Интегральные усилители — Luxman L-505uXII

The L-505uXII is a Luxman integrated amplifier with an onboard phono preamplifier for MM and MC, described by the maker as the latest in the long L-505 series. It brings the proprietary ODNF Version 4.0 feedback circuit and the LECUA computerized volume control into a 440 mm wide chassis, with tone controls, a record output and separable preamplifier and power sections.

Key specs that matter

Rated output is 100 W per channel into 8 ohm and 150 W per channel into 4 ohm. The line input has a sensitivity of 180 mV at 47 kohm, and the balanced line input 180 mV at 55 kohm. The main input needs 1 V at 47 kohm. For phono, MM sensitivity is 2.5 mV at 47 kohm and MC sensitivity is 0.3 mV at 100 ohm. Line frequency response is 20 Hz to 100 kHz within -3 dB, while the phono section covers 20 Hz to 20 kHz within -3 dB. Total harmonic distortion is 0.009% at 1 kHz and 0.09% across 20 Hz to 20 kHz, both into 8 ohm. Signal to noise is 104 dB or more for line, 91 dB or more for MM and 75 dB or more for MC. The damping factor is 210.

Engineering and use context

ODNF stands for Only Distortion Negative Feedback, the Luxman approach that feeds back only the distortion component rather than the whole signal. Version 4.0 uses a paralleled first stage and a Darlington second stage with improved accuracy of distortion detection. Level control comes from LECUA, the Luxman Electronically Controlled Ultimate Attenuator, in 88 fine steps, and it also handles left and right balance. A discrete buffer circuit equivalent to the one in the C-900u raises current supply to the power stage. The supply uses an EI-core transformer with four 10,000 uF block capacitors, and large low-resistance speaker relays sit in the output path. Internal wiring is OFC cable with spirally wrapped shielding, laid out in a Beeline construction without angled runs. A headphone output and the RA-17A remote are included. Bass and treble controls give 8 dB of range at 100 Hz and 10 kHz respectively. The rec out provides 180 mV and the pre-out 1 V, so the amplifier can feed a recorder or an outboard power amplifier, and the main input lets an external preamplifier drive the power stage. Power draw is 270 W in operation, 85 W with no signal and 0.4 W on standby. The case measures 440 x 178 x 454 mm at 22.5 kg.

Pairing

The phono section handles moving coil pickups directly with no external step-up needed.

Alternatives

The Luxman L-507uXII is placed higher in the same range with 110 W into 8 ohm and 210 W into 4 ohm per channel.