Luxman L-550AxII, Pure Class A, Integrated Amplifier

L550AX_front_smallLuxman produced the world’s first Class A integrated amplifier in 1981 – L-550.

Luxman introduced the L-550Ax and L-590Ax in 2005, since then we have celebrated our 80th anniversary with commemorative components that have reaffirmed Luxman’s status at the pinnacle of high-end audio. In these latest integrated models, the gorgeous texture and three-dimensional performance of our original Class A amplifiers has been retained and further refined. For example, the amplifiers feature a new electronic selector switch, adopted from the input section of the C-1000f control amplifier; the internal circuitry has been revised to include customized OFC wiring and a high-speed Schottky barrier diode has been selected for the power source section; improvements that have notably enhanced the sound quality for greater musical enjoyment.

Chassis bases have superb vibration absorption in order to suppress noise levels. The power transformer, electrolytic capacitors and amplifier output stage (see amp block below) are laid out so as not to interfere with each other. To reduce interference further, the block construction isolates each section using shielding panels, and extensive internal filtering to reject magnetic flux interference.

Luxman holds many patents for audio engineering, amongst them is the application of Global Negative Feedback to the output stage, which while widely used throughout the audio industry, they no longer use themselves.

Luxman nowadays use a distortion reduction circuit called Only Distortion Negative Feedback (ODNF). This system works by isolating noise & distortion at the output from the music signal and sparingly applying negative feedback to suppress them. Conventional negative feedback systems can have an adverse effect on the music, introducing phase distortion. “The circuit features such an ultra-wide range, ultra- high slew rate and ultra low distortion that it does not use phase compensation for the music signal amplifying circuits.” This new technology also ensures that need for a DC servo circuit is alleviated, again improving sound quality.


Both the L-590AxII and L-550AxII, feature the new high quality electronic selector switch, which is the heart of the C-1000f pre-amp (one of Luxman’s 80th anniversary commemoration models). The sound quality deterioration using the new electronic input switch is now minimal, while channel separation and crosstalk efficiency were raised substantially in comparison with the previous L-550A / L-590A. In addition the illuminated position indicator around the input selector knob, makes it much easier to view the selected position even from afar.