The PM-KI Ruby is built with just one aim – audio performance – which is why it uses a fully discrete two-stage design with separate power supplies for the preamplifier and power amp section to reduce interference, and draws on the design of the flagship PM-10 amplifier with its moving coil/moving magnet phono stage and Marantz HDAM technology throughout for signal purity.
The PM-KI is built on a vibration-resistant double-layer chassis for rigidity, with 5mm thick aluminium top lid, solid aluminium front, copper-plated chassis and massive insulators. It’s also equipped with high-quality nickel-plated input terminals and high-purity copper speaker connections.
The PM-KI Ruby features a current feedback design with newly-developed wide-range circuitry and a toroidal transformer dedicated to the pre-amp for clarity and powerful sound. The HDAM® SA3 circuitry offers the cleanest signal path and optimal dynamics through the amplifier, which delivers 100W per channel into 8ohm speakers, or 200Wpc into 4ohm. The audio signal path is made entirely from discrete components for optimal quality, with the RIAA equalization split into passive and active components: RIAA correction is carried out by a Marantz HDAM, while the all-discrete amplification runs in minimum-distortion Class A.
Designed to deliver optimal sound quality by simplifying the signal path, the Marantz Musical Premium Phono EQ stage in the PM-KI amplifier can be used with both moving magnet and low-output moving coil cartridges, thanks to a built-in MC head amplifier. The design is all about lowering distortion by using two-stage amplification, combining Marantz HDAMs with JFETs (junction gate field-effect transistors) in the input stage, giving high input impedance. This allows the no-negative-feedback design to be further simplified by the deletion of coupling capacitors – all then shielded – again reducing distortion and enhancing signal purity.
Laser Engraved Signature
Marantz has been designing and making amplifiers for more than 65 years, and for 40 of those the products have reflected the expertise of Ken Ishiwata. Now, to mark his four decades with the company, the PM-KI Ruby amplifier has been developed and tuned by a highly experienced engineering team led by KI himself. And it arrives bearing Ken Ishiwata’s signature and a special Ruby motif.