Thank you for checking out this portable Bluetooth + WiFi speaker build I have come up with. As always I will have the laser-cut plans, the wiring diagram and the whole parts and tools list in the steps below. Make sure you check my YouTube video first and then come back for more details. Let's get started!
Step 1: Plans
For this build it is necessary to get the plywood panels laser cut. Since I do not own a laser-cutter myself, I outsourced a few people from a local company that were able to laser cut the plywood pieces out for me. You can find the Laser Cut Plans below. It is possible that the scale of the drawing might be messed up, so just for reference - the diameter of the hole next to the Bluetooth and WiFi logo on the back panel is supposed to be 1.8 millimeters. Those holes are for the LEDs. You should receive 5 different plywood panels - two front panels, two back panels and the enclosure template. Also, there is a plywood disc included in the plans which you should take care not to lose. It is for the volume control potentiometer. Same goes for a circle cutout near the battery logo - it will be used as a button.
Since the tweeters that I used are no longer for sale, I updated the plans for the speaker accordingly.
I have also included the wiring diagram which you can download or print but make sure you zoom in for a better and clearer view. Let's start the build!
Step 2: Parts and Tools
For this speaker I decided to try implementing not only Bluetooth 4.0 but also a WiFi module. Here I am using the Up2Stream WiFi module which is super easy to use and delivers great sound quality at a reasonable price. There is also an Aux input which when plugged in automatically disables the Bluetooth or WiFi input letting us make a simpler and cleaner looking speaker with less buttons and switches which is always pleasing to get rid of.
The speaker is powered by three Lithium Ion 18650 cells connected in series, resulting in 12.6 Volts total and a capacity of around 3Ah. The cells are being monitored by a Battery Management System (BMS) which I will show in depth of how to connect it to the cells. After testing I can confirm that these cells are able to provide the necessary power for around 6-8 hours depending on the volume.
For the amplifier I chose one of my favorite Class D amplifiers - the Yamaha YDA138-E. It delivers plenty of power in to the drivers with plenty of bass and clear highs. One of the best features of this amplifier is that there is absolutely no audible noise being projected when the speaker is not playing. I have tried many Class D amplifier and I can truly say that this one is top of the range in it's price point.
For the Bluetooth module I chose the KRC-86B Bluetooth 4.0 audio receiver. Nowadays there are many boards superior to this one but it still performs great, delivers unobstructed sound and connects instantly to the streaming device.
- Up2Stream WiFi Module - https://bit.ly/2Nac7sv
- YDA138-E Amplifier - https://ebay.to/2TAl40G
- Bluetooth V4.0 Module - https://ebay.to/2JieAk9
- 6 Ohm Woofers - https://ebay.to/2TdVrCF
- 6 Ohm Tweeters - https://ebay.to/2sZoNcF
- 75mm Passive Radiator (3 pcs) - https://ebay.to/2RmjE7T
- 2 Way Crossovers (2 pcs) - https://ebay.to/2TiOsIP
- 19mm Led Switch - https://ebay.to/32dnmYm
- 18650 Cells (3 pcs) - https://ebay.to/2LGhzVq
- 3S LED Battery Indicator - https://ebay.to/2RkkcLO
- 3S BMS - https://ebay.to/2DENnFB
- 12.6V Battery Charger - https://ebay.to/2D6jXAm
- Kapton Tape - https://ebay.to/2sQBvu3
- Step Down Converter - https://ebay.to/2RTwK0Z
- Isolated Converter - https://ebay.to/2TTBhxE
- Ground Loop Isolator - https://ebay.to/2MAA1Nv
- 2 Position Slide Switch - https://ebay.to/2Tl4D8k
- Tactile Button - https://ebay.to/2CMs3MN
- DC Input Jack - https://ebay.to/2JcP6Ss
- Stereo Audio Jack - https://ebay.to/2Rj7m05
- Audio Input Cable - https://ebay.to/2HNwtFf
- 1k Ohm Resistor - https://ebay.to/2WoMfgC
- Blue 2mm LED - https://ebay.to/2FPRi4I
- Green 2mm LED - https://ebay.to/2CUdpD8
- Red 2mm LED - https://ebay.to/2WpLQuz
- Amplifier knob - https://ebay.to/2G3d3gW
- M2.3 x 12mm Screws - https://ebay.to/2RDrUFG
- M3x8mm Bolts - https://ebay.to/2G5SZdR
- M3 Hex Nuts - https://ebay.to/2G53zBE
- Adhesive Foam Strip - https://ebay.to/2SXcpFf
- Brass Standoffs - https://ebay.to/2sSpgNs
- Rubber Feet - https://ebay.to/2S9qnH3
TOOLS and MATERIALS:
- Wire Stripper - https://ebay.to/2G4x9av
- Multimeter - https://ebay.to/2GrYP9x
