3D Printed Soundbar

Hi, I’m Kishan, a Class 12th student preparing for my board exams in February 2026. Between late-night study sessions and endless revisions, I often found myself overwhelmed by stress. So, I decided to turn that energy into something creative — something that could literally make me feel better.

That’s how Ampfinity was born — a custom-designed Bluetooth speaker that transforms silence into powerful sound and stress into satisfaction.

I built it using a pair of old Sony TV speakers, driven by the ZK-MT21 amplifier board and a Kripower high-quality SMPS for strong, distortion-free performance. Every beat feels clean, every note powerful. The body was entirely designed in Autodesk Fusion 360, where I carefully modeled every curve, vent, and grill hole to achieve both beauty and balanced acoustics.

Ampfinity isn’t just a speaker — it’s a reminder that even during exam pressure, we can create something that brings us joy, motivation, and rhythm. It’s my personal make some noise machine — built from recycled parts, designed with passion, and engineered for infinite sound.

Components

1. ZK-MT21 Amplifier
2. 3 Pin AC Socket
3. 3 Pin AC Cord
4. XT90 Connecter
5. 10w 8Ω Spekar
6. 24v 5a SMPS

Tools

1. Soldering Iron
2. Screwdriver

To begin this project, I designed the Ampfinity in Autodesk Fusion 360, carefully keeping all the component dimensions and aesthetics in mind. My goal was to make it small, futuristic, and easy to assemble, just like a comercial one.

The design features a clean body. It’s also 3D-printing friendly, requiring no complex supports or post-processing. You can easily view or edit the CAD model using the Fusion 360 web viewer, and feel free to customize the design to match your own style or components.

For 3D Printing, You can directly download the required STL files below:

1. 1x Body.stl
2. 1x Back LID.stl
3. 1x Grill.stl

I started by placing both Sony TV speakers into the 3D-printed enclosure. The cutouts were perfectly sized, so the speakers fit tightly without any gaps. I fixed them in place using small screws and added a thin layer of foam tape behind each one to reduce vibration and improve sound quality. Once both speakers were firmly mounted, the front side of Ampfinity began to take its real shape.

To prepare the ZK-MT21 amplifier for installation, I first opened its metal cover by removing all the screws and standoffs. After that, I carefully took off the potentiometer caps and unscrewed the nuts from each potentiometer. This step helps in mounting the amplifier board neatly inside the enclosure later without any extra height or obstruction.

After modification, I placed the ZK-MT21 amplifier board into its dedicated slot inside the enclosure. Once it was aligned properly, I secured it using the original nuts and screws, tightening them gently with a plier to keep the board firm and stable. Finally, I reattached the potentiometer caps on top to complete the look and make the controls ready for use.

Now it’s time to connect the speakers to the amplifier. The left speaker is connected to the L+ and L- terminals, and the right speaker is connected to the R+ and R- terminals of the ZK-MT21 amplifier board. Make sure the wires are firmly fixed in the terminal blocks to avoid any loose connections or noise issues.

On the back lid of the enclosure, I placed the AC socket in its designated slot. Once it was aligned properly, I secured it firmly using two small screws. This socket will be used to connect the power supply safely to the amplifier system.

On the back lid of the enclosure, I placed the XT90 connector in its dedicated slot, just like the AC socket. After aligning it properly, I secured it tightly using two screws. This connector is added as a backup power option — it allows Ampfinity to run on a battery when electricity is not available.

The SPDT switch was placed carefully in its slot on the back lid. I fixed it securely using super glue to keep it stable in place. This switch is used to turn the Ampfinity ON and OFF, making it the main control for powering the speaker system.

In this step, I made all the power connections inside the enclosure. The XT90 connector and the AC socket were connected using thick 18 AWG wires to handle high current safely.

One wire from the AC socket was passed through the SPDT switch, which allows me to turn the Ampfinity ON or OFF easily. All solder joints were carefully insulated using heat shrink tubing to prevent short circuits and give a clean, professional finish.

For power, I used a Kripower 24V 5A SMPS. Since the space inside the enclosure is limited, I first opened all the screws and removed the metal casing — keeping only the main SMPS board.

Additionally, I made one more small modification. I removed both MOSFETs from the board, extended their leads using 24 AWG wires, and covered them with high-quality heat shrink. This not only helps in better fitting the board but also improves cooling and flexibility during placement inside the case.

⚠️ Note: Always ensure the SMPS is disconnected from power before opening it, and handle the circuit carefully to avoid electric shock.

Now connect the AC socket wires to the phase and neutral terminals of the SMPS input. Make sure the connections are tight and secure to avoid any loose contact.

Next, connect the XT90 connector to the output terminals of the SMPS, followed by the DC 5525 jack using suitable wires. Make sure all connections are firm and insulated properly with heat shrink for safety.

The fun part is — when you power the system through the AC socket, the XT90 connector also provides a 24 V output. This means you can easily use the same port to power other devices or charge a battery when AC is available.

Before closing the enclosure, connect the DC 5525 jack to the amplifier’s power input. Once all connections are secured, carefully place the back lid onto the main body and fasten it using screws. Make sure everything fits neatly and no wires are pinched.

Take the grill and carefully place it over the speaker section on the front panel. Align the screw holes properly, then tighten it using small screws. This grill not only gives a clean and professional look but also protects the speakers from dust and damage while keeping the sound clear and open.

Now it’s time to bring Ampfinity to life! Plug the 3-pin AC cord into the socket and connect it to a 220V AC supply. Turn the main switch ON, then gently rotate the first potentiometer until the power indicator lights up.

Once the amplifier powers on, connect your device via Bluetooth, play your favorite track, and enjoy the rich, clear sound from your custom-built Ampfinity speaker!

Building Ampfinity was not just about creating a powerful Bluetooth speaker — it was about turning stress into creativity and sound into happiness. As a Class 12th Student, I often felt the pressure of studies. Music became my escape, and that’s what inspired me to build this project — something that could lift my mood and fill my surroundings with energy.

Ampfinity isn’t just a speaker — it’s a reminder that even during stressful times, a little creativity and noise can make life sound beautiful!