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The Encyclopedia of Horology

Movement record · Germany

A. Lange & Söhne Calibre L901.0

Needs research

The manual-wind movement introduced in the Lange 1, the flagship model of the relaunched A. Lange & Söhne after German reunification, notable for its asymmetric dial layout and dual-barrel long power reserve.

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Technical specifications

Diameter
30.60mm (per cited source)
Height
Not fully documented in accessible sources
Jewels
Approx. 53
Frequency
21,600 vph (3 Hz)
Power reserve
Approx. 100 hours (two mainspring barrels)
Winding
Hand wind
Setting
Pull-out crown
Escapement
Swiss-type lever, in-house manufacture
Balance
Screwed gold balance with in-house hairspring in later production
Complications
Outsize date (Grossdatum), Power-reserve indicator

Identification features

  • The movement is characterized by its German-silver three-quarter plate and hand-engraved balance cock.
  • Outsize date display
  • It utilizes a double-barrel system to provide a power reserve of 72 hours.

Known variants

  • Later revised calibres in subsequent Lange 1 generations

Servicing notes

Serviced almost exclusively through A. Lange & Söhne's own service network.

General guidance only. Antique movements should be serviced by a qualified watchmaker.

Historical significance

The defining calibre of Lange's post-reunification revival and a benchmark of the modern German school of finishing.

The manually wound Calibre L901.0 was the first modern movement developed by A. Lange & Söhne and was designed to power the Lange 1 model. The movement features a double-barrel system for consistent power delivery and incorporates traditional elements such as a German-silver three-quarter plate.

The added history summarises the open references listed under Sources; each statement was checked against the cited passage.

Photographs

A. Lange & Söhne caliber L901.0 - WatchBase
A. Lange & Söhne caliber L901.0 - WatchBase — watchbase.com, Rights unverified — web image search result, review pending. Web page (watchbase.com)

Photographs are illustrative examples of the type, not necessarily the exact object described. Verify details against the source file page.

Sources & references

  1. A. Lange & Söhne Lange 1 [Watch Wiki], watch-wiki.net, retrieved 2026-11-04 (paraphrased; text © the publisher)
  2. The Legacy Of Iconic Watch Designs: A. Lange & Söhne Lange 1 - Watch Advice, watchadvice.com.au, retrieved 2026-11-04 (paraphrased; text © the publisher)
  3. A. Lange & Söhne Calibre L901.0 – 5 Watches | Watchflix NYC, watchflixnyc.com, retrieved 2026-11-04 (paraphrased; text © the publisher)
  4. A. Lange & Söhne Lange 1 Ref. 101.025 - lespetitshorlogers, lespetitshorlogers.ch, retrieved 2026-11-04 (paraphrased; text © the publisher)
  5. A. Lange & Söhne literature; precise dimensional specification not independently confirmed here

Where sources disagree, the disagreement is stated rather than resolved silently.