Finger Tension
How tension and string height trade off. The three sensations of "feel" respond differently — only the left hand can be tuned with action. Below that, the bridge shows the separate projection lever.
Same strings, walked up the fingerboard. Effort climbs as the string sits higher off the board — the high register always costs more, and a stiffer set widens the gap.
The higher the bridge carries the strings above the top plate, the longer the arm the bow's force pushes on — so the same force rocks the bridge harder over the soundpost. Raise the slider and the whole bridge grows taller from its feet, while the plate flexes a little more under the bass foot. This is separate from tension: as long as the pitch and string length stay the same, the string's tension doesn't change — but the torque on the bridge and top plate still climbs with string height.
Modeled on whichever string you pick above (A by default, since that's where a tension change is felt most). Pressing effort is a first-order estimate (tension × local string height) for comparing setups, not absolute force. The bridge lever is geometry, not tension — and the height that matters there (~88 mm above the plate) dwarfs a fraction-of-a-millimeter action change.
String Set Comparison
Every set in the bench library, by the numbers. Bars show each string's tension on a green→red scale; the dot shows where the price came from.
| Set | Voicing | Tensions (A / D / G / C) | Total | Tier | Price |
|---|
String Combo Builder
Borrow the top from one maker and the bottom from another. The seam to watch is the D→G handoff — a big tension step there reads as a "cliff" under the hand.
Bridge in Motion
A bowed string and the cello bridge it drives. On the left, the Helmholtz kink the bow launches down the string; on the right, the rocking it sets up through the bridge over the soundpost. Strings are C·G·D·A. The motion is schematic and hugely slowed — real bridge travel is on the order of microns.
What the string does — Helmholtz motion
The bow grabs and releases the string (stick–slip), launching a single kink that races to the bridge and back once per cycle. At the bridge that kink reads as a sawtooth force — the engine that drives everything to the right.
What the bridge does — rocking on the geometry
The string's sideways force, applied at its height on the bridge, becomes a torque. The bridge rocks about the stiff soundpost foot, so the bass-bar foot pumps the top — feeding sound into the body. Torque ∝ force × lever arm. The bridge adds no energy of its own: the lever matches the light, fast string to the stiff top, so far more of the bow’s power radiates as sound instead of staying trapped on the string.
Honest caveats: this is the idealized Helmholtz fundamental at roughly 1/100 of real speed. The pitch ratios are true (open A really is ~3.4× faster than open C), but a real A vibrates 220 times a second — far faster than any screen can refresh. Amplitude is the part blown up: real bridge travel is on the order of microns, and a real bridge has its own high resonances this fundamental-only picture leaves out. A teaching schematic, not a measurement.