- Hole Saw Kit - https://ebay.to/2Wix3RY
- Center Punch - https://ebay.to/2ZJSU6N
- Hot Glue Gun - https://ebay.to/2F3bhZ5
- Sanding Sponge - https://ebay.to/2TuJhW9
- Epoxy Glue - https://ebay.to/2DtAtvk
- Jig Saw - https://ebay.to/2M4yNMF
- Drill - https://ebay.to/2JweCno
- Soldering Iron - https://ebay.to/2yYfbSF
- Solder - https://ebay.to/2S5akaD
- Soldering Stand - https://ebay.to/2HH4nOg
- Drill Bits - https://ebay.to/2HGpi4b
Step 3: Let's Start With the Enclosure
I chose the main building material for the enclosure to be 12mm MDF. You can also use plywood instead and skip the painting step and still achieve a great looking result. But for this speaker I chose the MDF since I wanted a gloss painted finish. The overall width of the enclosure needs to be at least 70mm wide therefore my intention was to cut out 6 layers of 12mm MDF resulting in a width of around 72 millimeters give or take.
I used a relatively large sheet of MDF and traced around the template 6 times making sure to leave a gap between each template tracing to allow for the jigsaw blade to cut out the pieces without interference to other pieces. It is important to trace the outside and the inside of the template. It is not necessary though to be exact with the tracing since we will adjust the lines and the curves with a router later.
Once the tracing has been done, I took a forstner bit and drilled in every corner of the traced out template making sure to stay a bit away from the inside lines. It is important to drill only halfway through to avoid any tear out on the other side. Once all the corners have been drilled halfway through, I took a drill bit and drilled all the way through to the other side. I then flipped the sheet around and used the forstner bit again to drill out the holes completely leaving me with smooth edges around.
Step 4: Cutting Out the Enclosure Pieces
For this step the best tool is a jigsaw to cut the enclosure pieces out. Take care not to cut into the line, we need to stay as close to the line as possible without cutting past it. Once the cutting is done, we are left with 6 pieces (or less, depending on the thickness of your material) of the rough template copy. Next steps will take care of the roughness and will make it more pleasant to hold.
Step 5: Router Work
This step starts by placing pieces of double-sided adhesive tape around the perimeter of the enclosure template, making sure it is stuck on well. Once the backing is removed from the tape, it is carefully stuck to the MDF piece we just cut out with decent force applied to get on there real good. It is important to stick the plywood template so that the rough edges are not in the area of the plywood template.
I then loaded a flush trim bit in to my router and started routing. A lot of nasty MDF dust will be made so make sure you use a dust collection system and a dust mask. You don't want to breathe this stuff in!
Once the flush trim router bit has gone through all the edges around, we are left with a smooth finish around. We have now copied the plywood template on to the MDF piece with nothing more than a router.
My router bit did slip under the plywood template a few times taking a bit of the material here and there therefore you can see that the edges have imperfections here and there. That is not worry about since I will take care of that later.
After a bit of work later, with the template removed, 6 pieces are now complete and are ready for glue up.
Step 6: Glue Up
To glue the MDF layers together I used Titebond III which is a great type of glue for this application since the glue is waterproof. You can also use plain wood glue, of course. Here I am making sure to spread the glue around each layer evenly. Don't be afraid to use too much glue, the excess can always be wiped off.
Stacking the layers on top is simple, just have to make sure to keep the aligned to each other and remove the excess glue from the inside and outside. Once the layers have all been stacked on top of each other, I put two boards on each side of the enclosure and clamped it well until the glue has dried. You can also use a few weights instead of clamps.
Step 7: Filling in the Imperfections
Since I will be spray painting the enclosure in gloss white, I need the enclosure to be as smooth as possible since every dent and imperfection will show through the clear coat.
Here I am mixing the same MDF sawdust with wood glue to make a filler which I will use to fill in any imperfections on the MDF.
