ZENITH
The Zenith El Primero: The Beating Heart of Precision and Heritage
Few names in watchmaking resonate with such reverence as El Primero. More than just a movement, it represents a turning point in horological history — a bridge between tradition and innovation, between resilience and reinvention. When Zenith unveiled the El Primero in 1969, it didn’t merely introduce an automatic chronograph; it created an enduring symbol of mechanical mastery that continues to define the brand more than five decades later. This is the story of how the El Primero came to life, survived near extinction, and evolved into one of the most celebrated mechanical movements ever created.
ZENITH Manufacture
A Race Against Time: The Origins of the El Primero
In the early 1960s, the mechanical chronograph stood as the ultimate expression of precision watchmaking. But there was one frontier left unexplored: automatic winding. For decades, chronographs remained hand-wound — intricate, beautiful, but bound by the limits of daily manual winding.
By 1962, Zenith had already set its sights on the impossible: developing the world’s first fully integrated automatic chronograph movement. This was not to be a modular mechanism bolted onto an existing calibre, but a holistic design — elegant, efficient, and uniquely Zenith. The internal project name was 3019 PHC, and the team’s goal was to unveil it in 1965, coinciding with Zenith’s centenary.
Yet the challenge was immense. Across Switzerland, other giants were working toward the same goal. Heuer-Leonidas, Breitling, Dubois-Depraz, and Hamilton-Büren joined forces on a secret project known as Project 99. Meanwhile, Seiko in Japan was also preparing an automatic chronograph for release. It was a global horological arms race.
Zenith, however, approached the challenge differently. While its competitors sought modularity, Zenith pursued integration — an approach that would yield a more compact, balanced and ultimately more durable calibre. After seven years of development, the result was revealed on January 10, 1969: El Primero — Spanish for “The First”.
In the early 1960s, the mechanical chronograph stood as the ultimate expression of precision watchmaking. But there was one frontier left unexplored: automatic winding. For decades, chronographs remained hand-wound — intricate, beautiful, but bound by the limits of daily manual winding.
By 1962, Zenith had already set its sights on the impossible: developing the world’s first fully integrated automatic chronograph movement. This was not to be a modular mechanism bolted onto an existing calibre, but a holistic design — elegant, efficient, and uniquely Zenith. The internal project name was 3019 PHC, and the team’s goal was to unveil it in 1965, coinciding with Zenith’s centenary.
Yet the challenge was immense. Across Switzerland, other giants were working toward the same goal. Heuer-Leonidas, Breitling, Dubois-Depraz, and Hamilton-Büren joined forces on a secret project known as Project 99. Meanwhile, Seiko in Japan was also preparing an automatic chronograph for release. It was a global horological arms race.
Zenith, however, approached the challenge differently. While its competitors sought modularity, Zenith pursued integration — an approach that would yield a more compact, balanced and ultimately more durable calibre. After seven years of development, the result was revealed on January 10, 1969: El Primero — Spanish for “The First”.
ZENITH Vintage Advert
The First of Its Kind
The El Primero calibre 3019 PHC represented a revolution in chronograph engineering. It was the first integrated automatic chronograph movement, and to this day, one of the most refined ever produced.
Its technical specifications were astonishing for the era:
• High frequency: 36,000 vibrations per hour (5 Hz), enabling measurement to 1/10th of a second.
• Column-wheel chronograph: ensuring crisp, precise push-button engagement.
• Integrated design: automatic winding rotor built directly into the movement, not added as a module.
• Compact thickness: just 6.5 mm — exceptionally thin for a chronograph.
• Power reserve: 50 hours, impressive given the high frequency.
• Date display: integrated without compromising chronograph function.
Where others sought efficiency, Zenith achieved elegance. The El Primero wasn’t just functional — it was beautifully finished, with perlage, Côtes de Genève, and a symmetry that delighted watchmakers and collectors alike.
In 1969, Zenith released the first watches powered by the new movement: the A384, A385, and A386. Of these, the A386 — with its tri-color subdials and restrained 38 mm case — became a design icon, one that remains emblematic of Zenith’s spirit to this day.
