Introduction: The Ultimate Portable Home/Shop Bluetooth Speaker
This is my Entry into the Plywood contest, give me a thumbs up and vote for me.. Thanks :)
EDIT: I HAVE ADDED THE DXF FILES FOR THOSE WHO HAVE ASKED
A few months ago a friend brought a Bose Bluetooth speaker to a camp out, I was amazed at how full and clear it sounded, and was convinced I was going to buy one the next day until I saw the price tag. Ahead you will learn to build an amazing sounding Bluetooth Speaker that's Stylish as well as easy to build, Lasts for days on a single charge as well as having a quick change of battery to keep on jamming, and last but certainly not least pretty easy on your wallet, in fact this project cost me less than 100 bucks even with me buying almost every piece, chances are with a little scavenging you could build this for under 50. Let me stress that anyone can do this and its not as hard as you think, and when your done its something you can brag to your friends about which we all know is the most important thing right? Lets dive into this and start gathering and designing this bad boy.
What I Want Out Of This Build:
1.- Loud and clear enough for me to use in the garages while working on my cars or etc...
2.- Portable with plenty of battery life for weekend camping or a long night out by the ManPit ( https://www.instructables.com/id/Build-An-Ultimate-... )
3.- Stylish enough that my old lady will allow it in the house for jamming while we cook or clean the house.
4.- Budget build, under 100 Bucks but without it looking budget.
Thoughts About The Design:
After deciding to start this project the first thing I had to do was round up parts and design some things, without having any of the electronics besides speaker wire laying around I couldn't design the whole project but I could start brainstorming. In projects like this I always try to acquire the electronics and then build around them instead of designing an enclosure and then trying to get electronics that fit. So with that in mind lets order some parts.
Step 1: Acquire Parts
Parts List And Explanation
Power Supply: http://www.harborfreight.com/18-volt-nicd-replace...
Originally I was starting to design the speaker around a lithium battery that one would use in RC applications, however after a day in the shop I remembered as a kid we had a DeWalt shop radio that you could run off of the drill battery an we loved it, took it on the boat, camping, to the Drive-In (That is right we still have Drive-Ins in KY). It was from this that I decided on the drill battery, however you can use anything, the amplifier supports 8-30v dc so about anything you can steal a battery from will work, old RC cars, other brand tools, cell phones etc...
Charger / Mount: http://www.harborfreight.com/18-Volt-NiCd-Battery...
Bought two. While thinking about how to make it to where the battery would click into the speaker like it does the drill I though well why not just buy two chargers and tear one apart and use it as the mount for the battery onto the speaker, especially since its only 6.99. Turned out to work perfect as you will see later, you could get away with one charger and just keep the charging circuit intact inside the speaker so you could plug your speaker up and charge the battery when you wasn't using it but i like to have all my battery chargers on the wall of my garage with my different drill an what not batteries charging away. plus I didn't want to be carrying around a brick and the NiCad battery was already heavy enough
Amplifier: TDA7492P 2x50W Wireless Bluetooth 4.0 Audio Receiver Amplifier
This was actually the first piece bought and everything was designed around it. I had seen a YouTube review on a cheap but powerful Bluetooth amplifier that was 2 x 50 Watts for 15 bucks from china, I was instantly sold after seeing it perform on a set of bookshelf speakers during the review. Theirs also other alternatives like the ones with the AUX inputs and other alternatives to suit your needs.
Drivers (SPEAKERS): Vifa TC9FD-18-08 3-1/2" Full Range Paper Cone Woofer
The most difficult decision on the build, whether to go with single full range speakers or add a tweeter into the mix. after reading literally a couple hundred reviews I made the decision on a couple of these set in full range for the project and let me tell you I am super happy about that decision, LOUD, CLEAR and just all around amazing speakers an a price tag that is perfect at under 12 bucks a piece. I purchased mine from PartsExpress.com they have amazing prices an sooooo much audio stuff, check them out.
Enclosure: 1/2" Birch Plywood. Half Sheet. 1/4" MDF or ply. 15"x5" piece.
I went with a Plywood Enclosure ( Yes I know that MDF is better for audio but when I saw that some plywood I had laying around had two beautiful very dark layers in the middle I decided that it would look great with some polyurethane on it). Took about a third of a sheet of 1/2" birch plywood, less if you have 3/4" laying round.
Step 2: Design a Stylish, Good Acoustic Box
Now for me this is the most fun part, three years ago I began teaching myself CAD. Started with Sketchup, and eventually moved up to Solidworks. I than designed and built a CNC Router from scratch and now I use it to do little projects around the house and for people. One of these days I'm going to do a write up on the build of it but for now lets get back to the Speaker project.
I began by measuring the battery knowing I wanted it to be on the bottom for a low Center Of Gravity and in the center for good balance. I then designed the two independent and sealed enclosures based off of the specs given about the driver from the PartsExpress.com website. I ended up a little over .06 Cubic ft per side which is pretty decent, I may add some polyfil in order to make the drivers think they are in a slightly larger enclosure or of course you could always add or subtract "slices" from the design in order to accommodate drivers you already have laying around. I wanted something that looked stylish and not like it was thrown together which if your anything like me you've been known to do, something that looked bought and not home made. In the beginning I started with just a rectangle box with a cutout for the battery, which I immediately changed to rounded ends which I thought was much better looking.