Once the filler has fully dried it was time for sanding and smoothing the enclosure. It is not necessary to take much time on the inside of the speaker since it will not be seen later. I used a belt sander to smooth out the edges and curves on the enclosure. A sanding block can also be used but it would result in a good workout rather than an effective sanding procedure.
Once the enclosure has been fully sanded I applied the same filler once again to fill in any small spots that have appeared. Once that filler is sanded down, the enclosure is now really smooth to the touch.
Step 8: Preparing the Panels
To prepare the laser-cut panels we first need to sand any burn marks that were left from the laser. I used a random orbital sander to quickly take off the burn marks from the panels. Of course, plain sandpaper can also be used.
Once the panels were smooth I sprayed them with a few coats of clear lacquer sanding in between the dried layers of clear lacquer to remove any burrs or bubbles. That way we will achieve a smooth and glossy finish.
I then applied a thin layer of wood glue on a panel and glued it together. You can see in the pictures how the panels need to be glued together. It is important to make sure that the panels are very well aligned so take care of that as best as you can.
As you can see I should have applied the wood glue on the face panel instead rather than the backing of the front panel. But it is not a huge problem.
Step 9: More Router Work
Once the enclosure has fully dried of the fillers and glue, I used a roundover bit to give a round egde to the enclosure. I made a very light pass on one side of the enclosure and a deeper pass, removing more material on the front side of the enclosure. Once that was done, I used some sandpaper to remove any rough edges left by the router.
Step 10: More Drilling
I then put the back panel in place and drilled the holes for the screws that will hold the back panel with a small drill bit.
I also drilled a hole on the right side of the enclosure for the main switch using a 20 millimeter forstner bit.
A recess was also drilled for the plywood disc to stay in place. For that I drilled 3mm deep into the enclosure with a forstner bit the size of the plywood disc. I then used a smaller forstner bit to drill all the way through, leaving a lip around the hole for the disc to rest on. The plywood disc was then glued in place and sanded down with filler applied to the edges to fill in any gaps.
I then drilled four holes on the bottom of the enclosure for the rubber feet. It is a good idea to do this step before painting the enclosure since these holes will come in handy when painting.
Step 11: Preparing for Paint
To paint the enclosure with the color of choice, first of all we need to tackle the tricky nature of MDF panels which is its ability to absorb lots of liquid including paint that contacts its surface. In order to achieve a nice paint finish on the MDF we need to create a thick layer or a coat that would not absorb the paint in to the pores. Since I could not source a simple sealant for MDF in my country, I went with a 50-50 mixture of water and Titebond III waterproof glue. I chose Titebond III since it is used for outdoor use and will not be penetrated by liquids. I simply mixed the two and brushed a thick coat of it on the MDF enclosure and then let it thoroughly dry overnight in room temperature. Don't be afraid to apply a thick coat of it, the deeper it penetrates in to the MDF - the better.
Once the sealer has fully dried, I used some 200-400 grit sandpaper to rough up the surface for the primer coat to bite into.
Step 12: Painting the Enclosure
To begin the painting process I used a paper towel and paint thinner to remove any oils or residue on the surface of the enclosure. Once the enclosure is clean of any contaminants, I sprayed a few light coats of grey primer. Note the screws on the bottom side - that is why we drilled the rubber feet mounting holes before painting - we can now use a few screws as stands for the enclosure when painting. I am also holding the enclosure by a bolt that I ran through the potentiometer mounting hole.
After the primer coats have fully dried overnight, I wet sanded the surface with 400 grit sandpaper and a spray bottle full of water.
I then applied a few thick coats of gloss white and once that was dry, I applied a few coats of clear lacquer. After that I let the enclosure dry for a few days until the paint thinner smell was gone.
Step 13: Gluing in the Passive Radiators
On this speaker build I used three passive radiators in total since the are of these three passive radiators is double the size of the are of the woofer cone.
To glue the passive radiators in place I used two component epoxy glue which I spread around the edge of the plywood panel. I then carefully put the passive radiators in place and leaving the epoxy to cure for a few hours.
Step 14: The Battery Pack
Since I have included all the information on the wiring in the video and the wiring diagram, I will not go into much detail. Therefore I would like to provide more information about the battery pack since for most people the wiring of the battery pack is a mystery.
To build a high-power rechargeable battery pack we need three main components - Lithium Ion cells, a BMS and a power source for charging.
