20 WATTS 3D PRINTED BLUETOOTH SPEAKER

Hello friends, Welcome to my very first Instructables publication. Here is a pair of potable bluetooth speakers that I made. These are both 20 watts powerful speakers with passive radiators. Both the speakers comes with a piezoelectric tweeter so that those high frequency notes can also be produced by the system. They have both horizontal and vertical placement configurations. Both the speakers share the same design but have differences in their inbuilt features. The first version has just Bluetooth audio input. The songs, volume, etc has to be controlled from your connected device like your smartphone. The second version has a ton of Inputs and controls builtin. It comes with bluetooth , USB, AUX and FM along with sound equalizer and 5 button controls. I decided to do it in red so that it could work as a matching stand for my headphones.

Both the versions of the speaker shares almost the same steps to build. The only difference is the audio decoder being used. A simple audio decoder is used in version one, whereas another decoder with multiple inputs is used in the second. And in this Instructable, I will be sharing the steps and circuits to both versions of the speakers.

COMPONENTS

1. 1.5inch 4 ohm 10W Full Range Speaker X 2
2. Piezo Tweeters X 1
3. Passive Radiator 85*40MM X 2
4. TPA3110 Power Amplifier Board 10+10 watts X 1
5. 3S Li-ion Battery Capacity Indicator X 1
6. 3S BMS X 1
7. DC-DC Step Down Power Supply Module 3A X 1
8. 18650 batteries X 3
9. 12 mm latching push button X 1
10. DC099 DC Power Jack X 1
11. 3.5mm Stereo Audio Jack Socket X 1
12. Telescopic antenna x 1
13. USB female socket x 1
14. Audio decoder for Version 1 (just Bluetooth) X 1
15. Audio decoder for Version 2 (Bluetooth, Aux,FM,USB) X 1
16. 7mm push button X 5
17. Carbon fiber sticker
18. M3 nuts and bolts

TOOLS

1. A pair of Scissors
2. Razor
3. Pliers
4. Hot-Glue
5. Screwdrivers
6. Sand Paper

The body of the speakers was 3D printed with bright red PLA. I have given enough clearance between the parts for an easy slide-in fit. There are just 3 parts to be 3D printed to make this speaker. Print all the parts in a vertical orientation for fewer supports and a better surface finish. The body of version 1 and version 2 is slightly different. So you will see two STL files for the body.

PRINT SETTINGS

• Nozzle size : 0.4mm
• Layer height : 0.2mm
• Nozzle temperature : 210°C
• Infill % : 40%
• Top and bottom thickness : 2mm
• Print bed temperature : 60C

These are optional steps you can do to make the speakers better looking.

1. Sand the surface of both the speaker faces using a fine sandpaper so that the carbon fiber sticker adheres properly when applied
2. Place the front panel and the speaker body face down on a sheet of carbon fiber sticker and draw a rough outline using a pencil and cut it out.
3. Peel the white cover off the sticker and apply it on both the faces. Make sure the whole face is covered
4. Cut off the excess sticker from the sides neatly using a pair of scissors.
5. Using a razor blade, cut out the openings for the speakers and passive radiators neatly and carefully. You can do this by slightly bending the razor to form a curve

This project used 3 speaker drivers. Two for bass and mid and the third which is a tweeter for covering the high-frequency notes.

Main drivers

1. Insert M3 , 12mm bolts through the holes for the speakers.
2. Insert the speaker driver onto the bolts
3. Fasten the speaker driver using 4 nuts with the help of a plier to hold the nut and a screwdriver to turn the bolts.

Piezoelectric Driver

1. Pull the speaker wires through the slot provided for it on the 3D printed part.
2. Press fit the driver into the cavity.
3. Apply a few layers of tape around the speaker if its a loose fit
4. In case you are worried if it will fall out, apply a little bit of glue before press-fitting.

Passive radiators are used to get huge bass out of a tiny speaker cabinet. They work only if the speaker cavity is airtight. The passive radiator reverberates with the pressure changes inside the speaker cavity, vibrating at certain frequencies producing bass.

1. Insert M3, 12mm bolts through the holes for the passive radiators on the speaker body.
2. Insert the passive radiators onto the bolts from the inside.
3. Fasten the passive radiator using 4 nuts with the help of a plier to hold the nut and a screwdriver to turn the bolts.
4. Apply hot glue all around the passive radiators to get an airtight fit.

The battery pack we are using here is a 3S lithium-ion 18650 battery pack. This is a 12.6-volt battery pack where 3 cells after connected in series.

First, the batteries are hot-glued together to form a kind of pyramid. Then the batteries are wired to the BMS as seen in the circuit diagram. Be very careful when handling these batteries.

Once the wiring is done, insert the battery pack into the speakers and position it in the middle, such a way that it won't touch the passive radiator even when the radiators vibrate. Use an instant adhesive like superglue or apply hot glue to hold the battery in place.

BATTERY CHARGING SETUP

1. Solder two wires to the DC female jack. Note which are the +ve and -ve wires.
2. Fasten the jack at the hole provided for it on left the sides of the speaker body with the help of pliers.
3. Apply hot glue all around the area where the jack is fastened to prevent airflow.
4. Solder the Positive and Negative wires to P+ and P- of the BMS respectively
5. The battery has to be plugged to a 12.6-volt charger to activate the BMS for the first time.

So this is the circuit for the speaker version 1 which has just Bluetooth as audio input.

I made this circuit diagram in windows paint software. I saw another Instructables publisher using the same method to display his speaker circuit so I did as well.

Here I have scavenged the Bluetooth receiver part which was still working from an old busted Bluetooth amplifier.

But you guys can use another equivalent Bluetooth receiver as shown in the circuit diagram. I have attached the link to buy this receiver on the supplies list.

The buck convert output voltage is set to 5v by turning the built-in potentiometer. Connect the load only after this is done.

Stick the amplifier board using double-sided tape on the free area right side of the battery pack and the Bluetooth receiver on the left side. Use hot glue as well to hold the boards in place.

And finally, fasten the power button onto the speaker body.

This is the circuit diagram for speaker version 2 which supports Bluetooth, FM, USB, AUX etc.

First, the USB socket has to be extended so that it reaches the outer casing of the speaker. This can be done by soldering 4 wires to the builtin socket's soldering point and soldering a separate socket to the other end of this wire. Use instant glue to stick the new socket in the cavity provided for it in the speaker body.

similarly, extend the built-in push buttons using wires and separate push buttons.

Fasten the auxiliary port on the speaker body. Attach the antenna using any hardening epoxy like Mseal.

The battery indicator is directly soldered to the power output of the battery BMS.

Connect the antenna on the soldering terminal marked "ANT" on the Audio decoder board.

Once all the wiring and fastening of the components are done, use glue (I used fevicol all fix) to make all the tiny gaps between the fastened components and the speaker body airtight.

The final step of the build is closing the speaker. I used fevicol all fix for this. Pour the glue carefully along the edge of the speaker body and insert the face panel. Use cable ties to hold both the pieces together while the glue dries. The excess glue that oozes out has to be wiped off using a cloth. Wait for 24 hours for the glue to dry completely.

Also, attach rubber feets using the same glue. The feet will prevent the speakers from slipping off the table or move around because of the vibrations.

Many people prefer to place speakers in a vertical position, especially when the speaker has to placed at a cramped location. So I decided to add a stand which allows user to place the speakers vertically.

A leather padding is glued to the bottom of the stand to prevent any slippage.

And that's the final step. Thank you for going through my Instructables. ENJOY BUILDING