The El Primero calibre 3019 PHC represented a revolution in chronograph engineering. It was the first integrated automatic chronograph movement, and to this day, one of the most refined ever produced.
Its technical specifications were astonishing for the era:
• High frequency: 36,000 vibrations per hour (5 Hz), enabling measurement to 1/10th of a second.
• Column-wheel chronograph: ensuring crisp, precise push-button engagement.
• Integrated design: automatic winding rotor built directly into the movement, not added as a module.
• Compact thickness: just 6.5 mm — exceptionally thin for a chronograph.
• Power reserve: 50 hours, impressive given the high frequency.
• Date display: integrated without compromising chronograph function.
Where others sought efficiency, Zenith achieved elegance. The El Primero wasn’t just functional — it was beautifully finished, with perlage, Côtes de Genève, and a symmetry that delighted watchmakers and collectors alike.
In 1969, Zenith released the first watches powered by the new movement: the A384, A385, and A386. Of these, the A386 — with its tri-color subdials and restrained 38 mm case — became a design icon, one that remains emblematic of Zenith’s spirit to this day.
ZENITH Vintage Advert
Crisis and Preservation: The Hidden Years
The triumph of 1969 was short-lived. The 1970s brought the Quartz Crisis, and with it, an existential threat to traditional watchmaking. In 1971, Zenith was acquired by Zenith Radio Corporation, a U.S. electronics company whose management saw the future not in mechanical watches but in quartz technology. Production of mechanical movements was ordered to cease. For the El Primero, this meant death — or so it seemed.
In 1976, an instruction came down from management: destroy the presses, plans, and components for mechanical movements. But one man refused to comply. Charles Vermot, a senior watchmaker who had worked on the El Primero project from the beginning, understood that this calibre was too important to erase.
Quietly, Vermot defied orders. Over the course of weeks, he carefully catalogued and packed away hundreds of tools, dies, cams, and technical drawings. He stored them in the attic of Zenith’s Le Locle manufacture, meticulously labelled and hidden from view. For years, no one knew they were there — but thanks to his foresight, the El Primero would one day live again.
The triumph of 1969 was short-lived. The 1970s brought the Quartz Crisis, and with it, an existential threat to traditional watchmaking. In 1971, Zenith was acquired by Zenith Radio Corporation, a U.S. electronics company whose management saw the future not in mechanical watches but in quartz technology. Production of mechanical movements was ordered to cease. For the El Primero, this meant death — or so it seemed.
In 1976, an instruction came down from management: destroy the presses, plans, and components for mechanical movements. But one man refused to comply. Charles Vermot, a senior watchmaker who had worked on the El Primero project from the beginning, understood that this calibre was too important to erase.
Quietly, Vermot defied orders. Over the course of weeks, he carefully catalogued and packed away hundreds of tools, dies, cams, and technical drawings. He stored them in the attic of Zenith’s Le Locle manufacture, meticulously labelled and hidden from view. For years, no one knew they were there — but thanks to his foresight, the El Primero would one day live again.
Charles Vermot
The Revival: El Primero’s Second Life
By the early 1980s, the watch industry had begun to rediscover the beauty of mechanical timekeeping. Demand for automatic chronographs returned, but few brands retained the expertise or tooling to produce them. Zenith, as it turned out, was uniquely positioned — thanks to Vermot’s secret cache.
In 1984, Zenith’s management rediscovered the preserved tools and documentation. Production of the El Primero restarted, marking one of the great comebacks in watchmaking history. Within a few years, the calibre would find itself powering not just Zenith watches, but one of the most prestigious chronographs in the world.
By the early 1980s, the watch industry had begun to rediscover the beauty of mechanical timekeeping. Demand for automatic chronographs returned, but few brands retained the expertise or tooling to produce them. Zenith, as it turned out, was uniquely positioned — thanks to Vermot’s secret cache.
In 1984, Zenith’s management rediscovered the preserved tools and documentation. Production of the El Primero restarted, marking one of the great comebacks in watchmaking history. Within a few years, the calibre would find itself powering not just Zenith watches, but one of the most prestigious chronographs in the world.
