Rega AOS MC
Phono preamplifier dedicated to moving coil cartridges, with adjustable input loading and gain, from Rega.
Description
The AOS is a phono preamplifier specialised in amplifying moving coil (MC) cartridges. It sits between the turntable and the amplifier or mixing desk to deliver a phono signal compliant with the RIAA standard, with the possibility of precisely adjusting the electrical parameters according to the cartridge used.
Its fully analogue circuit is built around two stages with no digital processing whatsoever, and relies on low-noise FET transistors mounted in parallel and configured as a matched pair. This technical choice avoids any bias current in the cartridge coil, preserving its magnetic geometry. Input impedance can be set to 70, 100, 150 or 400 Ω, and load capacitance between 1000 and 4300 pF, allowing the unit to be matched to a wide range of MC cartridges on the market. Input sensitivity is adjustable in 6 dB steps (69.3 dB at gain I, 63.5 dB at gain II) directly from the rear panel. The stated RIAA accuracy is ±0.2 dB from 65 Hz to 70 kHz, for a frequency response extending from 17.5 Hz to 100 kHz and total harmonic distortion of 0.03%.
This preamplifier is aimed at users of turntables fitted with a moving coil cartridge, whether a Rega model or another brand, who are looking for the possibility of finely adjusting the electrical loading of their cartridge rather than being limited to a fixed setting. Its half-width format also makes it an option for compact installations.
Technical specifications
| Input impedance | 70, 100, 150 and 400 Ω |
| Load capacitance | 1000 and 4300 pF |
| RIAA accuracy (100 kΩ output impedance) | ±0.2 dB from 65 Hz to 70 kHz |
| Frequency response | 17.5 Hz (-3 dB) to 100 kHz (-0.2 dB) |
| Total harmonic distortion (THD) | 0.03% |
| Input sensitivity | 69.3 dB (gain I), 63.5 dB (gain II) |
| Power consumption (lighting) | 0.4 W |
| Power consumption | 20 W |
| Dimensions (W x H x D) | 220 x 80 x 330 mm |
| Weight | 2.9 kg |
What to check before buying used
The gain potentiometer deserves testing at both ends of its travel to spot any crackling or a channel dropping out, a sign of wiper wear. The input impedance switches (70, 100, 150, 400 Ω) and the load capacitance switches, often little used, can oxidise and create poor contacts: several full sweeps allow their smooth operation to be checked. The capacitors in the RIAA stage also age over the decades and can drift, resulting in a tonal imbalance or a loss of precision in the bass.
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