Hello everyone, How's it going?

So here's something loud: a Bluetooth speaker made from scratch by reusing the body from an old project and speakers from an old home theater system.

The goal here was to create a working speaker from reusing stuff, so I printed a top and bottom cover that hold the left-right speakers and subwoofer.

I previously made a project that had a middle body portion made completely from PLA, it took more than 20 hours to print and was super huge.

After a few changes I made to that project, the middle portion was swapped out with another part, and the big 250mm x 270mm part became junk or an extra piece of plastic.

To reuse this part, I planned to make a Bluetooth speaker from it by using two additional 3D-printed parts that will hold the speakers and audio board; the middle part will act as a base and will look similar to a boom box or a box speaker.

It even has a handle for carrying it around. We can use speakers for outdoor get-togethers or for small parties.

This article is about the whole building process for this speaker, so let's get started.

Material Required

Following are the materials used in this built-

• ZK-TB21 Audio Power Amplifier Module
• 4 Ohms Speakers x 2
• 2 Ohms Subwoofer x 1
• 3D Printed Parts
• DC Barrel jack
• 3mm LED
• Diode SR206

Audio Module

For the audio control board, I'm using the ZK-TB21, which is a 2.1-channel audio power amplifier based around the TPA3116D2 power AMP chip.

TPA3116D2 is a Class D stereo amplifier that can drive speakers up to 100 watts; driving two 100-watt speakers, the ZK-TB21 utilizes two of these TPA3116D2 chips. one for the left and right speakers, and one for the subwoofer

Because it's a power amp, things get super hot, so there's a heatsink on the TPA chips for the dissipation of heat.

Also, there's a Bluetooth audio IC on this board, which lets us connect with this board for audio streaming.

Technical Specs of Module-

• Product name: 2.1 channel Bluetooth audio power amplifier module
• Product model: ZK-TB21
• Bluetooth version: 5.0 (unobstructed, 10 meters)
• Input sensitivity: 500mV
• Input method: AUX + Bluetooth
• Number of channels: 2.1 channels
• Power amplifier chip: TPA3116D2 (with AM interference suppression function)
• Adaptable power supply: DC12~24V / 5A or more (over-voltage, output power setting)
• Adapt to speakers: 20~100 W, 4~8.
• Output power: 50W for left and right channels
• Subwoofer 100W
• Protection mechanism: overvoltage, undervoltage, overvoltage, DC detection, short circuit protection
• Product size: 120mm * 100mm * 20mm
• Product weight: about 256g (including packaging)

PCBWAY Giftshop

As for sourcing the audio module, I used PCBWAY's Giftshop for ordering the sensor.

https://www.pcbway.com/project/gifts_detail/2_1_channel_Bluetooth_audio_power_amplifier_module.html

PCBWAY also has a dedicated components store in addition to PCB Services.

PCBWAY GIFTSHOP is an online marketplace from where we can source all the major electronics stuff, like Arduino boards, Raspberry Pi boards, Modules, sensors, etc.

PCBWAY has this system that lets us purchase anything from their gift shop with beans, Beans are like redeemable currency or coupons that we get by placing an order on PCBWAY or by sharing your projects in the community to get beans.

Check PCBWAY out for getting great PCB service from here- https://www.pcbway.com/

Speakers

Both the speakers and subwoofer have been salvaged from an old Samsung home theater system that I had; it was from 2010 and was a banger at that time.

The speakers were in great condition, and even the amplifier board was working, the only problem was that it was dated and didn't even have Bluetooth. Also, nobody uses Blueray anymore, so it was time to salvage stuff from it for a modern build.

Wiring Connection

Above is the wiring connection for this project, and it's a simple one.

We connect the positive and negative terminals of the Left-Right Speaker to the ZK-TB21's Left and Right speaker connectors.

Subwoofer positives and negatives go into the subwoofer connector of the ZK-TB21 Module.

Battery VCC and GND will be added to the board's Battery CON.

For charging the battery, we add a DC jack, and its VCC is connected with an SR206 diode in series with the battery positive.

On the input side, there is also an indication LED in series with a resistor to show that the charger is plugged in.

3D Printed Parts

As for the 3D-printed parts required in this build, I have reused the middle base part from a previous project.

I took the Cad file of the previous project and removed everything from it except for the middle part and handle with four holders that are keeping the middle body in its shape.

This middle body is divided into two halves, and four holders are used to mount both halves together.

I modeled the front and back portions for the middle base and added left-right speakers to the front and a subwoofer to the backside.

After completing the design, I exported the 3MF files and printed them on my Ender 3 with red PLA and a 0.4mm nozzle.

Front Assembly-Left & Right Speakers

• We first start the assembly of the Front part, we add Both Left and right speakers in their place by using two M3 Mounting nuts and bolts.
• Next, we add Audio Module to its place by putting the pots in the holes on the body and tightening their locking nut to hold the board in its place.
• after adding the audio module, we add wires to the positive and negative of both speakers by using a soldering iron.
• Next, we add wires to the audio module in the right order by following the wiring diagram.

Back Assembly- Subwoofer

• Next, we start with the back panel assembly, which holds the subwoofer in its place.
• We use four M3 Nuts and bolts to hold the subwoofer.
• Next, we place the DC Barrel jack and add Diode, leds, and wire to it which we can later attach to the Main Amp board.
• We all add wires to the subwoofer's negative and positive terminals.

Combining the Front and Middle parts together

Next, we add the front part to the middle body by first mounting it on one side of the middle body and then adding screws inside the middle part and from the outside.

Adding Battery Pack

Next, we add a 12V 5.2Ah Battery Pack inside the speaker body by first adding the ZK-TB21 Battery Connector (which was in the box) to the Positive and negative of the Battery Pack, we can now plug the battery on the audio amp board.

Adding the Back Part with the main body

• Next, we place the Back part which contains the subwoofer, on the Main Body but before doing that, we connect the subwoofer Wires to the subwoofer port on the audio module along with charging IN wires directly to the battery's positive and negative ports.
• after this, we use screws to permanently hold the back side with the middle body, Bluetooth speaker is now completed.

Finishing Touches

To make this setup look pretty, we add potentiometer knobs to all five pots.

Result

Here's the final result: a huge Bluetooth speaker made by merging discarded 3D-printed parts with new ones. The audio amplifier is working properly as well; just watch the attached video for the results.

As for Turning this setup ON, there's a rotating ON-OFF switch in the volume potentiometer which acts as a main ON-OFF switch for the whole unit.

This is it for today guys, thanks PCBWAY for supporting this project, check out PCBWAY for getting great PCB service along with other services like 3D printing services for very less cost.

Thanks for reading this article, and I will be back with a new project soon.

Peace.