Technical Drawing - 1968
The Rolex Connection: El Primero in the Daytona
In 1988, Rolex was preparing to update its iconic Cosmograph Daytona with an automatic movement. After extensive testing, Rolex selected Zenith’s El Primero as the foundation for its new calibre — a decision that validated Zenith’s engineering excellence.
Rolex modified the movement to meet its own rigorous standards:
• Reduced frequency from 36,000 vph to 28,800 vph for increased longevity.
• Reworked components for enhanced robustness and shock resistance.
• Simplified finishing and adjusted lubrication systems.
The result was the Rolex Calibre 4030, which powered the Daytona from 1988 until 2000. This partnership not only revived Zenith’s prestige but also introduced the El Primero’s DNA to a new generation of collectors. When Rolex transitioned to its in-house calibre 4130 in 2000, the El Primero had already achieved legendary status — recognised as one of the greatest chronograph movements ever built.
In 1988, Rolex was preparing to update its iconic Cosmograph Daytona with an automatic movement. After extensive testing, Rolex selected Zenith’s El Primero as the foundation for its new calibre — a decision that validated Zenith’s engineering excellence.
Rolex modified the movement to meet its own rigorous standards:
• Reduced frequency from 36,000 vph to 28,800 vph for increased longevity.
• Reworked components for enhanced robustness and shock resistance.
• Simplified finishing and adjusted lubrication systems.
The result was the Rolex Calibre 4030, which powered the Daytona from 1988 until 2000. This partnership not only revived Zenith’s prestige but also introduced the El Primero’s DNA to a new generation of collectors. When Rolex transitioned to its in-house calibre 4130 in 2000, the El Primero had already achieved legendary status — recognised as one of the greatest chronograph movements ever built.
Rolex Daytona 16520 - source: 41watch
Technical Anatomy: Why the El Primero Endures
At the heart of the El Primero’s legacy is its architecture. While many movements of its time relied on modular constructions, the El Primero was conceived from the ground up as a complete entity. This integration gives it a distinct tactile signature: a smooth, crisp chronograph start and reset, powered by a column wheel and horizontal clutch system.
The high frequency of 5 Hz allows for remarkable precision. While most chronographs of the 1960s and even today operate at 4 Hz (28,800 vph), Zenith’s movement beats faster, offering finer resolution and improved stability against shocks and positional variations.
Zenith’s mastery lay not only in achieving this frequency, but doing so reliably — ensuring that the high oscillation rate didn’t compromise power reserve or durability. Even today, few manufacturers dare to operate mechanical chronographs at 36,000 vph.
At the heart of the El Primero’s legacy is its architecture. While many movements of its time relied on modular constructions, the El Primero was conceived from the ground up as a complete entity. This integration gives it a distinct tactile signature: a smooth, crisp chronograph start and reset, powered by a column wheel and horizontal clutch system.
The high frequency of 5 Hz allows for remarkable precision. While most chronographs of the 1960s and even today operate at 4 Hz (28,800 vph), Zenith’s movement beats faster, offering finer resolution and improved stability against shocks and positional variations.
Zenith’s mastery lay not only in achieving this frequency, but doing so reliably — ensuring that the high oscillation rate didn’t compromise power reserve or durability. Even today, few manufacturers dare to operate mechanical chronographs at 36,000 vph.
ZENITH El Primero 3610 Movement
Evolution Through the Decades
Over time, the El Primero evolved into a family of calibres, each one building on the DNA of the 1969 original.
Calibre 400 (The Classic Heir)
The direct descendant of the 3019 PHC, the calibre 400 retained the essential architecture — high frequency, column-wheel control, and automatic winding — while improving manufacturing precision and reliability. This movement powered numerous Zenith chronographs throughout the 1990s and 2000s, including the celebrated Chronomaster line.
Calibre 405 (The Flyback Era)
Introduced in the late 1990s, the calibre 405 added a flyback function, allowing the chronograph to be reset and restarted instantly — ideal for aviators and sports timing. Despite the added complexity, the movement maintained its 5 Hz beat and robust automatic winding system.
