetooth. The amplifier is certified as Roon Tested, and Rotel builds it in a silver or a black version.

Key specs that matter

Continuous output is 60 W per channel into 8 ohm, maximum output reaches 120 W per channel into 4 ohm, and the FTC rating is 75 W per channel into 8 ohm. THD is below 0.018% and intermodulation distortion below 0.03%, with a damping factor of 220. Frequency response is 10 Hz to 100 kHz within 0.5 dB for line, 10 Hz to 90 kHz within 2 dB for digital and 20 Hz to 20 kHz within 0.5 dB for phono. Measured with A-weighting, noise figures reach 100 dB on line, 103 dB on digital and 90 dB on phono. Line inputs need 230 mV at 24 kilohm, the MM stage needs 3.4 mV at 47 kilohm, and digital inputs are 0 dBFS at 75 ohm.

Engineering and use context

A Texas Instruments 32-bit/384 kHz DAC handles conversion. S/PDIF inputs accept LPCM up to 24-bit/192 kHz, and PC-USB works in USB Audio Class 1 up to 24-bit/96 kHz or, after driver installation, Class 2 up to 32-bit/384 kHz. Overload limits are 4 V on line inputs and 50 mV on phono. A 1.2 V preamplifier output with 470 ohm output impedance is fitted, and tone controls give plus or minus 10 dB at 100 Hz and 10 kHz. Rotel publishes an RS232 protocol and IR codes for integration. The chassis measures 430 x 93 x 345 mm, has an 80 mm front panel and weighs 8.76 kg. The 120 V, 60 Hz US unit draws 230 W, idles under 0.5 W in standby and Rotel gives 632 BTU/h as its thermal figure at 1/8 power. Several voltage and current regulators give independent supplies to the analogue, digital and amplifier stages, the transformer feeds high efficiency storage and smoothing capacitors, and the circuits follow the Rotel Balanced Design Concept.

Pairing

A laptop running Roon can connect over USB, a streamer or TV can use a coaxial or optical input, and vinyl from an MM pickup goes to the phono stage. Dual A-B speaker terminals allow two pairs of loudspeakers, while 12 V triggers and a remote input link the amplifier to control systems. The pre-out makes room for a powered subwoofer or a separate power amplifier.

Alternatives

With a lower 50 W per channel rating, coaxial, optical and aptX HD Bluetooth inputs and no USB port, the Rotel A11MKII is the smaller integrated amplifier choice.