Introduction: Portable Bluetooth Speaker With Built-In PowerBank
Runner Up in the
Audio Contest 2017
A powerful, long lasting wooden Bluetooth Speaker, this is my attempt at a homemade Bluetooth Speaker with "BASIC TOOLS" and "SCRAPPED MATERIALS"
I'm going to show you how I built this super simple 10 watt bluetooth speaker and I'm happy to say that it's now as simple, affordable, good looking and good sounding as it can possibly be! This speaker is based on MDF fiberboard which is reclaimed from an old Cabinet Box, two 50mm full range speaker drivers which are also reclaimed and a single passive radiator, all wrapped in Carbon Vinly.
The only reasons to design and build our own speakers are:
- because we wish to prove to ourselves that we can
- we wish to stretch our intellects in the design process we wish to stretch our woodworking skills in the process.
- we wish to irritate and annoy our loved ones while spending hours in the garage or basement with noisy power tools.
- lack of loved ones to cuddle in the long Winter evenings. ( just kidding ;) ).
- we can not find any manufacturer who makes exactly the combination of attributes that you desire.
- 5W output per Channel
- Bluetooth 4.0
- Micro USB Charging
- Built in Powerbank
- 8 hour battery life
- Dual 50mm drivers, single passive radiator design
Step 1: Selecting Box Material
I'm using Scrapped MDF fiberboard for the ease use and it is desired mainly for speaker enclosures.
Enclosre type The best wood isn't quite wood! A speaker cabinet needs to be as non-resonant as possible. Generally, that means either dense plywood (birch ply is good) or MDF fiberboard. 3/4" thickness is standard. 1" if you're a perfectionist (and aren't worried about a hernia!). Internal bracing is often a good idea too. Actual wood will resonate and add sonic coloration to the sound in unpredictable and usually undesirable ways.
For appearance, a hardwood veneer is usually applied. Or you can use thinner MDF/ply substrate with a thicker hardwood overlay; for instance, half-inch MDF glued with quarter inch hardwood facing. You can also use laminates or paint to good effect. Skillfully applied lacquers or automotive finishes can look great!
Advantages of using MDF fireboard.
- MDF is generally cheaper than plywood.
- The surface of MDF is very smooth which makes it great surface for painting.
- MDF is very consistent throughout, so cut edges appear smooth and won’t have voids or splinters.
- Because of the smooth edges, you can use a router to create decorative edges.
- The consistency and smoothness of MDF allows for easy cutting of detailed designs (such as scrolled or scalloped designs) using a scroll saw, band saw or jigsaw.
Step 2: Parts and Tool List:
- 50mm speaker driver unit (1 pair) [Scrapped]
- Rugged Passive Radiator [Scrapped]
- MDF fiberwood (10mm & 5mm thick) [Scrapped]
- Wood Glue
- Bluetooth module [Scraped]
- PAM8406 Class D Audio Amplifier Board
- Powerbank Power Circuit [Scrapped]
- Li-Po battery ( 4000mAh)
- 3300uf 10v Capacitor
- Heat shrink tube
- Carbon Vinyl
Most parts are Reclaimed or Recycled from old products which were laying around.
- Hand Saw
- Drill Machine
- Hot Glue Gun
- Sanding Paper ( different grits)
- Wire stipper
- Detail Knife
- Sanding file
All are Basic Tools
Step 3: Plans and Designing the Speaker Box:
There is no more basic wood joinery than the butt joint. A butt joint is nothing more than when one piece of wood butts into another (most often at a right angle, or square to the other board) and is fastened using mechanical fasteners.
Designing the Sealed / Closed enclosure with bass reflex passive Radiator.
A sealed enclosure is exactly what it sounds like. A box, of whatever shape you wish, that is air tight. When the speaker moves, the air does not escape the box, it only alters the pressure inside it. This is the easiest enclosure to design and build. You only need to calculate the internal volume of the box, which is done with little effort. Stuffing the box with sound dampening material will help absorb stationary waves produced by the back of the speaker and yield better results.
- If space is an issue, sealed enclosures are the smallest.
- Easy to design.
- Easy to build.
- Design errors don’t have big impact on overall sound.
- High power handling.
- Great transient response (plays with little effort short duration sudden sound waves, like drums).
Outer dimension of the box :
- height 80 mm
- wide 200 mm
- depth 65 mm
- thickens of the wood 12 mm
Speaker Driver Holes:
- 50mm diameter (2X)
- According to Rugged Passive Radiator (size mentioned in picture)
Step 4: The Face and the Back
After marking the front and back according to the measurements, I used a hand saw for cutting the straight paths.
For the circle, I drilled the hole out and stand it smooth using file. Same goes for the passive radiator. And smoothing all the surface using sand papers.
Step 5: Building the Enclosure
Using wood glue I've joint the bottom and top section onto the front section. clamp it up and let it dry.
Step 6: The Electronics
Power Bank Charger Board and Power Supply Step Up Boost Module for Li-Po Battery DIY
I have recycled this circuit from an old power bank.
By pressing power button this circuit ONs when detects any load on the output. And automatically OFFs when the load is removed within 10 seconds. The marked (B+) and (B-) are the points where the battery connects. (Out+) and (Out-) are the output +5v and GND which are also directly connected to the USB pin onboard.
I had scrapped the bluetooth module from an old bluetooth headset.
Alternate bluetooth module.
Bluetooth Stereo Audio Receiver Dongle it an good and cheap alternate bluetooth for this project.
PAM8406 class D audio amplifier.
- Features Dual channel stereo output 5w + 5w power.
- Works with 2.5V-5v power supply. High amplification efficiency 85%.
- can directly drive 4 Ω/8 Ω small speakers. Good sound quality & noise suppression Unique without LC filter class D digital power board.
- Can use computer USB power supply directly.
Connect the the +5v point of the amplifier to the output +5v of the charging circuit and Audio IN point to the audio output of the bluetooth module. Adding 3300uf 10v Capacitor in parallel with +5v and GND.
Step 7: Mounting the Speaker Driver and Passive Radiator and Electronic:
Here, for mounting of the speaker drivers I've first aligned the drivers, marked the holes for the screw and drilled the hole using 1.5mm drill bit, making sure the hole doesn't go any deeper.
After that using Hot Glue seal the drivers, so no air can pass through the gap.
And for attaching the Passive Radiator I've use wood glue, so it sticks for longer against the excursion and vibration - using hot glue will be bad idea.
Everything should be sealed properly.
Step 8: Sealing the Box
After all the inside job like electronic mounting, wiring and joining the points well using heat shrink tubes. I sealed the box air-tight using wood glue and let it dry properly using clamps.
I've checked everything twice before sealing the box so no problem occurs afterwards
The box is sealed all air-tight.
Step 9: Sanding and Finishes
Now that our enclosure is dry, its time to clean it up! We will start off by thoroughly sanding down the whole enclosure. We want our sides to be completely flush. Before we continue, we will sand the whole enclosure in very fine sand paper.
Step 10: The Finishing Bits
After sanding, it's time to add a finish. If you would like to paint or draw patterns on to your enclosure or vinyl it now is the time! I decided use Black Carbon Vinyl to wrap it up.
Working with Vinyl Wraps needs patience and little skills, but it is the easiest and cheapest way to make it look near perfect.
At last attach rubber feet at the bottom of the speaker box.
Step 11: The Finished Product!
Let me know how it looks!!
Step 12: The Sound Test!
Step 13: Remarks and Further Improvement
- Lack of command buttons
- The battery Backup
- A good Quality Amplifier Board
If you have any Problem related to this project, please let me know.
Thank You !!
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Please be positive and constructive.