Luxman L-30 Amplifier Lab Report

Lab Report

Luxman rated this smart-looking amplifier at 2x32W/8ohm and 2x37W/4ohm but the L-30 is actually a little more load-tolerant than this might suggest, delivering closer to 2x40W/8ohm and 2x52W/4ohm while incorporating sufficient headroom to accommodate 55W, 78W and 74W into 8, 4 and 2ohm, respectively, under dynamic conditions. This falls slightly to 60W into 1ohm, equivalent to a maximum 7.8A current at <1% THD – still generous for the era [see Graph 1]. Its other specifications, like the '<0.05% THD at 32W' and '15Hz-50kHz at less than –1dB (response)' are a little vague but the L-30 stands up well enough in practice. Distortion, for example, increases steadily with power output from 0.0035%/1W to 0.018%/10W and 0.035% at the rated 32W (re. 1kHz/8ohm) and with frequency from a minimum of 0.002%/300Hz/1W increasing to 0.008% at 20Hz and 20kHz [see Graph 2, below]. By modern standards, the +39.2dB gain is high, but not excessively so, but the 80dB A-wtd S/N ratio (re. 0dBW) is about 5-6dB adrift.

The L-30's moderate 0.155-0.31ohm output impedance will cause some variation in response, especially at HF, but into a 'flat' 8ohm load it reaches out across a wide 11Hz-44kHz (–1dB), falling to –3.2dB/100kHz. The 'Low Cut' and 'High Cut' filters are specified at 70Hz and 7kHz, respectively, with first-order slopes. The former actually operates below 200Hz, falling to –3dB/100Hz, –6dB/58Hz and –30dB/5Hz and proving more than sufficient to manage the most vigorous of arm/cartridge resonances when partnered with big reflex-loaded speakers. By contrast the 'High Cut' is gentler but offers an effective roll-off of –3dB/6.5kHz, –6dB/11kHz and –10.5dB/20kHz. PM


Dynamic power output vs. distortion up to 1% THD into 8ohm (black trace), 4ohm (red), 2ohm (cyan) and 1ohm (green) speaker loads. Max current is 7.75A


Distortion versus frequency at 1W/8ohm (5Hz-40kHz, black) and 10W/8ohm (20Hz-20kHz, red)

Power output (<1% THD, 8/4ohm) 40W / 52W
Dynamic power (<1% THD, 8/4/2/1ohm) 55W / 78W / 74W / 60W
Output imp. (20Hz–20kHz/100kHz) 0.155-0.31ohm / 1.34ohm
Freq. resp. (20Hz–20kHz/100kHz, 0dBW) –0.35dB to –0.25dB/–3.2dB
Input sensitivity (for 0dBW/32W) 31mV / 178mV
A-wtd S/N ratio (re. 0dBW/32W) 80.4dB / 95.5dB
Distortion (20Hz-20kHz, 10W/8ohm) 0.011-0.022%
Power consumption (Idle/rated output) 11W / 125W
Dimensions (WHD) / Weight 440x160x225mm / 7kg