Calibre 410 (The Triple Calendar Chronograph)
One of the most admired El Primero variations, the calibre 410 incorporated a full calendar and moonphase display into the classic chronograph layout. It became a signature complication for Zenith, marrying practicality and poetry in mechanical form.
Calibre 3600 (The Modern Masterpiece)
To mark the 50th anniversary of El Primero in 2019, Zenith introduced the calibre 3600. This new-generation movement retains the hallmark 36,000 vph frequency but brings modern enhancements:
• Extended power reserve to 60 hours
• Hacking seconds for precise time setting
• Redesigned gear train and escapement for improved efficiency
• 1/10th second chronograph indication on the dial
It debuted in the Chronomaster Sport, instantly hailed as a modern icon — bridging the spirit of the A386 with 21st-century performance.
Calibre 9004 (El Primero 21 – The Future of High Frequency)
Zenith didn’t stop at 1/10th of a second. With the Defy El Primero 21, the brand unveiled a chronograph capable of measuring 1/100th of a second, driven by a second escapement oscillating at 360,000 vph (50 Hz) — ten times faster than the original.
To manage this, Zenith engineered a dual-escapement architecture, separating timekeeping (36,000 vph) from chronograph timing (360,000 vph). When the chronograph is activated, the central hand spins around the dial once per second — a mesmerizing display of kinetic energy.
This calibre demonstrates how the El Primero continues to evolve — from a movement of the 1960s into one that defines the forefront of modern horology.
Over time, the El Primero evolved into a family of calibres, each one building on the DNA of the 1969 original.
Calibre 400 (The Classic Heir)
The direct descendant of the 3019 PHC, the calibre 400 retained the essential architecture — high frequency, column-wheel control, and automatic winding — while improving manufacturing precision and reliability. This movement powered numerous Zenith chronographs throughout the 1990s and 2000s, including the celebrated Chronomaster line.
Calibre 405 (The Flyback Era)
Introduced in the late 1990s, the calibre 405 added a flyback function, allowing the chronograph to be reset and restarted instantly — ideal for aviators and sports timing. Despite the added complexity, the movement maintained its 5 Hz beat and robust automatic winding system.
Calibre 410 (The Triple Calendar Chronograph)
One of the most admired El Primero variations, the calibre 410 incorporated a full calendar and moonphase display into the classic chronograph layout. It became a signature complication for Zenith, marrying practicality and poetry in mechanical form.
Calibre 3600 (The Modern Masterpiece)
To mark the 50th anniversary of El Primero in 2019, Zenith introduced the calibre 3600. This new-generation movement retains the hallmark 36,000 vph frequency but brings modern enhancements:
• Extended power reserve to 60 hours
• Hacking seconds for precise time setting
• Redesigned gear train and escapement for improved efficiency
• 1/10th second chronograph indication on the dial
It debuted in the Chronomaster Sport, instantly hailed as a modern icon — bridging the spirit of the A386 with 21st-century performance.
Calibre 9004 (El Primero 21 – The Future of High Frequency)
Zenith didn’t stop at 1/10th of a second. With the Defy El Primero 21, the brand unveiled a chronograph capable of measuring 1/100th of a second, driven by a second escapement oscillating at 360,000 vph (50 Hz) — ten times faster than the original.
To manage this, Zenith engineered a dual-escapement architecture, separating timekeeping (36,000 vph) from chronograph timing (360,000 vph). When the chronograph is activated, the central hand spins around the dial once per second — a mesmerizing display of kinetic energy.
This calibre demonstrates how the El Primero continues to evolve — from a movement of the 1960s into one that defines the forefront of modern horology.
ZENITH El Primero 21 Movement
Design and Heritage: The Face of El Primero
While the movement is its heart, Zenith’s El Primero watches are also defined by their distinctive design language. The tri-color subdials of the 1969 A386 remain a visual signature, often replicated in modern models as a nod to the past.
