KI Ruby: 40 years at Marantz

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KI Ruby: 40 years at Marantz

Ken Ishiwata is making the transition from guru to a sage now that he has 40 years under his belt with Marantz, the company he went to after getting his start in the industry with Pioneer. Superscope bought Marantz from founder Saul B Marantz in 1964 and moved production to the former Standard Radio facility in Japan. In the next decade they set up Marantz Europe in Belgium but found that they were getting a very high rejection rate with incoming product from Japan. They needed someone who knew about both the business and engineering who could work with the European wing of the company and manufacturing in Japan. Ken Ishiwata first went to Marantz Europe in 1977 but asked for more than they were prepared to pay, in 1978 the company managed to persuade the Japanese wing to pay Ken’s ransom and he moved to Belgium. He’s clearly not just a canny engineer. 

Ken spent three months at the Japanese plant and was surprised by how high the standard of quality control was. Coming from Pioneer he hadn't expected the company to be so rigorous in its QC, nor that every unit would be tested in an industry where sample testing was the norm. Which made it all the more mystifying that they were rejecting so many units in Europe.When he returned to Belgium he discovered that they were using different measurement parameters which had errors that caused perfectly good products to be incorrectly rejected. Ken discovered this by measuring the rejected units and finding that 90% of them were up to spec by the high standards of the manufacturing plant. By acting as an intermediary between the two arms of the company he was able to sort out these problems.

His first products for Marantz were loudspeakers which were made in Belgium using Japanese transducers, he then went on to work on amplifiers. In 1980 Marantz was purchased by Philips a move which allowed Ken to learn a lot about digital audio and resulted in his signature being appended to Marantz CD players from the mid eighties onwards.

KI Ruby
The new KI Ruby anniversary components were demonstrated with Q-Acoustics Concept 500 speakers in a large and well damped room in the basement of the Royal Concertgebouw concert hall, Amsterdam. The speakers toed in to give as wide a sweet spot as possible for the assembled journalists. The main source was a MacBook Pro running Bootcamp and Windows with JRiver Media Centre 23 as the playback software. Running JRiver on Windows on a Mac rather than Audirvana as has been the case in the past is apparently because Windows and JRiver are very popular in Europe, the Mac/Bootcamp element because Ken is a commited Mac user.

Royal Concertgebouw, Amsterdam

As those familiar with the program will know that JRiver is the Photoshop of music (and video) players with many set up options that have a direct influence on sound quality. Ken has apparently listened to most of them and shared some of the more important ones, including his finding that minimum buffering gives best results. The KI approved options are:

WASAPI driver
Load decoded file into memory
Bitstreaming for DSD
Prebuffer: 2 seconds


We listened to a variety of music styles including one piece chosen to reveal the characteristics of the large room which had unusually open highs and clean, even bass. The results were pretty impressive with Sinatra's ‘It was a very good year’ being a stand out, things managed to get more interesting when the source was switched to a Clearaudio built Marantz TT-S1 turntable with MC cartridge running through the phono stage in the PM KI Ruby. It was probably the record, Quincy Jones’ The Dude, or switching to a more central seat further away from the system but this track made a good case for Ken’s assertion that “CD is for business, vinyl is for fun!”

PM & SA Ruby
Following on from the KI Pearl of ten years back the new PM KI Ruby integrated amplifier and and SA KI Ruby SACD player are limited to a production run of 1000 units of each in Europe. With 500 black and 500 gold units carrying serial numbers that reflect the finishes, odd numbers for black even for gold. The PM KI Ruby has a 100 Watt class D output stage and an active preamplifier stage each with its own power supply, making it effectively a pre/power in one box. It has analogue only inputs and a separate headphone amp plus source direct, it also has a rather special phono stage for both MM and MC cartridges. This is a discrete, cascaded design with an initial gain stage for MC that acts like a head amp before the EQ stage, apparently it’s better than the phono stage in the PM-10. Input stages are JFET operated with no coupling caps and the HDAM op-amps in the second stage have been designed without global feedback. It differs from most Class D designs by virtue of putting the feedback after the output filter, a design created by an unnamed Belgian engineer (Bruno Putzeys?) which means that the filter is no longer interacting with the load presented by cable and speaker.

The SA KI Ruby CD/SACD player is where the digital inputs reside, this is both a disc spinner and a DAC and was demonstrated in the latter mode. It has the new Sound United (the parent company) metal drive mechanism which will play DVD-R discs with FLAC, WAV, DSD etc files as well as regular discs. The USB-B input is capable of up to 32-bit/384kHz PCM and DSD246, there is also a USB-A input for thumb drives and phones. The DAC at the heart of this machine uses integer upsampling to convert all incoming PMC signals to DSD prior to conversion. You can choose between sharp and slow roll-off but Ken prefers the former which is naturally the default mode. 
Both KI Ruby units will retail for £3,500 and will be available this month.