The key to unlocking the appeal of Grand Seiko's latest model, equipped with the manual-winding Caliber 9SA4, is "dialogue with the watch."

The high-beat movement has now become a standard feature of Grand Seiko mechanical watches. The Caliber 9SA series featured in the Evolution 9 collection can be considered the culmination of this movement. In 2024, Grand Seiko added the manual-winding Caliber 9SA4 to the lineup. These two manual-winding models, equipped with the first high-beat manual-winding movement in approximately 50 years, are in fact mechanical wristwatches filled with appeal that transcends conventional boundaries. The key word here is "dialogue with the watch."

Enjoy the pleasure of a hand-wound movement with an optimized 10 vibrations per second

　The Cal. 9SA5, released in 2020, is a movement that embodies a new beginning for Grand Seiko. The combination of a highly efficient dual impulse escapement, a Grand Seiko free-sprung mechanism, and a winding balance spring that ensures high isochronism gives the Evolution 9 collection a practical power reserve of approximately 80 hours, a high vibration frequency of 36,000 vph, and outstanding precision.

　The hand-wound Caliber 9SA4, added in 1924, was born from this masterpiece, the Caliber 9SA5. Many watch manufacturers choose to remove the automatic winding mechanism from their automatic watches and simply wind them manually. This should be sufficient to create a "new dress watch that is uniquely Grand Seiko." However, Grand Seiko changed the design of approximately 40% of the movement components to create the new hand-wound Caliber 9SA4. This was done to optimize it for hand-winding and to provide an excellent winding feel. Grand Seiko wanted to add unique value to the Caliber 9SA while retaining the exceptional fundamental strength of the Caliber 9SA series.

　The result was the "Evolution 9 Collection Hand-Wound Mechanical Hi-Beat 3600080 Hours," equipped with the Caliber 9SA4. It was unveiled at Watches & Wonders Geneva 2024, the perfect venue to showcase the true merits of this new dress watch to the world. To be sure, the high quality and unparalleled character of Grand Seiko's unique winding feel were met with an enthusiastic response, to say the least, from journalists and buyers around the world.

The secret to achieving the best "winding feel" of a mass-produced machine

In creating the first hand-wound Hi-Beat movement in nearly half a century, Grand Seiko's technical team added a requirement that is extremely rare among current models: "dialogue with the watch." Various innovations to improve the winding feel of the crown have given this model an unprecedented individuality.

　Product Planning Manager Kohei Egashira says that the idea of ​​adding a hand-wound movement to the Cal. 9SA series was on the cards from the start of development.

　However, the development team says that they had no intention of creating a movement that simply removed the automatic winding mechanism.

"Today's Grand Seiko has reached a much higher level than before. That's why we wanted to make the manual winding watch something different."

　As the requirements for a hand-wound movement were finalized, the key was emotional value, in other words, enriching the time spent "dialogue with the watch."

　After much discussion about what would create a Grand Seiko-like feel, they decided on a ticking winding feel, which is rare for current models. However, it is difficult to give a ticking winding feel to a wristwatch movement, which has space constraints. This is because there is no space to accommodate the large Kohaze. Yuya Tanaka, who designed the movement, said:

"To clarify the feel, the 9SA4's click spring is about 10 times stronger than that of the hand-wound 9S64. However, it is difficult to design a click spring if it is the rotating type common in ordinary movements. We chose an entirely new sliding click spring to improve the feel, show the movement, and increase durability."

　The development team prototyped four different types of locking mechanism to improve feel and durability. In addition, to make manual winding easier, the rotation speed of the ratchet wheel when winding the crown was increased by approximately 15% compared to the 9SA5.

　However, no matter how much the locking mechanism is improved, it is difficult to expect a good winding feel from the current hand-wound movement. This is because the waterproof gasket built into the crown dulls the feel. "In order to improve the winding feel, the locking mechanism around the 9SA4 was designed with the waterproof gasket in mind," says Tanaka.

　By the way, the winding feel also changes depending on the size of the crown.

"We also adjusted the size of the crown and optimized the torque required for winding. We had about 50 people try winding it, and then we determined the appropriate size based on the torque they gave us."

　The winding stop and power reserve indicator are meticulous considerations typical of Grand Seiko. Previous manual-wound Grand Seiko watches did not have a winding stop when manually wound, to prevent damage to the barrel if it was overwound. In contrast, the 9SA4 has a winding stop, but also adds a power reserve indicator to prevent overwinding. However, Tanaka says that this was also a difficult task.

"The 9SA series has a twin barrel, which means the entrance and exit for the power reserve display are in completely different locations. In addition, there is not enough space, so we could not use a large gear to increase the reduction ratio. So we designed a new tooth profile and put a lot of thought into the layout. However, the space available for the screws that hold the power reserve gear train was quite limited, so we adjusted the position of the screws to within 1/100 of a millimeter," says Tanaka.

　The Cal. 9SA4 is not only a thin, hand-wound movement, but also incorporates the clear philosophy of "dialogue with the watch." Grand Seiko has also given the Evolution 9 Collection Hand-Wound Mechanical Hi-Beat 36000 80 Hours an exterior befitting this special movement.

A new frontier for versatile dress watches

The high-performance Cal. 9SA4 movement has a diameter of 31.0mm, which is by no means small. However, the cases of the SLGW002 and 003 are 38.6mm in diameter and 9.95mm thick, which is comparable to a typical thin dress watch. This was made possible by exploring what a dress watch truly represents Grand Seiko.

　Kohei Egashira said, "In developing this watch, we reassessed what a Grand Seiko dress watch is. In terms of size, we decided to cut the diameter below 40mm and set the ideal thickness at around 9mm." To achieve this size, the inner ring that supports the movement was omitted, and the SLG003 case was made of a special titanium alloy called Brilliant Hard Titanium. Lighter, whiter, with a finer grain and a harder surface, it is extremely compatible with Zaratsu polishing. While this did increase manufacturing costs, the decision was made to use it in order to create the ideal dress watch.

　Additionally, to emphasize the dress watch feel, the indices and hour hand width were narrowed and the dial ring was purposely omitted. To make the case thinner, the case back is screwed down rather than screwed in. Kiyotaka Sakai, who was in charge of the design, said: "But this is Grand Seiko, so we left the minute markers on all the dials."

　The dial design is what identifies it as the Evolution 9. The motif is the same birch as before, but to emphasize the three-dimensional effect, a large birch bark pattern has been incorporated.

　The Evolution 9 Collection Hand-Wound Mechanical Hi-Beat 36000 80 Hours stands out with its specifications of 36,000 vph and approximately 80 hours of power reserve. However, what is even more noteworthy about this watch is its distinctive packaging and statement as a wristwatch. Looking around the market today, it is hard to imagine a hand-wound watch that embodies such a clear, universally relatable message. This is what it means to be unique.