Grand Seiko Caliber 9sa4

Grand Seiko Caliber 9SA4

Grand Seiko Caliber 9sa4

ManufacturerGrand Seiko
Caliber Number9SA4, 9SA4A
Base Caliber
Grand Seiko 9SA5
In-House?
Yes
Movement TypeMechanical, manual-wind
Diameter
Unconfirmed
Height
Unconfirmed
Jewel Count
47 jewels
Beat Rate / Frequency
36,000 bph / 5 Hz
Lift Angle
Unconfirmed
Power Reserve
80 hours
Barrel Count
2
Hand-Windable?
Yes
Anti-Shock Device
Diashock
Balance
Free sprung with overcoil hairspring
Escapement
Dual Impulse Escapement
Hand Count4
FunctionsCentral hours; central minutes; central sweeping seconds; power reserve indicator on the back of the movement
Hacking Seconds?
Yes
Country of ManufactureMade in Japan
Known Models
Grand Seiko Evolution 9 Collection (Ref: SLGW002, SLGW003, SLGW004, SLGW005, )(Add your watch to the comments below…)

The Grand Seiko caliber 9SA4 is a handwound mechanical movement with a hi-beat frequency of 5 Hz or 36,000 vibrations per hour. This calibre is found in the Evolution 9 series of Grand Seiko dress watches which were introduced at Watches & Wonders 2024. As a Grand Seiko movement, the 9SA4 is assembled and finished by hand at the Grand Seiko Studio Shizukuishi located in Iwate, Japan.

In Grand Seiko’s own words:

“Caliber 9SA4 was created to provide the ultimate hand-winding experience, with a winding sound and feel demonstrating its craftsmanship and quality. It has a high frequency of 10 vibrations per second, which leads to stable precision, and a long power reserve of up to 80 hours.” –Source

Accuracy Rating:

According to Grand Seiko, the average accuracy of the 9SA4 is -1 to +8 seconds per day in normal operating conditions.

Before the movement is cased, Grand Seiko also tests for a mean daily rate in six positions for 12 days. Under the testing conditions, which are in a controlled environment, the performance is adjusted to -3~+5 seconds per day.

Note: “Mean” is method of calculating the average of a set of numbers. In this case, the set of numbers is the timekeeping in each position, then averaged out over the span of 12 days.

The official user manual for the 9SA4 has a disclaimer stating the following with regards to the mean daily rate: “The specifications are subject to change without prior notice due to product improvement.”

It appears that the specifications did indeed change with regards to the testing duration.

On Grand Seiko’s official 9SA4 page here, it states the following:

“Mean daily rate is a mean value of daily rates in a condition where the movement before assembly in a case is measured in six positions in a fixed manner under artificially controlled environment for 12 days.” –Source (accessed 2/1/25)

In the official manual is states 17 days:

“A mean value of daily rates in a condition where the movement before assembly in a case are measured in 6 positions in a fixed manner under artificially controlled environment for 17 days (20 days for the chronograph).” –Source (accessed 2/1/25)

If you are looking to time your own 9SA4 powered watch, don’t be alarmed if your readings do not immediately align with the timekeeping quotes from GS:

“We specify “target values” for actual use and it is -1 second to +8 seconds per day. To judge the precision of your watch against these values, please measure the gain or loss over a week to ten days, and not just for one day, and in normal conditions.” -Official Operating Instructions (page 24)

What if you run the tests as they specify and still aren’t getting accuracy within their advertised range?

“If the mean daily rate is outside these levels, we recommend adjusting the watch.”

Any needed regulating/adjusting by GS may be covered by the warranty, but bear in mind the following stipulations:

“Adjustment will be chargeable even within the guarantee period if the watch has been subject to any of the conditions below.

  • The watch has been used in ways that are not in line with the recommendations in this booklet, such as allowing it to be magnetized.
  • It has been opened or tampered with by anyone other than a Grand Seiko repair center.
  • It has been damaged as a result of a natural disaster such as a flood, fire or earthquake.
  • Guaranteed conditions have been altered.”

Free-Spring Balance / Dual Impulse Escapement:

The Grand Seiko 9SA4 has a free-sprung balance with overcoil hairspring, working in conjunction with a Dual Impulse Escapement (made with MEMS technology) beating at 10 times per second.

Regarding this configuration, Grand Seiko states:

“As a result, Caliber 9SA4 benefits from the rate stability, resistance to outside interference, and high performance that have long characterized Grand Seiko’s high-beat movements.” –Source

Below is an image of the Free-Sprung Balance and Dual Impulse Escapement (image source):

Grand Seiko Dual Impulse Escapement

Power Reserve:

The caliber 9SA4 is claimed to have a runtime of up to 80 hours on a full wind. According to Grand Seiko, the mainspring requires about 54 turns of the crown to get the watch to a full power reserve. Keep in mind that not everyone winds the crown the same way, so it’s best to consider this number in general terms.

Power Reserve Indicator:

There is a power reserve indicator on the back of the watch to help you determine if the watch is fully wound. At a quick glance the power reserve scale is not very intuitive.

Grand Seiko Caliber 9sa4 Power Reserve Indicator

Of course, one would be able to direction of full and empty based on the movement of the hand upon winding, but apart from that, there are no markings to indicate empty or full. Based on the animation in the video below, it appears that this is the direction of the indicator:

Grand Seiko Caliber 9sa4 80 Hours Power Reserve

9SA4 VS 9SA5:

There is a similar caliber 9SA5 with the main differences being that the 9SA5 is an automatic with a date, compared to the 9SA4 being discussed on this page which is a no-date manual-wind. The main specs, including beat rate, power reserve, jewel count, and accuracy ratings are the same between the 9SA4 and 9SA5. There is an interesting difference:

“The movement achieves a higher winding efficiency thanks to a rearrangement of the gear train and redesign of the parts, so that Caliber 9SA4 achieves a power reserve of 80 hours with 15 percent fewer crown rotations than are required to achieve the same power for Caliber 9SA5 when winding it by hand.” –Source

Note: The official instruction manual covers both of these movements, but also includes the cal. 9SC5, an automatic chronograph movement.

Video:

Examples of watches with this movement:

The 9SA4 powers the Grand Seiko Evolution 9 models.

“Caliber 9SA4 makes its debut in a new dress watch belonging to the Evolution 9 Collection, whose design represents a continuation of the Grand Seiko Style that reaches back to the iconic 44GS of 1967.” –Source

Additional Resources:

Search Assistant: 9AS4, 9SA4B, 95A4

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