The AOS is a dedicated no compromise fully adjustable moving coil pre-amplifier using a circuit design based heavily on Rega’s award-winning Aura reference MC phono stage.  Housed in a custom made Rega half width case, the AOS will deliver exceptional definition and greater realism to all of your recordings, bringing your favourite vinyl to life. 

Designed to work with a wide range of moving coil cartridges it has plenty of gain for low output MC’s and excellent load adjustability making it the perfect partner for whichever Moving Coil you are using.

Features

• Dedicated moving coil phono stage
• Fully adjustable for loading
• Factory pre-set for use with all Rega MC cartridges
• Circuit design based on the Reference Aura MC
• Custom aluminium design half width case
• Automatic standby function

Pure Analogue

The AOS is a two stage “all analogue amplifier” with no digital control circuitry. The fully aluminium case screens the internal circuit from any stray RFI signals. Our designers have avoided including any unnecessary components or circuits that may degrade the signal path. The AOS incorporates many innovative design ideas including a self-adjusting servo control which compensates for any variations in ambient or operating temperature.

The AOS utilises parallel connected, low noise FETs (Field Effect Transistors) configured as a compound pair. The use of FET transistors ensures there is no bias current flowing in the cartridge coil so as not to upset the delicate magnetic geometry of the cartridge. The MC input has the provision for selecting resistive input loading of 70 Ω to 400 Ω and capacitive loading of 1000 pF to 4300 pF. The input sensitivity can be changed by 6 dB via the back panel. An automatic standby feature has also been added which puts the unit to sleep after a period of no signal. This can be deactivated via dip switches located on the rear panel.

First Stage

The first stage is a symmetrical, complementary class A amplifier, using Linear Systems ultra-low noise FET (Field Effect Transistor) transistors. The use of FET transistors ensures there is no bias current flowing in the cartridge coil so as not to upset the delicate magnetic geometry of the cartridge. The input circuit configuration also alleviates the use of any coupling components between the cartridge output and the input stage FET transistors, which would degrade the sound. The complementary ultra-low noise FET transistors are carefully graded and matched for optimum performance.

This stage drives the passive high-frequency part of the RIAA equalisation stage. The complementary ultra-low noise FET transistors are carefully graded and matched for optimum performance. This stage drives the passive high-frequency part of the RIAA equalisation stage.

Second Stage

The second stage is a symmetrical, class A, differential amplifier with a common base driver stage; this is also used as the active amplifier in the low-frequency part of the RIAA equalisation stage.

Specifications

• Input Load: 70, 100, 150, & 400Ω
• Capacitive Load: 1000, 4300pF
• RIAA Accuracy (100kΩ output load): Better than ±0.2dB 65Hz to 70kHz
• Frequency Response: 17.5 Hz (-3 dB) to 100 kHz (-0.2 dB)
• THD: 0.03%
• Input Sensitivity: 69.3 dB (Gain Setting I), 63.5 dB (Gain Setting II)
• Power consumption in Standby: 0.4W
• Power Consumption: 20W
• Dimensions (WxHxD): 220 x 80 x 330 mm
• Weight: 2.9Kg

LOAD SETTINGS FOR ADJUSTABLE MC STAGES

• Gain (0dB high gain setting): 69.3dB at 1kHz
• Gain (-6dB low gain setting): 63.5dB at 1kHz