Mola-Mola Kula Integrated Amplifier Lab Report

Lab Report

Mola-Mola's NCore-inspired Class D power amp section did meet its 150W/8ohm specification but fell short of delivering 300W/4ohm unless under dynamic conditions where 155W, 300W, 175W and 104W was delivered at <1% THD into 8, 4, 2 and 1ohm loads, respectively. Maximum current is limited to ~10A [see Graph 1]. Gain is a sensibly low +28dB (instead of the +40dB offered by many integrateds), the 88dB A-wtd S/N (re. 0dBW) is rather wider than achieved by most analogue Class D amps, and bass/midrange distortion remains very low at 0.0004% up to 10W, increasing to merely 0.002% at 100W [see Graph 2].

Distortion increases more rapidly above 10kHz, however, to 0.015%/20kHz/10W, in line with the tailored response of –0.5dB/20kHz to –3.75dB/60kHz. Incidentally, THD is also higher, watt-for-watt, under dynamic conditions as Graph 1 vs. Graph 2 illustrates. Remarkably, the output impedance remains <0.005ohm (<5mohm) from 20Hz-20kHz, so the Kula's system response is almost entirely immune to swings in loudspeaker impedance. Chalk-up another advantage to designer Bruno Putzy's NCore/Purifi range of Class D amplifiers.

The Kula DAC module is clearly derived from the Makua/ Tambaqui [HFN Aug '17 & Nov '19] but could only be tested here via the main outputs (thus including the Class D pathway). At 2V output, low-level linearity is true to within ±0.4dB over a 110dB range even though the S/N is reduced to 84dB. Distortion, too, is remarkably low at 0.00005-0.0005%/1kHz over the top 30dB of its range, increasing to 0.0009-0.003%/20kHz as a function of the Class D amp. Jitter is incredibly low: less than 25psec, all sample rates/all inputs, through the DAC/amp signal path. PM


Dynamic power output versus distortion into 8ohm (black trace), 4ohm (red), 2ohm (blue) and 1ohm (green) speaker loads. Max. current is 10.2A


Distortion versus frequency versus power output (1W/8ohm, black; 10W, pink; 100W, red)

Continuous power (<1% THD, 8/4ohm) 150W / 285W
Dynamic power (<1% THD, 8/4/2/1ohm) 155W / 300W / 175W / 104W
Output imp. (20Hz–20kHz/100kHz) 0.004-0.001ohm / 0.10ohm
Freq. response (20Hz–20kHz/100kHz) +0.02dB to –0.50dB/–5.0dB
Digital jitter (USB / S/PDIF) 25psec / 25psec
A-wtd S/N ratio (Digital/Analogue) 84.3dB (0dBFs) / 88.0dB (0dBW)
Distortion (DAC, 0dBFs/Amp, 10W) 0.00006-0.002%/0.00025-0.015%
Power consumption (Idle/rated o/p) 57W / 497W (1W standby)
Dimensions (WHD) / Weight 420x110x370mm / 11kg
Prices £9900 (+£5999, DAC; +£1799, MM/MC phono)

The Netherlands
Supplied by: Sound Design Distribution Ltd, Cardiff
0800 0096213