Marantz SA-KI/PM-KI Ruby SACD Player/Amplifier Sidebar: Class D To The Core

Sidebar: Class D To The Core

Although its literature was less than clear at the time, the PM-10 [HFN Aug '17] was Marantz's first attempt at an audiophile Class D amplifier driven from a switchmode power supply. Its subsequent success was due in no small part to Marantz's choice of Ncore power amp modules and switchmode PSU, both from Hypex. Bridged pairs of NC500 modules were employed in the PM-10, trimmed down to single modules in the KI-PM Ruby, the 200W rating of the former similarly halved to 100W/8ohm here.



Of course, with Hypex rating the modules at 700W/4ohm, the KI-PM Ruby apes the PM-10 by delivering considerably more power into 8 and 4ohm loads than Marantz's specification might suggest. Furthermore, while less sophisticated H-bridge Class D amplifiers suffer from a load-dependent frequency response (changing with your choice of speaker), the single-ended Hypex modules ensure a more consistent and predictable performance [see above for responses into 8, 4, 2 and 1ohm]. PM

Sound United
Shirakawa, Japan
Supplied by: D&M Audiovisual Ltd, UK
02890 279830