With the release of the new Audemars Piguet Royal Oak ref. 15500 with a 41 mm case, the 41 mm Royal Oak reference 15400 is now officially discontinued. While many felt that the reference 15400 was not perfect, to us it was a very well balanced Royal Oak in terms of overall proportions and design. When the Royal Oak reference 15400 first came out in 2012, collectors of the brand were critical about the fact that the AP calibre 3120 seemed relatively too small for a 41 mm case size —as it was originally launched for the 39 mm reference 15300—, and that due to that, the date aperture was positioned too far to the left needing a small hash marker to its right. Regardless of the date positioning, the reference 15400 was simply perfect as a more robust Royal Oak still fitted with a quick-set calendar, a screw-down crown, double-baton at 12 o’clock and a display case back.

Nuances Between Preceding Royal Oak 15400 vs. New Royal Oak 15500

With the release of the Audemars Piguet Royal Oak ref. 15500 is important to list all the nuances between this new watch and its predecessor ref. 15400 now phased out and to be discontinued. First, the redesign of the new Royal Oak ref. 15500 follows the release of the new AP automatic movement, calibre 4302 to power the new Audemars Piguet Code 11.59 Date model —more on this topic to follow on a separate article.

The new calibre 4302 is an automatic movement with a larger diameter at 32 mm and more suited for a 41 mm case size. While the automatic AP calibre 3120 seemed to work just fine within the 41 mm Royal Oak case regardless of its 26.6 mm diameter —5.4 mm narrower than the new calibre—, Audemars Piguet mentions that the wider calibre 4302 is more reliable and it provides 10 extra hours of power reserve —70 hours versus 60 on calibre 3120. Turning the watch over reveals a new look on the calibre with a completely different oscillating weight and new architecture. Below you’ll see a picture of calibre 3120 following the new calibre 4302.

With the new Audemars Piguet calibre 4302 also comes greater case thickness but not by much. While both the Royal Oak ref. 15400 and the new Royal Oak ref. 15500 have a case diameter of 41 mm, the ref. 15400 had a thickness under 10 mm at 9.8mm.

The new Royal Oak ref. 15500 is slightly thicker at 10.4 mm. Honestly, the additional 0.6 mm are not perceivable when you hold the two watches side-by-side like we did. We didn’t even bother to take a picture of one watch on top of the other because you really can’t tell that the new Royal Oak ref. 15500 is slightly thicker.

The biggest impact from the new Calibre 4302 on the 41 mm Royal Oak is that the dial had to be redesigned to reposition the date aperture at 3 o’clock. Even though the new dial seems more legible and cleaner, it feels like there’s something missing as the applied markers are wider and shorter than those on the 15400 and the date aperture is bigger and positioned too close to the edge of the dial without a 3 o’clock marker. Something else that catches your eye when looking at the 15400 next to the 15500 is that the applied ‘AP’ logo at 12 o’clock is slightly bigger on the latter.

At first glance, one would think that this is a quartz Royal Oak as the word ‘Automatic’ was removed, making this Royal Oak reference, the first self-winding Royal Oak since 1972 to not bear the ‘Automatic’ designation on its dial. Additionally, both the ‘Audemars Piguet’ name and the minute track had been printed on a smooth finished area and not on the “Grande Tapisserie” pattern. Lastly, the counterweight area on the seconds hand has been skeletonized and the hour and minute hands slightly widened.

The new Royal Oak ref. 15500 —still 41 mm like its predecessor the ref. 15400— is available in stainless steel with blue, slate grey —in reality we perceived no color difference against the ruthenium grey dial on our 15400— or black dial. Additionally, a pink gold model is also available with black dial and the option of pink gold bracelet or black alligator strap. The new Royal Oak 15500 is exclusively available at the AP boutiques.

After perusing both watches at the Salon International de la Haute Horlogerie in Geneva this week, all we can say is that the Royal Oak ref. 15400 is much superior despite the use of calibre 3120 and a watch that will be dearly missed from AP’s lineup. In reality the 15400 is by far a much better looking Royal Oak when compared to the new 15500. With the 15400 phased out and soon to be officially discontinued expect for the secondary market to pick up and prices to go up really fast on any 15400s out there.

Sticker Price $19,200 USD. For more info on Audemars Piguet click here.