PBT vs ABS keycaps: the sound
Updated
PBT keycaps usually sound deeper and more muted, ABS keycaps brighter and higher. Thickness counts as much as the plastic: thick ABS sounds less piercing than thin ABS, and keycaps change the sound less than the switches and the board under them.
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Pick a pack, then press any key or tap the keys below. These are the same samples the app plays.
The two plastics
| ABS | PBT | |
|---|---|---|
| Sound, by RTINGS | “Brighter, higher-pitched ‘click’ or ‘ping’; thinner ABS can sound tinny.” | “Deeper, more muted ‘thock’; feels and sounds more solid.” |
| Density | 1.06–1.08 g/cm³ (Wikipedia) | 1.4 g/cm³, by Epomaker |
| Wear | “prone to shine”, by RTINGS | “isn’t nearly as likely to develop shine over time” |
| Thickness | Usually thinner, though GMK’s ABS sets are “usually thicker than standard ABS sets” | “usually thicker” |
A denser, thicker cap is heavier for the same shape, which is a likely reason it rings lower; that is our inference, and neither source gives measured frequencies for the two plastics.
Thickness and the rest of the board
RTINGS makes two points that are easy to miss. First, “Thicker keycap walls soften the pitch regardless of material, so high-quality thick ABS will tend to sound less piercing.” Second, “keycaps are only a very small portion of a keyboard’s sound signature; the switches used and the keyboard’s internals will have a much greater effect.”
So a set of thick PBT caps will not turn a hollow, unfoamed board thocky on its own. Epomaker lists thick PBT as one of four steps toward thock, beside case foam, lubed stems and a gasket mount; see how to make a keyboard thocky. For a marbly sound it warns the other way: “Very thick PBT muddies the bounce.”
Hear the difference in Teclo’s packs
Two of Teclo’s keyboard packs imitate thick caps, Ivory and Pebble. Knuckle imitates a bright, unlubed build on a steel plate, the opposite end. No pack changes the caps alone, so this is a contrast of whole builds, not a test of keycap plastic:
| Pack | What it imitates | Brightness (Hz) | Low/high (dB) |
|---|---|---|---|
| Pebble | Tactile, lubed, thick caps | 2,370 | -7.8 |
| Ivory | Linear under thick caps | 2,909 | -15.8 |
| Knuckle | Tactile, unlubed, steel plate | 3,653 | -14.7 |
Low/high is the energy below 1 kHz against the energy above it: the higher, the deeper. Pebble has the most low end of any keyboard pack Teclo has. Ivory shows that thick caps alone do not make thock: it stays clean and bright, a marbly clack rather than a thock. Both are synthesized; they imitate the effect of thick caps, not a measured keycap set.
Keycaps are one part of several; why mechanical keyboards sound different goes through the rest, and plate materials covers the part under the switches.
Questions
Are PBT keycaps quieter than ABS?
They sound lower rather than much quieter. RTINGS describes ABS as a "brighter, higher-pitched 'click' or 'ping'" and PBT as a "deeper, more muted 'thock'", and says keycaps are only a small part of a keyboard's sound.
Do thicker keycaps sound deeper?
Yes, by both sources here. RTINGS: "Thicker keycap walls soften the pitch regardless of material." Epomaker suggests caps with 1.4–1.5 mm walls "for warmer pitch".
What about POM keycaps?
RTINGS says POM caps produce "a slightly softer, 'thocky' typing sound" and sit between ABS and PBT in thickness, sound and durability, but are much rarer.
Sources
Other facts on this page come from these pages, read on or before the date above.