Credor Spring Drive Minute Repeater: The Japanese Strike Back

Seiko is not necessarily what one associate with the highest levels of watchmaking. But the Japanese company has been making headway in the haute horlogerie scene with the Grand Seiko series, particularly the innovative Spring Drive.

The Credor Minute Repeater. Spring Drive movement. Gongs made by Myochin. A sterling example of how the Japanese have adapted the minute repeater invented by the French/Swiss watchmaking tradition and made it one which is utterly Japanese.

The mechanical watches are produced by another division in Morioka. The Spring Drive watches are produced in the Japanese Alps in the city of Shiojiri, where the Seiko Epson factory also builds the famous Epson printers. The factory building is rather massive and they manufacture almost everything in-situ. No official figures are available, but we estimate some 5000 to 6000 pieces of Spring Drive watches are produced each year. Each watch is made atelier style, with one jeweller assembling the case and bracelet, and one watchmaker assembling and performing final finishing and adjustment for the entire movement. An example of this is the Grand Seiko Chronograph Spring Drive we featured here.

But of higher interest to fans of haute horlogerie is the very small atelier within the sprawling grounds. This little atelier is known as the Micro Artist Studio, where some 10 master watchmakers are free to make as they please, and we understand the total production is approximately 10 watches a year. For some reason, the watches produced are branded Credor. The Eichi, which we featured earlier is one example. As is the Sonnerie which is a magnificent example of a Japanese designed and styled petite sonnerie watch.

Out of this very same studio comes the Minute Repeater. The watch is presented as a skeletonized style, sans a regular dial, with the rather gorgeous movement visible under the hands, and also from the back through the sapphire glass.

The movement from the back. The movement bridges are beautifully laid out, and as mentioned, it is wonderfully well finished.

The design is quite interesting. It does not ape the minute repeaters that originate from Switzerland.

Visual design

The design cues are taken from the earlier Sonnerie, with the openwork barrel for the mainspring which is designed in the motif of a bell flower, the symbol of Shiojiri. Elements of a soaring eagle and meandering streams can be found in the sensuous flows of the bridges.

The dial detail of the Credor Minute Repeater. Note the magnificent finish of all aspects of traditional watchmaking craft is performed to the highest levels.
Every bridge is beautifully polished and anglaged, and each inward and outward angle perfectly executed.

Movement – the Spring Drive design

Called the silent revolution, the ingenious Spring Drive combines elements of a quartz based regulation, but still providing the traditional aspects of watchmaking craft. The movement is powered by a regular spring barrel, and power flows through a standard watch wheel train. In a standard watch, the rate in which the wheels spin is controlled by the escape wheel engaging with the balance wheel via the anchor lever. The regulation of rate is achieved by regulating the rate of oscillation of the balance wheel.

In the Spring drive, the fourth wheel (which also drives the second hand as it makes one revolution every minute) does not drive the fifth or escapement wheel but drives a free spinning glide wheel. The regulation system controls the rate of spin of the glide wheel by braking it. The way the brake works on the glide wheel is via contact-less electromagnetic braking. The glide wheel contains a permanent magnet which interacts with a set of electromagnetic brakes. The braking force is generated by the eddy currents within the glide wheel. The beauty of the design is that the same eddy currents also power the electromagnets which acts as the brake. In this way, no battery is required and the system is a closed system, actually powered by the mainspring.

The rate of spin of the glide wheel produces an electromagnetic signature which is compared to a quartz oscillator in the regulation system.  This provides the feedback system to ensure that the glide wheel is spinning at the exact rate to produce good timekeeping of the wheel train. Click here for a video explaination on how this works.

The movement is magnificently finished, every aspect of traditional watchmaking craft finnisage is handled with aplomb. Every part of the movement is finished to the highest traditional level.

Movement – the striking works design

The dial side, showing the finishing and details.
Seen top left, the bell flower representing Shiojiri.
Note the beautifully made teeth of the barrel engaging with the transmission wheel for the power reserve indicator.

As there is no contact between the glide wheel and the brake system, the watch is completely silent, allowing a unique background for a striking watch to shine. This silence of the movement provides an excellent backdrop to the striking works.

The designers at the Micro Artist Studio work with the centuries old family of blacksmiths from the house of Myochin. The Myochin family have, for 2 generations over a period of some 850 years have been at the forefront of the manufacture of wind chimes. These are very traditionally precious instruments and works of art which are highly favoured by the Japanese as gifts. The clear, beautiful tonal structure, and crisp strikes as the gongs of the wind chimes are struck as it is blown by the wind is magnificent, and is the target for the Credor to emulate. The hammers, gongs and strike pins are made by the Munemichi Myochin to try to achieve the unique wind chime sonics.

The movemnt showing the strike hammers made by Myochin. Also can be hinted at in the photograph is the chamber which the gongs reside.

In order to enable the sonics to be clearly heard, the gongs are housed in a separate chamber within the case to allow it full ability to resonate properly. As such, the hammers are not able to strike the gongs directly, but actually strike pins which pierce the chamber and actually make contact with the gongs with each strike of the hammer.

The three armed bridge holding the regulator mechanism. To complement the silence of the Spring Drive mechanism, the striking regulator is designed to be silent as well. The design utilizes air resistance to govern the rate of spin of the regulator, which in turn governs the rate in which the hammers strike the gongs.

Another innovation, though already achieved by Kari Voutilainen earlier is instead of just following on with the hour/quarter/minutes after the quarter strikes in most minute repeaters, the Credor is a decimal repeater. The striking is performed as one would read the time. Click here to hear the chiming of the repeater. Each strike is clean, clear, with a beautiful tonal structure, and decays magnificently over an overall silent background.

Comfortable on the wrist, the case measures 43mm.

This is truly a magnificent product, in our view, the design is truly spectacular, and innovative. The execution and finishing is beyond reproach, and equal of not at a higher level than repeaters made by the Swiss and Germans. We feel it is worthy of the asking price of JPY34,650,000 (approximately US$410,000) and deserves a place in a collection of repeating watches together with Patek Philippe, Philippe Dufour, and Vacheron Constantin. What do you think?