Introduction: Portable Bluetooth Speaker Made From Scrap Wood
Hello everyone, its been a long time since i last posted here so i thought i'm gonna publish my current project. In the past i made few portable speakers but most of them were made from plastic/acrylic since its easy to work with and doesnt require many tools. This time i wanted to experiment with wood instead, giving speaker nice wooden look that many dont have. I saw Barry Llewellyns youtube video a while ago where he made 10W speaker and always wanted to make it. Since i recently got decent jigsaw and didn't have anything to do over the weekend this was just a perfect project for me. I had some speakers, amplifier and other components laying around from other projects so this didnt cost me anything except my time. While it may not be best speaker on market or in DIY area, it still provides enough volume with 2 40mm fullrange drivers powered by 2x3W stereo amplifier and 3000mAh Lithium battery.
Before starting, i'm well aware that some ways and techniques i used in this building might not be most efficient or should be done differently, this was my first project with wood like this so i'm still learning. Any tips and corrections are welcome.
So without further ado lets start with building.
Step 1: Parts List
Parts & modules :
- 2 40mm speakers
- 2x3W PAM8403 Amplifier
- 5v Bluetooth audio receiver
- TP4056 charging module with battery protection
- MT3608 DC DC Step up module or other 5V step up converter
- Lithium Battery of your choice (2Ah 18650 and 1Ah phone battery in my case)
- 2 LEDs, white for turn on indication and red for charging indicator
- 2 1000uF 6.3v-16v capacitors
- Wood of your choice (any hardwood, mine was scrap oak that was used as firewood)
- 2x 10kOhm resistors and 2x 220nF capacitors for RC high pass filter (this is optional, it will remove frequencies under 70hz to remove some stress from speakers since they cant produce anything lower)
- Rotary tool
- Glue gun
- Belt or orbital sander
These are materials i used, however you could use bluetooth amplifier board which has both bluetooth and amplifier connected together. This will save you some space and time. You can also skip 2 LEDs if you dont need any indication on front and capacitors on input/output but i would suggest you to use those. Standard TP4056 without battery protection can be used if you have protected lithium battery. Whole thing will cost you about 15€ depending on what speakers and batteries you use and where you get them.
Step 2: Where to Get Parts and Materials
Alternative to buying some of your parts is to recycle or salvage them. If you have old bluetooth speaker that isnt working, or its working but you want new enclosure and maybe upgrade your battery life you can just use that. Maybe you have old set of pc speakers laying around that you want to convert to bluetooth and make it portable, possibilities are endless.
Capacitors and on/off switch can be salvaged from old electronic devices.
Laptop batteries are good source of 18650 batteries, old cellphones also have usable lithium cell but if you do go this way make sure to measure capacity first. You dont want to complete your speaker just to realize batteries have low capacity and can barely work for few minutes.
Scrap wood can be bought cheaply or you might already have it at home just waiting for you to make something with it.
I got my speakers from old bluetooth speaker that wasnt working, i even bought 4 speakers from ebay to compare them since they looked similar. Ebay ones felt a bit cheaper as far as build quality goes, had less excursion and didnt sound as clean. They also started acting weird when bass hit with more than 2W, that could be due to the fact that i didnt use high pass filter, but they are still good drivers to use.
Useful instructables and guides:
Step 3: Cutting Wood
First you need to set yourself dimension of speaker. Mine was about 15x5.5x5 cm (supposed to be, wood i used was 4 cm thick so with front & back panels it should be close to 5 cm), get market or pen and draw everything on wood.
Drill 2 holes in opposite corners on "inside" part of your speaker. Since its easier to cut with bigger wood piece because you have something to hold on, start with your cut on inside part of your speaker. Use 2 holes that you made to insert jigsaw blade and start cutting. After you done that, cut outside line. You should have square frame now, you can leave it as is and sand later, or do some sanding now. Its good time to straighten front and back where your panels will go. Depending on how thick your wood was and your desired speaker size, you can cut multiple frames and glue them together later.
Be careful when cutting, its easier to do multiple layers since i figured out 4 cm was pushing my jigsaw to limit, blade got hot really fast. Sorry for no picture of me cutting it here, i later realized i don't have any.
Use protection when cutting.
Step 4: Front & Rear Panels
Since i didn't have any thin board that would fit front, i used two pieces of wood glued together and sanded to get flat board.
