Integrated Amplifiers

Power meters are always fun to watch and, here, are ‘calibrated’ in dB relative to full output. In practice the red ‘0dB’ point is pretty close to Luxman’s rated 120W/8ohm but, perhaps more importantly, a 10W/8ohm output is indicated at –15dB when the amplifier is cold and –10dB when it is warm... So treat the meters as decoration rather than a precise measure of level! Precision is the watchword in our lab reports, of course, and here it was soon clear that while the L-509X might look almost identical to the L-590AXII [HFN Apr ’16] its technical performance suggests a merger of the brand’s C-700u/M-700u pre/power [HFN Sep ’15]. Indeed, where the former racked-up a full 2x145W and 2x250W into 8/4ohm, increasing to 165W, 315W and 551W into 8, 4 and 2ohm loads under dynamic conditions, the new L-509X delivers a very similar 2x155W/8ohm and 2x255W/4ohm with a dynamic 183W, 342W and 507W into 8, 4 and 2ohm. With both the M-700u and L-509X, protection limits output to ~300W/1ohm or 16.7A [see Graph 1, below].

 

In similar fashion, the integrated L-509X has –1dB response limits of 3Hz-42kHz (–4.6dB/100kHz) while its 0.02ohm output impedance, rising to 0.05ohm/20kHz and 0.43ohm/100kHz still encourages a slightly earlier roll-off into tougher loads. Distortion is also very low at <0.002% from 20Hz-1kHz before rising gently to 0.03%/20kHz (all at 10W/8ohm). Where the L-509X scores, however, is in maintaining this distortion trend with increasing output, so THD is 0.0025% at 1kHz/1W, 0.0026% at 100W and 0.0034% at the rated 120W. Meanwhile, bearing in mind its high +43.4dB overall gain (balanced input), the A-wtd S/N ratio is a solid 86dB (re. 0dBW) while separation is >80dB midband. PM

Power output (<1% THD, 8/4ohm): 155W 255W
Dynamic power (<1% THD, 8/4/2/1ohm): 183W / 342W / 507W / 278W
Output impedance (20Hz–20kHz): 0.021–0.052ohm
Freq. resp. (20Hz–20kHz/100kHz): +0.0dB to –0.28dB/–4.55dB
Input sensitivity (for 0dBW/120W): 19mV / 212mV (balanced)
A-wtd S/N ratio (re. 0dBW/120W): 85.9dB / 106.7dB
Distortion (20Hz-20kHz, 10W/8ohm): 0.0024–0.033%
Power consumption (Idle/Rated o/p): 102W / 440W (2W standby)
Dimensions (WHD) / Weight: 440x103x463mm / 29.3kg
Price: £8,500