How to Change Keyboard Sound by Swapping Plates: The Ultimate Material Guide

You’ve spent hours researching switches. You’ve painstakingly lubed every stabilizer. Yet, when you finally type on your custom build, the sound is... underwhelming.

It’s a frustration every enthusiast faces. You want that deep, resonant "thock," but you’re stuck with a high-pitched metallic ping. The culprit isn't usually your switches; it's often the backbone of your keyboard: the plate.

In this keyboard plate material guide, we are going to demystify the science of sound. By comparing the three most popular materials—Polycarbonate (PC), FR4, and Aluminum—we will show you exactly how to tune your board to perfection.

To ensure these results are practical, we conducted our tests using the NPKC RO75 PRO Mechanical Keyboard. Its modular design allows for rapid plate swapping, making it the perfect candidate to demonstrate the dramatic differences in acoustics.

Why Your Plate Matters: The Physics of Sound

Before we dive into the materials, we need to understand why the plate changes the sound at all. When a switch hits the bottom of its travel (bottom-out), it creates a vibration.

The plate holds the switches in place. Therefore, the plate is the primary medium that transfers or absorbs that vibration.

Think of it like a guitar body. A metal guitar sounds bright and sharp. A wooden guitar sounds warm and resonant. Keyboard plates work similarly. The density and flexibility of the material dictate whether your keyboard will sound "Clacky" (high-pitched and crisp) or "Thocky" (deep and muted).

However, it’s not just about sound. The feel changes too. A stiff plate offers a solid bottom-out feel, while a flexible plate provides a softer, cushioned typing experience.

The Contenders: PC vs FR4 vs Aluminum

Let's break down the three titans of the custom keyboard world.

1. Aluminum (The Standard)

Aluminum is the most common stock plate found in pre-built keyboards. It is rigid, durable, and relatively cheap to manufacture.

Sound Profile: High-pitched, clacky, and resonant. Because metal is stiff, it reflects high-frequency sounds rather than absorbing them.

Best For: Users who want a consistent, firm typing feel and prefer higher-pitched "pop" sounds. It is also excellent for tactile switches as the rigidity emphasizes the tactile bump.

2. Polycarbonate / PC (The Thock King)

If you are looking for the best plate for thock, Polycarbonate is usually the answer. It is a soft plastic that is highly flexible.

Sound Profile: Deep, muted, and bass-heavy. The soft material absorbs high-pitched frequencies, leaving only the lower tones. This creates the coveted "thocky" sound signature.

Best For: Linear switches and gasket-mounted builds like the NPKC RO75 PRO, where flex is desired.

3. FR4 (The Balanced Choice)

FR4 is the same material used to make Printed Circuit Boards (PCBs). It is a composite of woven fiberglass and epoxy resin.

Sound Profile: It sits right in the middle. It is deeper than aluminum but brighter than Polycarbonate. It offers a "poppy" sound that is very satisfying.

Best For: Those who can't decide. It provides enough flex to be comfortable but enough stiffness to feel premium.

The Showdown: Real-World Testing on the NPKC RO75 PRO

Theory is great, but practice is better. We took the NPKC RO75 PRO and ran an FR4 vs POM sound test (substituting PC for POM as they are acoustically similar) alongside Aluminum.

We used the exact same switches (pre-lubed linears) and keycaps (PBT cherry profile) for all three tests to ensure fairness.

Test 1: The Aluminum Stock Plate

The typing experience was crisp. The sound was distinct and sharp. However, on the spacebar and larger modifiers, there was a slight metallic resonance. If you enjoy a "clacky" build, this is your winner.

Test 2: The Polycarbonate (PC) Plate

The difference was immediate. The typing feel became significantly softer. The sound volume dropped, but the richness increased. The high-pitched ticking noise disappeared, replaced by a deep, marble-like sound. For this specific board, PC unlocked its full potential.

Test 3: The FR4 Plate

This was the surprise favorite for tactile switch lovers. It kept the typing sound lively without being piercing. It didn't "eat" the sound like PC, but it didn't amplify the highs like Aluminum.

Summary Comparison Table

Video: Hear the Difference

Words can only describe so much. Watch our quick sound comparison to hear how the NPKC RO75 PRO transforms with different plates.

Step-by-Step: Polycarbonate Plate Installation

Ready to make the switch? Polycarbonate plate installation requires a bit more care than metal plates because the material is soft and can scratch or bend if forced.

Plus, if you are getting deep into customization, you might want to check our guide on lubing switches to ensure your new plate sounds its best.

1. Disassemble the Case: Remove the keycaps and switches. Unscrew the case of your RO75 PRO to reveal the PCB/Plate assembly.
2. Separate PCB and Plate: Gently pull the old plate away from the PCB. Be careful with the stabilizer wires.
3. Install Stabilizers: If you are using PCB-mounted stabilizers (common on custom boards), ensure they are screwed in tight before placing the new plate.
4. Align the PC Plate: Place the Polycarbonate plate over the PCB. Note: Since PC is flexible, it might not sit perfectly flat until switches are inserted.
5. Insert Corner Switches: This is the pro tip. Insert switches in the four corners first. This aligns the flexible plate with the PCB holes.
6. Populate the Rest: Install the remaining switches. Support the hotswap socket from the back if possible to prevent popping a socket loose.

Matching Plates with Switches and Mods

A plate doesn't work in isolation. To get the best results, you need to think about the total package.

For example, if you are using "Frankenswitches" (custom hybrid switches), the plate choice becomes even more critical. A loud, long-pole switch like a BCP (Black Cherry Pie) might be too loud on Aluminum but perfect on FR4. You can read more about creating these custom switches in our Frankenswitch Guide 2025.

Pro Tip: If you use a PC plate, avoid over-tightening the case screws. PC plates rely on flex to sound good. Over-tightening creates tension points that kill resonance.

What the Community Says

We asked users of the NPKC RO75 PRO who swapped their plates to share their experiences. Here is what they had to say:

Frequently Asked Questions (FAQ)

Conclusion

Changing your keyboard plate is one of the most impactful modifications you can make. It changes the soul of the board.

If you want a sharp, precise typing experience, stick with Aluminum. If you want a balanced, poppy sound, go for FR4. But if you are chasing that deep, satisfying sound that defines the modern hobby, Polycarbonate is likely your endgame.

The beauty of the NPKC RO75 PRO is that you don't have to guess. Its easy-to-mod design invites you to experiment.

For more detailed guides on building keyboards, check out reliable resources like Tom's Hardware for general tech insights.