Quick 3D Printed Mini HiFi Speaker

Hello everyone,

A while back I made an Instructable about my larger 3D printed omni-directional speaker and while I absolutely love it the design prevents me from being able to throw it in a bag and carrying it with me.

So I decided to design a new one that was smaller, quick to print and a lot more rugged.

This new design features only a single high quality speaker with two passive radiators and is battery powered with a 10m+ bluetooth range.

Join me as I make my new favourite travel companion...

To replicate this Instructable you will need the following:

- 3in Full range speaker driver

This is the most important component in the build as your final result will depend on the speaker driver used. I'm using a salvaged aluminium cone Bose driver.

You might need to alter the design to fit your driver.

Good 3 inch speaker but will need some minor modifications to the enclosure

or

If I was to redo this Instructable I would replace the 3inch speaker with two of these 1.5inch drivers

- 5W Bluetooth MH-M38 Amplifier

Amplifier

- Lipo/18650 Battery

18650

- TP4056 Lithium charger

TP4056

- 4A 3.7V Battery BMS

BMS

- TTP223 Touch sensor ( THIS CAN BE REPLACED BY ANOTHER ON/OFF SWITCH )

TTP223

- ^ Mosfet/relay ^

In this Instructable I used a transistor mounted directly to the TTP223 but I would recommend using a ready made module

Mosfet module

- 2x 50mm x 90mm Passive radiator

50mmX90mm Passive radiator

- Access to a 3D printer

- CA Glue

- High filler primer

- Sanding paper

- Spray paint

- Polyurethane sealant

- Soldering iron & solder

With this new speaker I used Fusion 360 to create an enclosure that had as few as possible parts to print with no wasted filament.

The entire speaker consists of only two printed parts, the main enclosure and the bottom lid. It might not be the most intricate design but I wanted to make it as compact as possible and more importantly it needs absolutely no supports to print. In the end I liked how "industrial" it turned out.

With my settings the main body took under 4 hours to print (at only 30mm/s) using only 22M of filament and the lid took one and a half hours to print using 15M of filament.

The maximum size is 160mm so most 3D printers should be able to print all the necessary parts.

My settings:

Main enclosure

Material: PLA+

Speed: 30mm/s

Temp: 215 deg C

Nozzle: 0.8mm

Bottom lid

Material: TPU

Speed: 30mm/s

Temp: 215 deg C

Nozzle: 0.8mm

I decided to print the bottom lid in TPU to reduce vibration and it is more durable for a base but both parts can be printed in PLA/ABS/PETG just make sure to stick some rubber feet on the bottom.

Files:

I have included the .stl files and also the fusion 360 files so that you can edit it to suit your needs.

After your enclosure has finished printing it's time to put in some elbow grease...

First I like to take a coarse grit sanding paper like 180 to 220 grit and with a sanding block (this amazing little sanding block that I used can be found on Thingiverse) and get rid of most of the imperfections. PLA and PETG can be a little difficult to sand so I sometimes use very coarse 80 grit paper to get rid of imperfections and then just go over it again with 220 grit.

After you've removed most of the blemishes with the 220 grit paper you want to spray your parts with some plastic primer, do this in thin coats and wait for each coat to dry completely.

TIP: Spray a very light coat of matt black paint over your primer before sanding, this will highlight any imperfections as you are busy sanding.

Wait for your primer to dry completely and then it's time to get sanding again...

Sand the primer with water and some 400 grit paper to get rid of as many imperfections as possible, you will also want to use a sanding block for most of the primer sanding otherwise you wont get nice clean edges.

When you are happy with the look of your primed and sanded parts you can go ahead and give them a few coats in the colour of your choice, I chose a classic satin black for mine.

Spray your parts by following the instructions included by the paint manufacturer.

We start by preparing our battery, for safety and to make sure the there is not a bottle neck at the charging boards protection I added a separate 4 amp BMS to the battery so that I use the TP4056 board only for charging.

Following the schematic:

Starting at the TP4056 board we solder wires onto the B+ and B- points on the board, I will not be using the P+ and P- as i'm using the external BMS. If you will be using a lower powered amplifier like a PAM8403 you can use the TP4056's onboard BMS that is rated for 1-2amp and omit the 4amp BMS from the build.

Pay careful attention to the silkscreen that's on the boards that you are using as it may differ from the ones I used.

The wires coming from the TP4056 now gets soldered directly onto your 18650 battery, B+ from the board goes to the top (vented side) cap and the B- goes to the bottom flat side of the battery. If you are unsure of the polarity of the battery you are using please search the model number online first to make sure before soldering. ( I used a lipo battery but I suggest you use a 18650 battery as it has more capacity and readily available )

Lithium battery safety:

