Marantz Model 40n Streaming Amplifier Lab Report

Lab Report

Unlike Marantz's Model 30 [HFN Jan '21], which employs the same Ncore NC500 Class D power amp module we saw in the PM-KI Ruby [HFN Jan '19] and PM-12SE [HFN Nov '20], the Model 40n sees its Class A/B output stage derived from that used in the PM8006 [HFN Sep '18]. The '40n is a considerably more evolved design, however, for while the PM8006 and '40n are both rated at 70W/8ohm and deliver a very similar 2x95W/8ohm and 2x155W/4ohm, the newcomer – with its paralleled output devices and beefier PSU – steps up with 383W/2ohm and 337W/1ohm under dynamic conditions [Graph 1]. The PM8006 was capped at just 260W/2ohm and 78W/1ohm. Overall gain, too, is similar at +42dB but the '40n enjoys a significantly wider 93.4dB A-wtd S/N ratio (re. 0dBW, vs. 85.6dB for the PM8006) just as distortion is uniformly lower at 0.0004-0.003% (20Hz-20kHz, 10W). The Model 40n's output impedance is fractionally higher at 0.05-0.06ohm (20Hz-20kHz) but its response is just that bit more extended, out to –0.1dB/20kHz and –0.9dB/100kHz.

The performance of the '40n's digital stage is determined, in part, by the choice of ESS's tried-and-tested ES9016K2M DAC implemented here with Marantz's own HDAM op-amps – jitter is fabulously low at <5psec ('Wide' or 'Narrow' lock mode), the A-wtd S/N is an impressive 109dB (via line/record outs) and THD very low at a minimum of 0.00015-0.0004% (20Hz-20kHz) over the top 20dB of its dynamic range [Graph 2]. Two digital filters are offered, with Filter 2 the more broadly 'compatible'. This is a hybrid type with asymmetric pre/post ripples, a 46dB stopband rejection and –0.9dB/20kHz, –3.3dB/45kHz and –6.8dB/90kHz responses with 48kHz, 96kHz and 192kHz media. PM


Dynamic power output versus distortion into 8ohm (black trace), 4ohm (red), 2ohm (blue) and 1ohm (green) speaker loads. Max. current is 18.4A


Distortion versus 48kHz/24-bit digital signal level over a 120dB range (1kHz, black; 20kHz, blue)

Continuous power (<1% THD, 8/4ohm) 94W / 155W
Dynamic power (<1% THD, 8/4/2/1ohm) 117W / 218W / 383W / 337W
Output imp. (20Hz–20kHz, Pre/Amp) 525-661ohm / 0.045-0.062ohm
Freq. response (20Hz–20kHz/100kHz) +0.0dB to –0.1dB/–0.85dB
Digital jitter (48kHz/96kHz) <5psec / <5psec
A-wtd S/N ratio (DAC/Amp, 0dBW) 108.8dB / 93.4dB
Distortion (DAC, 0dBFs/Amp, 10W) 0.0004-0.0007%/0.0004-0.003%
Power consumption (Idle/rated o/p) 50W / 278W (1W standby)
Dimensions (WHD) / Weight 443x130x432mm / 16.7kg
Price £2199

Sound United/D&M Holdings
Kanagawa, Japan
Supplied by: D&M Audiovisual Ltd, UK
02890 279830