What actually makes a keyboard sound good
Ask five keyboard people what makes a board sound good and you'll get five answers, most of them contradicting each other. The truth is less mysterious than the arguments suggest: a keyboard is an acoustic box, and every part of it changes the sound. Here's what each part does, roughly in order of impact.
The case: the biggest lever
The case is the body of the instrument, and it's the single biggest factor in how a board sounds. A heavy aluminum case gives a dense, full sound with long resonance. A plastic case sounds thinner and higher-pitched, but — and this surprises people — it can sound genuinely good in the right build. Weight matters more than material prestige: mass absorbs vibration, and empty space amplifies it.
That last point is why case foam became standard. An empty case is a hollow box, and hollow boxes echo. Foam between the PCB and the bottom of the case kills that echo and deepens the sound. It's a five-minute mod that changes the sound more than most switch swaps.
The plate: the frame everything vibrates against
The plate holds the switches and sets how rigidly they're mounted. Stiff plates (brass, thick aluminum) transmit vibration directly and sound sharper and louder. Flexible plates (polycarbonate, or no plate at all with PCB-mount switches) absorb energy and sound softer and deeper. Carbon fiber and POM sit in between.
Plate choice also changes feel — a flexible plate gives a softer, bouncier keystroke — so this is one of the few parts where sound and feel move together. If you want a deep sound, a polycarbonate plate is the cheapest meaningful upgrade you can make.
Switches: important, but not the whole story
Switches shape the character of the sound — the sharpness of the bottom-out, the smoothness of the travel — but they operate inside the acoustic environment the case and plate create. A great switch in a hollow, echoing case still sounds hollow. A decent switch in a well-damped, heavy case can sound excellent.
What matters in a switch for sound: long-pole stems (a deeper, fuller bottom-out), factory lubrication (less scratch and spring noise), and tight housings (less rattle). Linear switches are the easiest to make sound good. Tactiles and clickies have more moving parts and more noise sources, which is why the "best sounding" boards are almost always linears.
Keycaps: the last thing the sound passes through
Keycaps are the surface your fingers hit and the last thing the sound passes through, so they color everything. Thick PBT keycaps give the deep, muted tone most people associate with a good-sounding board. Thin ABS sounds higher and clackier — which some people genuinely prefer for a sharper, crisper profile.
Profile matters too: taller profiles like SA or MT3 have more internal volume and sound deeper; shorter profiles like Cherry or XDA sound a bit brighter. The difference between thick PBT and thin ABS is bigger than the difference between any two profiles, so material first, profile second.
Foam, tape, and the cheap mods that actually work
Beyond case foam: the "tape mod" (masking tape on the back of the PCB) slightly deepens the sound by adding mass and damping. Holee modding (tiny pieces of bandage or foam on stabilizer housings) kills stabilizer rattle, which is often the single most annoying sound on a board. Lubricating switches and stabilizers reduces scratch and ticking.
All of these are cheap and reversible. The honest hierarchy: fix your stabilizers first (rattle ruins everything), then case foam, then consider the rest. Most of a board's bad sound comes from a handful of fixable sources, not from needing different parts.
The myth: it's all about the switches
The most common beginner mistake is buying expensive switches for a cheap board and wondering why it still sounds cheap. Switches are maybe a quarter of the equation. The case, the foam, the stabilizers, and the keycaps do the rest. A $30 set of thick PBT keycaps and an hour of stabilizer tuning will improve a budget board's sound more than a $80 switch set dropped into an undamped case.
Bottom line
Sound is a system: case and fill set the foundation, plate tunes the character, switches add detail, keycaps color the result, and stabilizers can ruin all of it if you ignore them. Work in that order — damp the case, fix the stabilizers, then upgrade parts — and you'll get a better-sounding board for less money than someone chasing the perfect switch.