Headphones amplifiers — Riviera Labs AIC10Bal

The AIC10-Bal is a stereo integrated headphone amplifier from Riviera Audio Laboratories, an Italian company whose circuits are designed by Luca Chiomenti. It is the only headphone amplifier in the current Riviera range, and the company deliberately left out an internal DAC and any controls it judged unnecessary.

Key specs that matter

The amplifier delivers 10 W per channel into 8 ohms in pure Class A, with 26.5 dB of gain. Input sensitivity is 135 mV for 1 W and 440 mV for full output into 8 ohms, and input impedance is 47k ohms. For sources there is a balanced XLR input next to a pair of RCA line inputs. On the headphone side the choice is a balanced 4-pin XLR socket or a 6.3 mm jack, and switchable loudspeaker terminals are fitted too. The chassis measures 26 x 43.5 x 14.5 cm and weighs 14.4 kg.

Engineering and use context

As in every Riviera amplifier, no global feedback loop is used and every stage runs in Class A. Voltage gain comes from a single-ended triode of the ECC82/12AU7 type, with one valve serving both channels, while bipolar transistors and MOSFETs make up the power stage. These output devices can dissipate 150 W continuously. The linear supply uses an oversized transformer feeding a pi filter and distributed capacitance, meaning many smaller capacitors placed close to the power devices instead of a pair of large reservoirs, for a total of more than 65,000 uF. According to Riviera, a MOSFET regulator stabilises the supply to the valve stage, and pi filtering is applied to the power stage supply as well, which is an uncommon choice. There are no active protection circuits. Riviera relies only on supply fuses and on generously sized transformers, heatsinks and power devices. A front panel selector switches between the loudspeaker output, a high-level headphone setting for low-sensitivity headphones and a low-level setting for high-sensitivity models. Two finishes are offered, Gold, a glossy sand colour with 24 kt mirror gold knobs, and Dark Titanium, a matte grey with matte aluminium controls.

Pairing

With two headphone levels, the AIC10-Bal can drive both hard-to-drive and very sensitive headphones without excess gain. Its speaker outputs can also run medium-sensitivity loudspeakers in domestic rooms, and the XLR input takes a balanced DAC or preamplifier directly.