The complaint you hear about capos is that they put the guitar out of tune. That is real, and it is mechanical rather than a defect: pressing a string down stretches it, and a capo that presses harder than necessary — or that drags the strings sideways as it closes — sharpens them.
Every difference that matters between capos comes back to that.
Three mechanisms
Fixed-tension spring — Kyser, Dunlop Trigger
A strong spring squeezes the neck. Squeeze the handle, slide it on, release. One-handed, instant, and it parks on the headstock between songs.
The spring applies the same force regardless of your neck thickness or string gauge, so on some guitars it applies more than is needed and the strings go sharp. There is no adjustment. That is the design.
Kyser publishes aircraft-grade aluminum construction and that the capos are made in the United States. Neither Kyser nor Dunlop publishes a weight or a clamping force.
Adjustable screw — Shubb
A threaded barrel sets how far the over-center lever closes. You set it once for your guitar; the lever then locks at exactly that pressure every time.
Shubb publishes solid brass construction, a custom-engineered roller in the lever mechanism, and a rubber pad designed to work like a fingertip — the point being that the closing action presses straight down rather than pulling the string off center, which is precisely the mechanism that causes drift in spring capos.
Slower to fit and to move. Much better at leaving your tuning alone.
Radius-following — G7th Performance 3
Squeeze to attach, squeeze to release, with the tension set by your hand. The string pad uses what G7th calls Adaptive Radius Technology: it mechanically adapts to the curvature over your strings and fretboard, aiming for even pressure across all six strings at the minimum tension that works.
G7th publishes non-reactive silicone pads at every touchpoint, replaceable ART pads, and a free lifetime warranty with registration. No weight is published.
Mechanism against outcome | Spring | Screw | ART |
|---|
| Set pressure yourself | No | Yes, once | Yes, every time |
| One-handed | Yes | No | Yes, with practice |
| Parks on the headstock | Yes | No | No |
| Follows fretboard radius | Fixed curve | Fixed curve | Adapts |
| Published warranty | Not stated | Not stated | Lifetime, registered |
| Published weight | No | No | No |
Curvature: the variable nobody mentions
A fretboard is not flat. It curves across its width, and the radius differs between instruments — a classical guitar is essentially flat, a vintage-style electric strongly curved, a modern acoustic somewhere between.
A capo bar with the wrong curvature presses hardest on the middle strings and least on the outer ones, which produces buzzing at the edges and sharpening in the middle. It is why a classical capo and a steel-string capo are different products, and it is exactly the problem G7th's adaptive pad is built to solve.
Straight down
The direction a capo should press
A capo that drags the strings sideways as it closes is a capo that pulls the guitar sharp. That is the whole tuning argument in one sentence.
Which to buy
If tuning stability matters most: the Shubb. Set the tension once for your guitar and it does not disturb the tuning.
If speed matters most: the Kyser. One hand, instant, parks on the headstock, and if your guitar does not go sharp under it there is no problem to solve.
If you want one capo forever: the G7th, with the caveat that it costs several times the alternatives and a first capo does not need to.
Placement and pressure matter as much as the capo: how to use a capo covers both.
What we did not doWe have not played any of this gear. Every guide in this category says it tested twenty tuners; we would rather say plainly that we tested none. What we did instead is on this page in full: published specifications with their sources, the makers' own manuals read rather than paraphrased, and a note wherever a company publishes nothing at all.