Let me stress that you don't have to have a CNC in order to do this project. use a jigsaw to cut a template and then a router with a flush cut bit in order to replicate the slices and it will turn out just as good trust me I've done it.
Step 3: Cut, Glue and Sand
Cut: CNC or Jigsaw and Flush Trim Router.
Unfortunately I dont have any pictures of the machine cutting out the parts however I will be making another and try for some pictures and videos, but after you get your pieces cut out then its time to glue the center section together, 9 pieces of plywood.
I took some 1/8" welding rod and used it to line up the pieces applying glue generously in between every layer as you can see ( Make sure you wipe the excess off with a damp rag after all 9 slices are stuck together. Now I laid a 2x4 across the entire setup and placed a cinder block on top while the glue dried. If I could do it again I would clamp it due to I had one spot that had a very small gap that was only noticeable by me holding it up to the light and looking inside the enclosure, but other than that it worked great.
Next its time to sand sand sand. I started with some 80 grit on a sanding block to knock off all the burs inside and out, then moved on to 120 on a electric orbital sander and sanded the outside of the center section to uniform size and smoothness up to 220. In retrospect I should have installed the front, back and grill and sanded all together
Step 4: Modify a Charger to Be Power Input From Battery.
Tear down of Charger:
This part actually worked out so much better than I had planned, I was ready to get the Dremel out and hack things up but was almost sad to see harbor freight had took all the engineering out of the task. Upon taking apart the case of the charger I noticed the section that I needed would just unscrew from the base. literally cut three wires and unscrew 8 little screws and I had just what I needed, it was already flat and had screw holes. The only thing I did was make through holes and countersink so I could run machine screws through the charger up into the box with a nut instead of having to come from the box down into the charger ( see picture 6 and 7 you can see the modification I did )
I also found a neat trick for drilling holes to mount something that doesn't have through holes. Scan whatever you want to make a template of then flip it over then you have a perfect pattern to go off of to drill ( See Picture 5 )
Test Fit and Drill
After drilling all the way through the four holes on the charger and countersinking I test fitted it on the enclosure and used it as a template to drill the holes into the enclosure for both the bolts and the wires, only the + and - wires are needed so you can clip the other.
Step 5: Test Electronics and Enclosure
Now Comes Some Fun:
Wire up your electronics, its about as basic as a circuit can get. power in and two sets of speaker outs, of course the Positive of the battery goes to the positive of the amp and negative to negative, be sure to get the speakers wired in sync together the two inside terminals of the board are negative and the two outside are positive. Now with the battery inserted into the charger base that you robbed you should hear an audible beep from the speakers followed by a pause and another beep telling you it is ready to be paired with. There was no passcode and it paired quickly, I fired up IHEARTRADIO and away it went.
Design Change: ( well more of an addition )
At this point I was ready to jam for a while for a time study to see how it did. With everything mounted I cranked it and listened for several hours one night while having a get together with some friends. That night I also decided I needed a nice speaker grill to cover everything, and as you can see it turned out pretty well. Created a nice decorative pocket without interfering with the speakers followed by a press fitted insert that I used to stretch and hold some speaker cloth in place.
Now that everything works disassemble it all so we can make it look good.
Step 6: Sand, Stain, Clear
Sand, Stain, Clear :
Now get out the orbital with some 220 once again and give it a once over with all the panels one to ensure all surfaces are uniform. Once your happy break out the stain or in my case I just decided to polyurethane it as it was due to the wide spectrum of light and dark colored wood inside the plys. Apply two coats of polyurethane waiting a day in between each coat if its cool out like it is here. Then give it a good 220 grit sanding all over and apply a third and final coat letting it cure overnight. I used minwax high build matte clear finish from walmart. good stuff had this can for like 2 years and still have alot left. ALMOST THERE.......
Step 7: Final Assembly and Jamming Out
Its All Coming Together Now:
Now were in the home stretch. Assemble everything taking special care for cable management. to get a good seal use caulk to seal up the back. with everything back together you can admire your handy work. turn it on and jam out. i can honestly say this was one of the coolest projects I've made to date and definitely one of the most handy now no matter which garage I'm in or the house I can jam out. In the future I will add usb ports to allow charging of the phone, some sort of handle or carrying strap and a power button, for now anytime the battery is in it, its being used. Feel free to write about anything that needs clearing up an I will do my best.
Step 8: Afterthoughts: Upgrade 1.... on Off Switch
Small add on here. I used a latching pushbutton I found on amazon. basically it works like a light switch. u take the positive wire that is currently between the battery + and amplifier, and cut said wire. Wire the battery side to the terminal labeled C and the amplifier side to the terminal labeled NO (Normally open) and voila. if u buy a lighted one you need to have two wires come off of the NO side, one to the amplifier to power it up and one to the + terminal on the latching switch to provide positive power to the light. then run a wire from the negative battery wire to the - terminal on the switch. Not necessary but after having it I would recommend it. next I will be working on a USB port to charge phones and also may create detachable strap or something for hands free carrying