Luxman L-505uXII Integrated Amplifier

ODNF* Version 4.0 - Innovative amplification feedback circuit

An integral part of the design of the L-505uXII is LUXMAN's original ODNF amplification feedback circuit featuring a high-speed primary slew rate, an ultra-wide bandwidth and a low level of distortion that is achieved by feeding back only the distorted components of the audio from the amplifier's output circuit. The L-505uXII is equipped with the latest Version 4.0 ODNF circuit, resulting in a dramatically enhanced accuracy in distortion detection due to the paralleled first stage and Darlington equipped second stage amplification circuit, as well as a paralleled first stage error detection circuit. With it's lower impedance and higher S/N ratio, the L-505uXII realizes accurate reproduction of even the gentlest audio signals and achieves a full range of dynamic musical expression. The output stage, with it's parallel push-pull structure, has secured sufficient power at 100W+100W(8Ω) and 150W+150W(4Ω).

Highly accurate LECUA computerized attenuator

LECUA (Luxman Electronically Controlled Ultimate Attenuator) is at the heart of the pre-amplifier section and the sound volume adjustment function of the L-505uXII. The L-505uXII design also uses a solid state(IC) type circuit to achieve a significant reduction in size. LECUA provides an ideal level control mechanism that allows smooth and fine volume adjustment over 88 steps, thereby minimizing any deterioration of the audio signal. In addition, left and right balance adjustment is integrated into the attenuator's control functions. The multifunctional ability of LECUA ensures accuracy over the full range of the volume control, whilst suppressing any deterioration of sound quality. The volume may also be adjusted with the remote control, but when adjusting the volume manually, the tactile design and gradual motion of the control itself enables intuitive adjustment of the attenuation level.

Discrete buffer circuit

The L-505uXII features a new discrete buffer circuit in the output stage of the pre-amplifier circuit that is equivalent to the type used in our high-end C-900u separate amplifier. The pre-amp output stage is able to drive the signal with enhanced current supply capacity. The clarity of the audio signal is protected, whilst at the same time, the driving force fed through to the power amplifier stage is significantly increased. The power and reproduction capability of the L-505uXII achieves overwhelming scale sensitivity and a sharpness on start-up that cannot be achieved by conventional pre-amplifiers.

High stability power supply

The power supply of the L-505uXII consists of an EI core type power transformer, highly regulated, with four large capacity 10,000μF blocking capacitors creating a highly stable power supply. This ensures an instantaneous, constant and stable current supply.

Low impedance transmission

Large-capacity, low resistance speaker relays are connected in parallel to enable lossless transmission for the powerful driving force that is generated by the large-scale output circuit. In addition, the damping factor has been improved from 180 to 210 by lowering the impedance of the wiring pattern.