Pre/Power Amplifiers

While the Ncore-inspired Class D power amp at the heart of Mola Mola’s ‘Trajectum’ platform is also utilised in its Kula integrated amp [HFN Oct ’21], the Perca is clearly the product of some fettling in the intervening few years. For starters, while both the Kula and Perca are rated at 2x150W/8ohm and 2x300W/4ohm, the latter nudges about 10W ahead of the integrated model at 2x160W/8ohm and 2x295W/4ohm. However, it’s under dynamic conditions where the significantly greater current delivery/speaker load tolerance of the Perca is revealed [see Graph 1] its 175W, 335W, 443W and 273W at <1% THD into 8, 4, 2 and 1ohm loads, respectively, soaring ahead of the Kula’s mere 175W and 104W into 2 and 1ohm loads. Maximum current is 16.5A versus the Kula’s 10A.

Gain remains a sensibly low +27.7dB in ‘High’ mode and lower still at +21.7dB in ‘Low’ mode while the 88.8dB A-wtd S/N (re. 0dBW) is a little wider than that of the Kula and many other analogue Class D amps. Bass/midrange distortion remains very low at 0.0003% from 1W to 90W increasing to merely 0.01% at 120W, but it does increase above 10kHz, however, to 0.003%/20kHz/10W [see Graph 2]. This is still only half that measured from the Kula but remains in line with the gently tailored response of –0.1dB/20kHz to –4.25dB/100kHz – again still ‘flatter’ than the Kula. Remarkably, the output impedance remains <0.009ohm (<9mohm) from 20Hz-20kHz, so the Perca’s system response [see boxout] is almost entirely immune to swings in loudspeaker impedance. Chalk this up to the ongoing advantage of designer Bruno Putzy’s NCore/Purifi/Eigentakt range of Class D amplifiers. PM