Aurorasound HFSA-01 integrated amplifier
The Aurorasound HFSA-01 is a hybrid design by Shinobu Karaki incorporates an Ultra Linear output stage featuring the tried and trusted EL84 pentodes but also utterly contemporary solid state circuitry affording a high quality phono equaliser and headphone output.
HFSA-01 is a hybrid integrated amplifier utilising the strengths of both valves and semi-conductors. The output tubes are EL84 pentodes operating in push/pull to deliver 14W/channel with very low distortion. The amplifier is equipped with defeatable tone controls and a phono stage for MM cartridges along three sets of inputs for line level sources.
The amplifier can be partnered with speakers having a load impedance of 4-8 Ohms and also offers a headphone output. The circuit elements are fairly orthodox although it is unusual to see EL84s being driven by Texas Instruments’ OPA604A high precision audio op-amps. Aurorasound has developed a perfect phase inverter circuit using these devices to optimise the push/pull operation of the output stage.
The tone controls employ CR networks for easy adjustment of bass and treble which can help get the best from a variety of speaker/room combinations. The phono equaliser uses Linear Technology devices to deliver excellent S/N characteristics and an extremely accurate correction of the RIAA curve. Separate power supplies feed the valve and semi-conductor stages eliminating any interference between them regardless of level. Rectifiers are based on the super low noise Rohm silicon carbide diodes. All transformers are custom designed by Aurorasound and manufactured in Japan.
The Aurorasound HFSA-01 is distributed in the UK by Puresound and the retail price is £3,699