the Seneca

Vintage character, modern performance

The easiest way to make a fairly nice mechanical keyboard in the 21st century is to use Cherry MX-style switches. The vast majority of the online hobbyist world—and what most people think of as gamer keyboards—are organized around this off-the-shelf component type. Not the Seneca.

The Norbauer switch architecture is built instead around capacitive sensing, an obscure input technology that emerged in Japan over 40 years ago. Capacitive keyboards were originally designed for longevity in industrial and commercial applications, but latter-day enthusiasts discovered that their structure also gave them a unique and desirable character. A devoted underground subculture of the most discerning collectors grew up around them, despite their rarity and expense. Since our inception, Norbauer & Co. has exclusively served this community.

The elastomeric domes of capacitive keyboards use a controlled collapse at a predetermined inflection point on the downstroke, imparting a satisfying tactile snap. Further, the unusual physical design of the key system (a free-sliding linear bearing, made of resin, which flattens a helical coil against a sensor pad) creates a characteristic and satisfying sound—a deep and quiet acoustic profile sometimes described as a “thock.”

The Seneca takes the architecture of these switches as inspiration but reinvents and reengineers every component from the ground up. This allowed us to construct a keyboard with a fundamentally vintage character, but optimized for all the things that 21st century keyboard enthusiasts have learned can make keyboards sound and feel uniquely pleasurable.

Kinematic optimization, at the bleeding edge of thermoplastic tolerances

Our earliest experiments in creating our own switch taught us that the size of gaps between sliding parts massively affects perceived movement quality. Almost any slop or play gives an unwelcome sense of looseness or “wobble.”

To achieve infinitesimally small gaps between parts, we have chosen to manufacture our components to the very challenging International Tolerance Grade 10 standard, which is very unusual for injection molded parts—especially in consumer electronics. (Even though they are harder to manufacture with precision, we use thermoplastic resins in our switch because they impart an ineffable vintage sound that could never be matched in metal.) We're so obsessive about tolerances that we verify part dimensions with an independent third-party inspection firm using highly accurate 3D computed tomography (CT) scans.

While narrow gaps and tight fits of this kind feel very precise and satisfying, they make a mechanical system highly sensitive to friction. Any over-constraints in the kinematic relationships between the parts will quickly lead to a feeling of sluggishness or even non-functional binding. (For a deeper technical dive into these concepts, you can read my stabilizer design journal here.) Our switch system has therefore undergone rigorous kinematic optimization to ensure that it is constrained with only the minimal amount of friction required to achieve the correct movement pattern. This is why our switches look internally so different from other capacitive keyboards—and why they're so less prone to rotational misalignments of the keycaps.

Our elimination of over-constraints and tolerance ambiguities makes tighter gaps possible without the risk of binding. The result is very tight, smooth, on-axis key travel and fit precision near the limits of what high-end injection molding can achieve.

Projection into a new dimension

Stabilizers are a necessary mechanism to prevent seesaw when long keys (like the spacebar and Shift keys) are pressed anywhere but in their center. Long-key stabilization is a very hard technical problem to solve well, given the tiny working envelope and the competing concerns of mobility and acoustics. It is a problem that has vexed enthusiasts for decades.

Norbauer stabilizers have been awarded multiple patents and are unlike anything else in the keyboard world. Not only do they measurably perform their core anti-seesaw function better than traditional stabilizers, but their acoustic and tactile performance is in a class unto itself.

They uniquely solve the problem of optimizing a linear bearing for sound and feel within a highly constrained sliding envelope. This is done by, in a sense, projecting the travel of the bearing into three-dimensional space, using an intricate folding mechanism to effectively increase the length of the slide. The use of highly precision-ground pins further allows for effectively zero clearance between parts and thus superb acoustic performance without the need for sound-dissipating grease. (For optimally smooth travel feel, we apply a bit of thin-film lubrication anyway.)

For a technical deep dive, check out my talk at KeyCon 2024.

Compliant keycap retention technology

Our patent-pending Aerostem uses compliant “wings” that flex under load to secure Cherry MX-compatible keycap stems without excessive force. Unlike traditional stems that rely on rigid features and crush ribs—causing microscopic abrasion and inconsistent retention over time—the Aerostem redirects plastic relaxation to compliant beams in the switch stem and away from the keycap, preserving keycap interior walls and reducing long-term deformation.

We designed it through extensive FEA simulations, prototyping, and empirical testing to achieve an optimal balance: firm enough to prevent unintentional movement during typing, yet easy to remove without any more force than absolutely necessary. Settling at a comfortable ~3 Newton removal force, the Aerostem creates a satisfying, consistent, and low-friction experience when changing keycaps, with minimal assault to the caps themselves.