This will give speakers that line on panel in front of it, it was unintentional since i didn't have anything to work with, but some of you might like it, maybe you can even use different types of wood to give it nice look.
You can skip this step if you have thin board, or even want to use acrylic sheets.
Step 5: Front Panel
I glued front panel first, to give some strength to front panel so it wont break when im cutting 2 holes for speakers.
If you have thin board you can glue rear one first if its easier.
My first thought was to use hole cutter since it would give nice smooth holes, but i had bad experience with it so i drilled few small holes with drill and just sand them afterwards. They weren't good as i was hoping to, but they were good enough for me. Put good amount of glue (make sure it will be well sealed) and put something on top of it to create pressure.
When waiting for glue to dry go to next step and solder electronics together.
Step 6: Electronics
This step will depend on what type of components you got, but basically you have to connect battery to TP4056 module on B+ and B-. Output + and - from module go to IN + and IN- of your step up module. Now its good time to connect multimeter to output and adjust potentiometer to get 5V on output. PAM8403 can take up to 6v, but try to stay under 5.5v since i burned mine going to 6v. From there you need to solder your amplifier and bluetooth module, also solder L/R/Ground from receiver to amplifier. If you have bluetooth amplifier board just connect 5v output to 5v amplifier input. Connect L/R speaker according to position you are gonna put them. Use diagram on last picture if its easier for you that way.
If you have any questions about this just ask me in the comments, i'm gonna try to answer it, if i wont be able there might be someone who knows.
Step 7: Electronics and Rear Panel
Now its good time to check if everything fits inside of your enclosure.
At this point i glued speakers with hot glue and used some silicon to make sure there were no air leaks around speaker.
My first idea was to use 2-3 phone batteries to get about 3Ah of capacity, but after messing around with components i decided to go with 1 18650 and 1 cell phone battery since i can fit that easily. Check if everything works before closing everything together.
Cut holes for charging and on/off switch using rotary tool and smooth them off with file or grinding attachment. Apply good amount of glue and put some heavy load on back of it. Try to seal enclosure as best as you can since air leaks can make ugly and unwanted noise.
If you have time you can also test runtime of your batteries, for me 3Ah lasted about 20 hours of casual listening, and about 8h having it on full blast. This was confirmed with my previous speakers, 1Ah was enough for daily listening on normal levels, while 4Ah was more than enough since class D amps are really efficient. Try to find balance between what you can fit in your enclosure and how much capacity you actually need for your needs. Some may prefer smaller, lighter speaker and some may prefer bigger speaker with longer runtime.
Step 8: Sanding and Finishing
When glue is dried you can sand front and rear panels to fit frame. This is final step so take some time. Start with less grit sandpaper and gradually go up. I started with 100 to really get that wood in shape and gradually went up to 240 to get that smooth finish (you can go all the way up to get that silky smooth finish). At this point i also made small hole where i can put keychain ring and attach carabiner to it. I did this so i can hook up speakers to my backpack, or when im working something in garage or on table and have no space to put speaker, i can just attach it to something and let it hang. If you want you can paint speaker enclosure, or use wood finish to leave that wood look and give speaker extra layer of protection. Maybe even get two tone finish, black or white panels and wood frame. Put rubber feets on bottom of your speakers and you are pretty much done.
Step 9: My Other Speakers & Ideas
Here are some of my other builds that i made over the years to experiment with different enclosure materials and layouts. I modded pc speakers to be portable 7 years ago, but my first custom built portable speaker was over 6 years ago, without bluetooth since that was pretty much unknown to me back then. After that i made few more but unfortunately for some of them i don't have pictures, some of them were even inspired by ASCAS and his builds. At one point i even wanted to make waterproof speaker but that didnt end up as planned, it was splashproof but not fully submersible which most of you noticed before me.
Links in case you want to see them.
Now some things that should have been changed :
- Use bluetooth amplifier board (saves some space, less hum)
- Use better amplifier module (with more power, giving headroom for those speakers, at least 3-4W at 1% THD)
- Get ground isolator (this configuration has some hum so if you want to go this way, use isolator)
- Include microphone or some buttons to play/pause, skip, change volume etc.
- Add passive radiator to increase lower range output
- 3.5mm jack