In the modern Chronomaster Original, these design codes are meticulously preserved — the overlapping subdials, the red central chronograph hand, and the vintage-inspired typography — all powered by the latest calibre 3600. Meanwhile, the Defy 21 represents the avant-garde side of Zenith, showcasing the calibre 9004 through skeletonized architecture and futuristic materials like titanium and carbon.
This duality — heritage and innovation — defines Zenith today. Each El Primero watch embodies both where the brand has been and where it’s going.
While the movement is its heart, Zenith’s El Primero watches are also defined by their distinctive design language. The tri-color subdials of the 1969 A386 remain a visual signature, often replicated in modern models as a nod to the past.
In the modern Chronomaster Original, these design codes are meticulously preserved — the overlapping subdials, the red central chronograph hand, and the vintage-inspired typography — all powered by the latest calibre 3600. Meanwhile, the Defy 21 represents the avant-garde side of Zenith, showcasing the calibre 9004 through skeletonized architecture and futuristic materials like titanium and carbon.
This duality — heritage and innovation — defines Zenith today. Each El Primero watch embodies both where the brand has been and where it’s going.
Zenith Chronomaster Original
Why the El Primero Still Matters
In an age of digital precision, why does the El Primero continue to captivate collectors and connoisseurs? Because it tells a story of passion, precision, and perseverance. Because it represents authentic mechanical artistry — a movement conceived not for convenience, but for excellence. Because it stands as proof that human ingenuity can transcend obsolescence.
Every tick of an El Primero is a heartbeat from 1969 that still echoes today. It’s a reminder that true innovation is not just about technology, but about courage — the courage to pursue perfection when the world is rushing toward simplicity.
In an age of digital precision, why does the El Primero continue to captivate collectors and connoisseurs? Because it tells a story of passion, precision, and perseverance. Because it represents authentic mechanical artistry — a movement conceived not for convenience, but for excellence. Because it stands as proof that human ingenuity can transcend obsolescence.
Every tick of an El Primero is a heartbeat from 1969 that still echoes today. It’s a reminder that true innovation is not just about technology, but about courage — the courage to pursue perfection when the world is rushing toward simplicity.
ZENITH Defy Double Tourbillon & Defy Zero-G
The Legacy of a Legend
From the race to create the first automatic chronograph to its near extinction during the quartz crisis, from the hidden attic in Le Locle to the wrists of modern collectors — the El Primero’s journey is a tale unlike any other in watchmaking.
It is both a technical marvel and a cultural treasure:
• The first integrated automatic chronograph.
• one of the longest-running automatic integrated chronograph movements still in production (with its core architecture intact since 1969)
• The beating heart of Zenith’s identity for over half a century.
In an industry that thrives on constant reinvention, the El Primero stands as a timeless reminder that some innovations never fade — they evolve, they inspire, and they endure. Zenith may have named it El Primero — “The First” — but for many watch enthusiasts, it remains simply The One.
From the race to create the first automatic chronograph to its near extinction during the quartz crisis, from the hidden attic in Le Locle to the wrists of modern collectors — the El Primero’s journey is a tale unlike any other in watchmaking.
It is both a technical marvel and a cultural treasure:
• The first integrated automatic chronograph.
• one of the longest-running automatic integrated chronograph movements still in production (with its core architecture intact since 1969)
• The beating heart of Zenith’s identity for over half a century.
In an industry that thrives on constant reinvention, the El Primero stands as a timeless reminder that some innovations never fade — they evolve, they inspire, and they endure. Zenith may have named it El Primero — “The First” — but for many watch enthusiasts, it remains simply The One.
Find Your ZENITH El Primero at Michael Jones Jeweller
As an authorised retailer of ZENITH watches, Michael Jones Jeweller is the premier destination for watch collectors in Banbury. Whether you’re looking for a ZENITH watch, Swiss-Made watches, or the latest automatic watches, our expert team can guide you to the perfect timepiece.
Visit us in-store to experience the extraordinary ZENIHT El Primero or explore our selection of Swiss-made watches online.
Michael Jones Jeweller – Premier watch specialists of Northampton & Banbury
