New: Lederer Central Impulse Chronometer now in Rose Gold and SS case!

Aug 05, 2023

Bernhard Lederer releases the final two series of his amazing Central Impulse Chronometer – the Series 3 in rose gold and Series 4 in stainless steel.

Press Release with commentary in italics.

The Series 3 and Series 4 of the Lederer Central Impulse Chronometer will retail at CHF 136,800 before taxes.

We have covered the Lederer Central Impulse Chronometer with great enthusiasm since the initial release in Aug 2020, and subsequently in its final form a year later in Aug 2021. The 2021 release comprise of 25 pieces in white gold with a light rhodium dial which formed the Series 1, and the same release also announced the Series 2, which is a 25 piece limited edition in white gold with a deep blue dial. We reviewed the Series 2 in a detailed and comprehensive review here.

The Series 3 and Series 4 are the exact same watch, but in rose gold with a black rhodium dial (which looks dark grey in the release photographs) and in 904L steel with a pacific green dial (which looks blue-green, perhaps bluer than it is green to our eyes) respectively. Only the dial colour and case material is new. Interestingly, the pricing has remained a constant CHF 128k for the entire series. Even for the SS Series 4, Bernhard has kept the pricing at the same level. In our view, this is a much welcomed appropriate pricing strategy. And the Series 4 with its stainless steel case would be our pick.

Bernhard is not out for a money grab by charging CHF 10-20k more for precious metal. After all, most of the interesting work is in the movement itself, and that is what a collector is paying for. The cost difference between a gold case and a stainless steel one is small to negligible. Also, the case and dial are outsourced bits. This contrasts to an alarmingly common practice in the market. We see too many examples of this money-grab and one manufacturer in particular, even charges double for a titanium piece over the base steel piece, despite the fact that they neither make the case nor bracelet of the titanium or steel watches.

After winning the Prix de l’Innovation, the Innovation Awardat the Grand Prix d’Horlogerie de Genève in 2021, this high-performance chronometer with its revolutionary escapement now finds itself housed in a 44mm case available either in a rare 904L steel version with a Pacific Green grey-green open dial, or in an 18K rose gold version with a Black Rhodium grey-black open dial.

Within the case, Bernhard Lederer’s exceptional, multiple-award-winning caliber combines a new type of constant-force escapement with a double gear train. This duality is manifest with two perfectly synchronized seconds hands – a unique and unprecedented development in watchmaking – running in opposite directions within two intertwined apertures that together form a majestic figure eight. The refined craftsmanship and finishing down to the smallest detail further amplify the movement’s architecture and performance, reflecting Bernhard Lederer’s characteristic perfectionism.

Following an admiring reception from experts at the initial presentation of the concept in September 2020 (the first two series were sold within weeks in 2021), Lederer Watches today unveils the two final series of the Central Impulse Chronometer. As with the first two, they are strictly limited to 25 pieces each. Thus is brought to a definitive close what will be known in the history of Haute Horlogerie as one of the most ambitious and challenging chronometric projects of recent decades.

The Lederer Central Impulse Chronometer’s case is 44mm in diameter and 12.2mm in thickness, with two domed crystals to underline the slim silhouette of this horological masterpiece. The first two series brought out in 2021 were both in white gold and had an open dial. These final two come in either pink gold with a galvanically treated black rhodium dial (Series 3) or 904L steel with a “Pacific Green” dial in shades of green and grey (Series 4). The material of the latter is particularly difficult to process, and it is for this reason that most case manufacturers prefer to avoid it. Bernhard Lederer, on the other hand, has overcome this difficulty to give his series a particularly fine luster and rare longevity.

The “8” formed by the two symmetrical circular openings on the exceptional moving mechanism further underline a resolutely artistic vision of the passage of time, dramatized by the two seconds hands synchronously moving in opposite directions. Intertwined, the two circles also convey a symbolic message of harmony, infinity and rebirth, and, in many cultures, of good fortune and prosperity, too.

There is something very special about what Lederer succeeds in doing, this symbiosis between lived watchmaking and “German rigor” which can be recognized and measured in his creations. One sometimes gets the impression that, while most watchmakers might consider that a functional prototype means their work is done, for Lederer, the exciting part of perfecting the product has only just begun.

Near-perfect chronometry – over the entire power reserve

During the prototyping phase, Bernhard Lederer noticed a marginal but nonetheless disturbing fact: Despite the presence of constant-force remontoire in each of the two independent gear trains, the watchmaker noted a slight increase in the oscillation amplitude of the balance towards the end of the movement, inducing a tiny rate deviation in the running rate.

