What Makes a Switch Thocky
Thock is a low, short, dead sound with no ring after it. Here is what causes it, and which indexed switches have the properties that produce it.
Thock is the sound the hobby organised itself around, and almost nobody defines it. It is a low, short, dead sound: the pitch is low, the note stops immediately, and nothing rings afterwards. The opposite is clack, which is high and bright and lingers slightly.
The useful thing about thock is that it is not a matter of taste. It is a physical outcome of four choices, and you can read three of them off a specification sheet before you buy anything.
Where the sound comes from at all
Almost everything you hear from a keyboard is plastic hitting plastic, twice per keystroke.
The stem falls and strikes the bottom housing. That is the downstroke, and it is the louder of the two. Then the spring pushes the stem back up and it strikes the top housing. That is the upstroke.
So “what makes a switch thocky” is really one question: what makes those two impacts low, short and dead rather than high, bright and ringing.
1. Housing material, which decides pitch
The single largest factor.
Nylon is soft and absorbs impact. It converts more of the collision into heat and less into sound, and what sound remains is lower and stops sooner. Nylon housings, listed as PA66 or PA12, are the foundation of a thocky switch.
Polycarbonate is harder and more brittle. It rings. The same stem falling the same distance into a polycarbonate housing produces a brighter, louder, longer note. This is what makes a switch clacky rather than thocky.
Many switches mix them, most often a polycarbonate top over a nylon bottom. That is a deliberate split: the downstroke stays deep and the upstroke stays bright. It is not a compromise so much as a choice to have both.
2. Travel, and the long pole problem
Here is the part most explanations miss.
A long pole stem is extended so it reaches the bottom housing sooner, shortening the total travel from around 4 mm to 3.5 mm or less. It hits the bottom harder and with a smaller contact area, and the result is a sharp, loud, high bottom-out. Long poles are how the current generation of switches gets its crisp sound, and they are the direct enemy of thock.
So a thocky switch keeps close to the full 4 mm of travel. When a listing says 3.4 mm, that is not simply a shorter key: it is telling you the sound will be sharper.
This is why total travel, which looks like a boring number, is the second thing to read.
3. Weight, which affects how hard it lands
A heavier spring drives the stem into the bottom housing with more force, which is louder, and slightly lower in pitch because more of the housing is set moving. A very light switch can be nylon and full travel and still sound thin, simply because nothing hits anything very hard.
This one is weaker than the first two, and it is also the one you can change afterwards for a few pounds by swapping springs.
4. The board, which is at least half of it
Two identical switches in two different keyboards do not sound alike, and the difference is usually larger than the difference between two switch models.
The case is a box the sound happens inside. A dense aluminium case with foam absorbs and deadens; a hollow plastic case resonates and adds a ring nothing about the switch can remove. The plate matters similarly: polycarbonate and FR4 plates are duller and deeper, brass and steel are brighter.
Which is worth saying plainly, because it saves money: if your board sounds hollow, thocky switches will not fix it. Foam and a softer plate will do more than a new set of switches, and cost less.
What to actually look for
On any listing, in order:
- Housing: nylon, PA66 or PA12, top and bottom. A polycarbonate top is fine if you want some brightness on the upstroke.
- Total travel: 3.8 mm or more. Below 3.6 mm you are looking at a long pole, which is the other sound entirely.
- Weight: 50 gf or above if you want it to land with authority.
- Not silent. Silencing pads remove the impacts, which removes the thock along with the noise. That is the whole trade, covered in silent switches.
Lubrication deepens the sound slightly and removes scratchiness, but it does not turn a clacky switch thocky. Housing and travel decide that before you open the pot.
The rest of the vocabulary
Clacky is the opposite end of the same two variables. Creamy is a different axis entirely, describing smoothness rather than pitch, which is why a switch can be both creamy and thocky, or creamy and clacky.
The mechanism behind all of this is in switch anatomy, and the figures for every switch here are in the index.