Luxman L-550X (1983–1985)
The L-550X is the upgraded version of Luxman's L-550, the world's first pure Class A integrated amplifier when it launched in 1981. It went on sale in Japan in December 1983 at ¥269,000. That was ¥50,000 more than the original, which, as The Vintage Knob dryly notes, may be why it didn't sell especially well. The L-560 replaced it.
The big changes were a larger Bando toroidal transformer and a partly copper-plated chassis, both added to eliminate electro-magnetostriction. The circuit itself was unchanged from the L-550. Both models use the single-stage amplifier topology Luxman developed for this series, with the output stage made independent and the input grounded to eliminate power supply noise and slew rate degradation. A head amplifier is built in for MC cartridges. It uses a low-noise transistor at the input and a high-speed type at the output.
The front panel is busy by modern standards. It carries a line phase sensor, subsonic (15 Hz) and high-cut (9 kHz) filters, a pre-heating switch with warm-up indicator, a phono straight switch, a signal off switch, and a linear equalizer for adjusting rising or falling high frequencies on analog discs. There is also a nine-position turnover selector for both bass and treble. Pre/main separation is done with jumpers. There's a switched AC outlet (300W max) plus one unswitched (200W).
The numbers are strong for the era: 50W + 50W into 8Ω in pure Class A, THD of 0.008% at −3dB, and S/N of 105dB on line inputs. It weighs 20kg and measures 453 × 174 × 470mm. The L-550X arrived just after Luxman was sold to Alpine. Early units still carry the Osaka address, while later ones simply say "Japan". The T-tag is Alpine on all of them.
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