For the Lithium Ion cells I chose three units of NCR18650PF cells with a capacity of around 2.8Ah each. These have been used for quite some time, that is why their capacity is lower.
Since we are aiming for a voltage of around 12 Volts for the amplifier, we will be using a 3S (three cells in series) BMS (battery management system). The BMS board is a crucial component of the battery pack since it will be controlling the charging and the discharging of the battery, making sure that all the cells stay balanced and protected from short-circuits, over discharging and many other risks.
You can see a picture of the wiring diagram for the battery pack. It is really simple and easy to do. Many people are afraid to solder 18650 cells but in my experience of soldering many of these - it is safe if you take care doing it. The main point is to heat the cell when soldering for as little time as possible - therefore using a high power soldering iron and plenty of flux will do the job easily.
So to build the battery pack I laid the cells opposite to each other and glued them together with hot glue. I then stuck a piece of double sided tape on each cell ant stuck the BMS on top, making sure that the B- terminal is aligned to the negative terminal of the first cell, and the B+ terminal is facing the positive terminal of the third cell. The rest of the wiring can be seen in the pictures above.
Once the soldering is done, I protected the contacts with Kapton tape just to be safe from ant short-circuits.
Step 15: Mounting the Components
For this project I decided to use something more professional than hot glue to mount the components in place. It may be a bit of an overkill for mounting the electronics, but I used brass standoffs which were held in place by screws from the other side. That the components can be put on the standoffs and screwed down with hex nuts making them stay in place really well.
Once the components are in place, it looks like an absolute mess but almost everything is now connected!
Important: one of the main goals of this build is to make the speaker airtight. Therefore it is necessary to apply glue where air might leak through. For example - around the battery level indicator switch, the Aux port, the Bluetooth/WiFi switch and the LEDs.
I then glued the small plywood cutout for the battery level indicator switch using a small blob of two component epoxy glue.
Step 16: Gluing the Front Panel
Spreading some wood glue around the edge of the front panel and putting the enclosure on top of it. Make sure to spread some glue with your finger around the inside where the enclosure meets the front panel to seal any gaps. I then place a few weights on top and left it to fully dry.
Step 17: Paint Finish
After the paint has fully dried we can inspect the result. As we can see, even without polishing it has a high gloss that I was looking for. Under a bright light, a few imperfections are still visible but as I mentioned in the video - I will live with that. To be honest I am quite please with the paint finish result.
Step 18: Attaching the Rubber Feet
We can now attach the rubber feet to the underside of the enclosure. It can now stand on its own!
Step 19: Mounting the Woofers and Tweeters
It is now the long-waited moment of mounting the speaker drivers in place.
To mount the tweeters I simply spread some PVA glue around the edge and press fit the tweeters in place. Since they are a tight fit, I do not need to worry of the falling out anytime soon. I love the way they sit flush in the panel.
Since the woofers have a foam gasket installed, I simply bolted them down with a bolt and a nylon nut from the other side, making the woofer stay in place really well.
I soldered the speaker wires coming from the amplifier to the speaker drivers before installing them on to the panel.
Step 20: Few More Things to Do
Just a few more tasks left - such as mounting the main switch in place and securing it in place with a nut from the other side on the inside. I also mounted the volume potentiometer by scewing it in place with the supplied nut and placing the potentiometer knob.
Step 21: Last Step!
Finally we can screw the back panel in place and we are done!
Step 22: Setting Up the Speaker
All that is left to do is to charge the speaker, check the battery level with the battery level indicator we wired up and we can now connect!
As I said the speaker can play through Bluetooth, WiFi or Aux. For the demo I chose to stream a few tunes through Bluetooth. As I stated before, once the Aux is connected to the stereo jack, the Bluetooth and WiFi are disconnected without any additional switches. The WiFi audio streaming can be enabled through an app, you can find more information on how to connect it HERE.
Step 23: Final Thoughts
I have to say - I am happy the way this speaker has turned out. My apologies for the crappy sound test on the video but you will have to take my word for it - not only does it look decent but it sounds good too! I did make a few flaws here and there when building the speaker but hey - at least I learned something! And I truly hope you did too! Thank you so much for checking this project out, I hope I inspired you to build a speaker of your own. And if you are still hesitating - do it! It is super rewarding and the knowledge you get by making it is priceless. Not to mention the fun!
Thank you once again for tuning in to this project of mine and I will see you on the next one!
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