Why was the amplitude increasing at the end of the power reserve? Because, when the torque delivered by the barrel spring weakens, the pressure of the remontoir wheel teeth on the pallets of the remontoir anchor is reduced. De facto, the resistance to winding decreases, so more force is transmitted to the escapement wheel. Ergo, amplitude increases.

To remedy this, Bernhard Lederer re-imagined the remontoire. Traditionally, it is equipped with a saw-toothed wheel. This is what traditional watchmaking treatises had always advocated, so that was the concept Bernhard Lederer spontaneously opted for. But in practice, the watchmaker realized that it was precisely this ‘contact’ between winding wheel and anchor that needed to be modified if the amplitude error associated with the power reserve coming to an end was ever to be totally rectified.

Now, a straight-toothed wheel drives a pinion with a two-armed wing, which is released every 10 seconds by the winding fork for half a rotation.

The result, in terms of chronometric efficiency, was immediate: The triggering resistance was reduced by a factor of 10, as was the ratio between wheel and pinion, which considerably increased the efficiency of the remontoire. Importantly, it rendered the difference in triggering resistance negligible. Today, it is no longer possible to detect or even measure a variation in amplitude, as the Central Impulse Chronometer maintains a constant amplitude throughout the entire movement. Its regularity is quasi-perfect.

Breguet, Daniels, Lederer: the circle is complete

Drawing on almost 40 years of experience and supported by his team in Saint-Blaise near Neuchâtel, Bernhard Lederer took up the torch that George Daniels had lighted with his Independent Double-Wheel Escapement. Daniels himself had taken Breguet’s work a step further by solving the issues this type of escapement was known to have. That is why the Central Impulse Chronometer escapement has a very different design.

It incorporates two independent escapement wheels, each linked to its own barrel. These wheels work in alternation with a unique anchor. Its profile, its rubies, its lifting angles, its central impulse and the way it comes into contact with all the components it guides make this an extraordinary system.

Two escapements, two remontoires

To optimize accuracy, Bernhard Lederer installed the two escapement wheels at the end of two separate gear trains, each equipped with its own 10-second remontoire. By smoothing out the driving force to an extremely fine level, optimizing the geometry of the escapement parts, lightening these energy-hungry components, and reducing escapement friction to a minimum, Bernhard Lederer has achieved a degree of watchmaking perfection rarely seen before. By making the two escapement wheels independent of each other, he has essentially freed them.

This sophistication also shows in the fact that the two seconds hands, each linked to an escapement wheel, are permanently synchronized, something never before seen in the watchmaking industry. They show no drift whatsoever in relation to each other.

Finally, the precision of each watch is such that the behavior of the escapement wheels has been observed with high-speed cameras, tests have been carried out with different materials, and special measuring instruments have been developed to detect and record every amplitude of the balance wheel to obtain absolute definitive results. Each new discovery this process led to was like a door that had never been opened, allowing us to see what had never been seen before. Reason enough to incorporate this new knowledge into the development and refinement of the caliber that animates this collection, which is limited to a total of 100 pieces. Each watch is delivered with a Certificate of Chronometry.

The work of Bernhard Lederer: A unique symbiosis between ‘lived’, empirical watchmaking, and German rigor

The initial inspiration for this project came from George Daniels. Bernhard Lederer had exchanged ideas with him on numerous occasions and set about rethinking his work in depth in order to transpose George Daniels’ brilliant concept of an independent double-wheel escapement – which the master had developed for a pocket watch – into a wristwatch, with all the constraints that implied. Lederer chose a frequency of 3 Hz because the shocks endured by a watch on the wrist have repercussions on the movement’s regulating organs. The latter must therefore resume normal operation as quickly as possible – a sine qua non for precision when a timepiece is worn. For this reason, a frequency of 3 Hz is the most appropriate.

Lightweight materials and constant-force winding: less inertia, improved regularity

One of the innovations of the Central Impulse Chronometer is the choice of lightweight alloys over traditional steel for components.

Lighter and more rigid, such parts have lower inertia. They restart faster and therefore consume less energy. In other words, the impulse given by the escapement wheel to the balance wheel is optimized and disturbances are reduced, ensuring isochronism and, consequently, rate precision.