"Hazards Lithium batteries are generally safe and unlikely to fail, but only so long as there are no defects and the batteries are not damaged. When lithium batteries fail to operate safely or are damaged, they may present a fire and/or explosion hazard. Damage from improper use, storage, or charging may also cause lithium batteries to fail. Testing batteries, chargers, and associated equipment in accordance with an appropriate test standard (e.g., UL 2054). NRTL certification (where applicable), and product recalls, help identify defects in design, manufacturing, and material quality. Damage to lithium batteries can occur immediately or over a period of time, from physical impact, exposure to certain temperatures, and/or improper charging. Physical impacts that can damage lithium batteries include dropping, crushing, and puncturing. Damage to all types of lithium batteries can occur when temperatures are too high (e.g., above 130°F). External heat sources (e.g., open flames, heaters, etc.) can also accelerate failure in cells with defects or damage from other causes. Damage to lithium-ion batteries can occur when the batteries themselves or the environment around the batteries is below freezing (32°F) during charging. Charging in temperatures below freezing can lead to permanent metallic lithium buildup (i.e., plating) on the anode, increasing the risk for failure. Charging a device or battery without following manufacturer’s instructions may cause damage to rechargeable lithium-ion batteries. For example, some manufacturer-authorized chargers will cycle the power to the battery on and off before it is fully charged to avoid overcharging. Since ultra-fast chargers may not cycle power, do not use them unless the manufacturer’s instructions include them as an option. Heat released during cell failure can damage nearby cells, releasing more heat in a chain reaction known as a thermal runaway. The high energy density in lithium batteries makes them more susceptible to these reactions. Depending on the battery chemistry, size, design, component types, and amount of energy stored in the lithium cell, lithium cell failures can result in chemical and/or combustion reactions, which can also result in heat releases and/or over-pressurization. In chemical reactions, by-products from the electrolyte solution and electrodes can increase the pressure in the cell to the point where the cell walls expand and by-products leak out. Chemical by-products usually include carbon monoxide, carbon dioxide, hydrogen, and hydrocarbons. In many cases, the by-products are also combustible and could ignite. In combustion reactions, a thermal runaway releases byproducts that may ignite to cause smoke, heat, fire, and/or explosion. The by-products from a lithium battery combustion reaction are usually carbon dioxide and water vapor. In some lithium batteries, combustion can separate fluorine from lithium salts in the battery. If mixed with water vapors, fluorine may produce hydrofluoric acid, which is particularly hazardous because workers may not feel its effects until hours after skin exposure. Prevention Workplace injuries from lithium battery defects or damage are preventable and the following guidelines will assist in incorporating lithium battery safety into an employer’s Safety and Health Program: Ensure lithium batteries, chargers, and associated equipment are tested in accordance with an appropriate test standard (e.g., UL 2054) and, where applicable, and certified by a Nationally Recognized Testing Laboratory (NRTL), and are rated for their intended uses. Follow manufacturer’s instructions for storage, use, charging, and maintenance. When replacing batteries and chargers for an electronic device, ensure they are specifically designed and approved for use with the device and they are purchased from the device’s manufacturer or a manufacturer authorized reseller. Remove lithium-powered devices and batteries from the charger once they are fully charged. Store lithium batteries and devices in dry, cool locations. Avoid damaging lithium batteries and devices. Inspect them for signs of damage, such as bulging/cracking, hissing, leaking, rising temperature, and smoking before use, especially if they are wearable. Immediately remove a device or battery from service and place it in an area away from flammable materials if any of these signs are present. If batteries are damaged, remove them from service, place in fire resistant container (e.g., metal drum) with sand or other extinguishing agent and dispose in accordance with local, state, and federal regulations. Contact a local battery recycling center for disposal instructions. Follow manufacturer’s guidance on how to extinguish small battery fires, which could include using ABC dry chemical extinguishers, Class D fire extinguishers (for lithium-metal), dirt, or sand."

After soldering the charging module to the battery we need to solder in the BMS to protect the cell from over charging/discharging and shorts. To do this we solder a wire from the positive of the battery to the B+ of the BMS board and then a wire from the negative of the battery to the B- on the board.

Next you can solder on a wire to the P+ (this will be the V+ 5V going to the remaining circuit) and a wire to the P- (this will be the circuit ground) of the board.

To turn the speaker on I decided to use a TTP223 touch sensor, 5v and ground are connected to the module and when it is touched it outputs a 5v signal on the OUT pin that can be connected to the gate of a mosfet to turn the amplifier on.

For the module to be used as a locking switch jumper B on the board has to be soldered.

Here is a Instructable by mybotic on how to use a TTP223 sensor: TTP223

^ This can also be replaced by a simple on/off switch ^

I've included a link to a great little easy to use mosfet board that I would use instead with the TTP223.

From the power switch we now need to solder the MH-M38 amplifier. Solder your power from the switch to the VBAT and GND. Optionally you can mount a ~1000uf 10-16v capacitor at these solder points to help keep the voltage stable.

Lastly you just need to solder on your speaker to the output of the amplifier and your done.

With the enclosure painted we can start assembling the internals.

Using polyurethane sealer run a bead around the ring that the speaker fits into and press your speaker into the enclosure, be careful not to add too much sealer as it could squeeze out the front of the enclosure and will be difficult to remove.

Now using CA glue apply a thin coat on the shoulder of the two passive radiators and place them into their cavities, spray some activator on the inside of the enclosure ( sometimes the activator can leave marks on the paint so it's better to spray on the inside ) to set the glue.

We can now use the same CA glue to stick the switch on the inside wall of the enclosure, placement will depend on where you want the on/off touch location on the outside to be.

Add a layer of polyfill/stuffing loosely in the enclosure and then run a bead of sealer around the edge of the enclosure, now press the bottom lid into place and wipe away any excess sealer with a cloth and some alcohol.

Leave for 24 hours to allow the polyurethane sealer to fully cure.

Now that your speaker is assembled it's time to test it out!

First you will need to charge it, this is important even if your battery isn't empty as plugging it in will activate your battery protection board.

Plug in the micro USB and wait untill your LED switches from red to blue indicating an full charge.

After charging touch the switch area ( or use turn on the switch if you've used a normal switch ) and it should turn on with the Bluetooth modules chime, look for the available Bluetooth devices on your phone/computer in this case it should be MH-M38 if you're using the same amplifier and connect.

Play a song with a heavy bass line to check if there are any air leaks that need to be sealed.

Now all that's left is to sit back and enjoy your new creation.

Please share your builds with me and let me know if there's anything you'd like to see next.

Happy making!

If you need any help with a step or need the design altered feel free to leave a comment below.