The most important difference between Calibre 956/912 and previous Memovox movements is the addition of a case-mounted brass gong. Rather than striking a protuberance on the steel case back, these calibres strike a circular gong mounted to the case back. This design was pioneered by Calibre 919 in 1989. Like other contemporary Jaeger-LeCoultre calibres, 956/912 uses ceramic bearings on it's rotor and has new gear profiles pioneered with "Autotractor" Calibre 975.
Like previous Memovox movements, Calibre 956 has two crowns. The crown at 4 00 is used to set the time and manually wind the mainspring, while the crown at 2 00 is used to wind the alarm and set the alarm time and date. Flush with the case, it winds the alarm barrel, which is not automatically wound otherwise. Pulled out, it can set the alarm time in one direction and the date in the other.
Calibre 956 was introduced in 2008 for the Jaeger-LeCoultre Memovox Polaris. It runs at 28,800 vph, has 23 jewels, and a power reserve of 45 hours thanks to a large variable-inertia balance and ceramic ball bearings. One welcome difference between the Calibre 956 and earlier Calibre 918 and previous Jaeger-LeCoultre alarm calibres is the addition of a quickset date function.
Jaeger-LeCoultre currently uses this calibre in 3 watches: