Quad Artera Solus

At the heart of the Solus is an ES9018 Sabre32 Reference, the eminent 32-bit, eight-channel hybrid multi-bit Delta-Sigma DAC chipset. External sources benefit from this DAC's quality via a range of digital inputs, handling PCM data up to 32 bit/384 kHz as well as DSD64/128/256. For CD replay, a slot-loading mechanism buffers data from the disc before feeding it to the asynchronous DAC section. Four digital filter options enable users to tailor the sound from both CDs and external digital sources, to suit personal taste and the nature of the source material. The Artera Solus's preamp and power amp sections mix minimalist design with high-quality components to ensure short, direct signal paths to preserve sonic purity. Volume is digitally controlled in the analogue domain, outputting directly to the dual-mono Class AB power amp section. This delivers 2 x 75 W into eight ohms, with a maximum current delivery of 15 Amps into difficult loads. To minimise distortion, the power supplies for the left and right channels are isolated from each other as well as from the rest of the system.

The discrete power amp circuits' output stage uses a CFB (Complementary Feedback) topology in combination with conventional emitter follower circuitry. The CFB stage offers superior linearity and ensures excellent thermal stability, says Quad, as the idle current is kept independent of the temperature of the output transistors. Using an emitter follower in combination with the CFB stage is an efficient way of increasing the current ability of the amplifier without compromising the advantages of the CFB circuit. Having the emitter follower deliver additional current only when needed allows for a simpler current-limiting arrangement, which can be voltage independent. Current limiting is under microprocessor control and programmed to allow the amplifier to supply high currents into complex loads. A 300VA toroidal transformer supplies the two mono amplifiers using separate secondary windings, followed by 2 x 15000 µF reservoir capacity per channel (60000 µF in total).

Much effort has gone into the physical layout of the Artera Solus's circuitry, with independent low-noise power supplies feeding all critical stages to keep interference to a minimum. Cable connectivity options are plentiful. Five digital inputs - two coaxial, two optical and one USB Type B - cater for external digital sources (there's also a USB Type A socket for software updates) while a pair of RCA phono inputs handle analogue sources. Analogue outputs are supplied in both single-ended RCA and balanced XLR varieties, with the four-channel volume control preserving the balanced signal path from the DAC to the XLR output. A pair of high-quality speaker binding posts, optical and coaxial digital outputs, a 12V trigger output and a front-mounted jack coupled to a dedicated headphone amp circuit complete the connectivity array.

Later this year, a second version of the Artera Solus will join the Bluetooth-equipped model. This premium version will add comprehensive app-controlled Wi-Fi network streaming facilities, thus delivering greater choice to the consumer - if Bluetooth is sufficient and you don't require full network streaming, you won't have to pay for a redundant facility, but the option will be available for those who want it. Those who purchase the standard Bluetooth model can upgrade their unit to the fully loaded network streaming version should they wish to do so, once available this autumn. The new Artera Solus is available with a choice of black or silver front panels and a recommended retail price of £1,499.95. Info and photos by Quad.