Gaskets, dampeners, and preload

The Norbauer acoustic design philosophy is all about dampening. The Seneca's core structure is made of thick, rigid, and dense machined metal elements (such as the housing and solid brass switch plate), which block transmission of internal sound reflections. These are then mediated by soft interstitial acoustic- and vibration-dampening interface layers to prevent any hard surface from touching another and creating noise. Compliant rubber domes and dampening rings against the switch slider further dampen vibrations on the downstroke and upstroke respectively. A natural wool felt acoustic dampener absorbs remaining stray sound waves in the keyboard's interior chamber.

The dampening strategy reaches down to every individual switch. Our switch housings are fully vibration-isolated, held under preload between the switch plate and PCB by the silicone dome flanges and gaskets over-molded onto the switch housings.

The Seneca also ships with a special dampening layer between its helical capacitive coils and PCB. This required greatly amplifying the capacitive sensitivity of our switches, but the result was elimination of the unpleasant "crunch" sound heard in traditional capacitive keyboards as the coil flattens out against the PCB.

No visible structural fasteners or seams

Norbauer keyboards traditionally use a rear cover plate to avoid a seam being visible during normal use. With the addition of new gasketing strategies, we are able to hold the Seneca's rear cover plate onto the housing with less clamping force while still avoiding audible vibrations between the metal parts. This allowed us to develop an internal gantry system that shows zero structural fasteners on any exterior face of the assembled keyboard. The only visible screws are the intentionally cosmetic/decorative ones holding the nameplate in place on the bottom of the keyboard.

An option for good form

Proper typing form avoids a bend at the wrist, allowing one's hand to hover lightly over the keys, ideally with the elbow at a right angle. To support this, the Seneca is designed to support ergonomic use, perfectly flat, without an incline angle.

A wood riser for more traditional typing

For those who are accustomed to and prefer a typing angle (or even a reverse typing angle), the Seneca Wood Riser is available as an optional add-on. It imparts a 3° (or -3°) pitch.

These are precision CNC machined in South Africa from Kiaat, a rare and beautiful teak wood that is native to that country.

Tenkeyless (TKL) layout

The Seneca uses the "tenkeyless" design popular in the enthusiast keyboard world, which omits the redundant number pad to the right of the arrow keys. One advantage of this is locating the mouse closer to the user, which can avoid straining and be easier on the shoulder rotator cuff for long periods of computer use.

Galvanic isolation

In addition to traditional safety measures, the Seneca employs a special galvanic isolation chip, which alone costs more than many entire keyboard PCBs. This "air gap" technology allows for complete electrical isolation of the keyboard and its components from the rest of the computer to which it is connected, preventing surges of current from the USB-C bus from making their way into the keyboard.

High-performance signal processing

Although our focus has never been on gaming (the Seneca is made primarily for people who build and think for a living), our custom-built tech platform nevertheless accommodates users who care about raw performance, with a matrix polling time of <1ms and full N-key rollover at the PCB. We developed our own distinct interrupt-based matrix polling architecture and algorithm to—among other things—facilitate this fast signal detection speed.

Low-friction firmware updates

Should any new features or bug fixes be released in future, our robust Device Firmware Upgrade (DFU) mechanism allows for simple firmware updates without having to worry about flashing firmware yourself or installing any special software on your computer. With a special keypress at boot, the keyboard simply mounts itself as a USB storage device. An update file can be copied onto it as if were on your local file system. On completion of the file transfer, the keyboard will restart itself with the latest firmware version.

At home on Mac, Windows, and Linux

Rare among enthusiast keyboards, the Seneca supports a Mac mode right out of the box, which reconfigures the modfier keys to align with macOS positions without having to do any key remapping in the OS.

Nostalgic boot-up tone

The gentle ”boot-up tone” of the board echoes the sound and excitement of firing up a vintage computer. The PCB uses different tones to indicate macOS and Windows/Linux modes. It can also be turned off entirely. (Hear the sounds in the typing test video above.)

Connectors from Lemo in Switzerland

Lemo connectors are precision machined brass assemblies, traditionally used in high-demand avionics and medical applications. They click pleasingly into place to form a positive lock that prevents accidental disconnection. The Seneca uses a Lemo port at the keyboard and a Lemo plug on the proximal end of its cables.

These are not proprietary connectors; many custom cable vendors in the keyboard world can make cables that are compatible with the Seneca.

USB-C with bespoke overmold

Our custom cables come with USB-C at the distal end for wide compatibility with contemporary computing devices, overmolded with a strain relief in our own custom retrofuturist design.