Energy is transmitted from two barrels by two independent gear trains, each reserved for one of the two escapement wheels. In addition, Bernhard Lederer’s movement features a constant-force remontoire. This device accumulates and stores energy in a spring similar to that of the barrel, but less forcefully. At 10-second intervals, it recharges itself, thus equalizing the driving force supplied – all with a very homogeneous level of torque that ensures that the energy delivered to the balance wheel varies very little.

An optimized anchor for direct impulse

The engineering particularity of the Central Impulse Chronometer escapement also shows in the anchor. This is the watch’s metronome. Here, the geometry of the central pallet has been re-imagined to improve efficiency: Now concave, the anchor has a reduced contact surface and prevents the escapement wheels from recoiling.

The impulse is direct and aligned with the centerline connecting the escapement wheel to the balance wheel – so, it is theoretically perfect. This impulse axis remains constant over time, even at a low balance wheel amplitude. As a result, there is less friction, and the balance wheel receives the energy at the ideal timing for better isochronism and stability.

The elegance of an authentic chronometer

In addition to mastering the technical complexities of watchmaking, Bernhard Lederer is also a keen designer. Each of his creations bears witness to a strong artistic sensibility. And the Central Impulse Chronometer is no exception. The round, 44mm-cases in 5N rose gold (for Series 3) and 904L stainless steel (for Series 4) feature soft, elegant lines. Their slim, polished bezels amplify the sense of a vast dial. Two apertures around the seconds hands offer a view of the caliber 9012, its remontoires and escapements.

On the case back, a second domed sapphire crystal – particularly delicate to machine for this reason – identical to crystal in front. It offers an exceptional view of the caliber 9012’s three-dimensional, symmetrical, oblique and openworked architecture. The barrel, gear, remontoire, escapement and balance bridges are all skeletonized, accentuating the litheness of their geometric shapes.

High-performance steel with a unique luster

For Series 4, the final series, Bernhard Lederer chose a case made from 904L steel. This stainless steel is particularly difficult to work with is therefore rarely offered by most case manufacturers. Those who do appreciate this steel’s particular luster – and its ability longevity to maintain this luster over time.

904L stainless steel is highly corrosion-resistant, much more so than 316L steel, which is most commonly used in watchmaking.

904L belongs to the family of stainless superalloys. It is generally used in the high-tech, space and chemical industries. Its excellent anti-corrosion properties, comparable to those of precious metals derive from its high chromium content. When polished, 904L steel gleams with an exceptional luster. Finally, machining 904L steel requires the utmost rigor, and calls for specific tools and processing methods.

In-house finishing at Ateliers Lederer in Saint-Blaise

The two wide golden barrels contrast with the movement’s finishes. The wheel spokes are tangent curves with a unique profile, a Bernhard Lederer hallmark. The level of finishing is on a par with the engineering prowess represented by the Central Impulse Chronometer. The variety and exceptional execution of hand-finishing displayed here – polishing, beveling (incoming and outgoing angles), graining, engraving, satin-finishing, matte and glossy surfaces – further sublimate the movement’s spectacular three-dimensional architecture.

The Central Impulse Chronometer is a masterpiece of conscientious and discreet watchmaking, its technical excellence and design strength shining through in the accomplished craftsmanship and exceptional finishing. The model is available in two limited series of 25 pieces each, one in 5N rose gold with a black rhodium dial, and the other in 904L stainless steel with a gray-green dial in Pacific Green.

Technical Details

Name: CENTRAL IMPULSE CHRONOMETER

Reference: 9012

Functions: Hours, minutes, small seconds at 8 and 11 o’clock

Case:

Metal: 5N rose gold (25 pieces)

904L stainless steel (25 pieces)

Diameter: 44mm

Thickness: 12.2mm

Case back: Open, sapphire crystal with anti-reflective coating on both sides

Water resistance: 3 ATM

Dial: Guilloché (exclusive Lederer pattern) with two interlaced circles forming a figure eight opening.

Rhodium black on rose gold version; Pacific Green on 904L version

Movement: Mechanical, hand-wound

Number of components: 210

Number of jewels: 45 rubies

Frequency: 21,600 vibrations per hour (3 Hz)

Diameter: 39.3mm

Thickness: 5.98mm

Special features: Double barrels

Two independent gear trains

Two constant-force remontoires

Double wheel escapement with central impulses

Winding & setting: Two-position winding stem:

Position 1: manual winding

Position 2: setting the time

Finishing: Frosted with hand-beveled bridges, wheels with circular

grinding and hand-beveled spokes.

Power Reserve: 38 hours

Retail price : CHF 136,800 (taxes not included)