What it offers?
Hello everyone, hope you all are having fun around DIYs. This time I’m back with a special 360 degree portable speaker which is a bit different from the typical ones out there. It uses 6 individual speaker drivers (a pair of woofers, tweeters, and passive radiators) coupled with a pair of audio crossovers to enhances the low, mid, and high audio frequencies.
The drivers are evenly placed around the wooden enclosure to cover the entire 360 degrees. This particular arrangement uniformly fills the sound at every corner of the room. I don’t know how to put this into words but, it’s a lot different when compared to front firing speakers. To make things better, I have gone for a wooden enclosure where the denser walls pamper the overall sound quality. To take things further, the bass boost & treble boost option allows us to customize the tone to our preferences.
It also comes with some user friendly features too! The foldable handle makes it super adaptable for our daily commute. Thanks to the dual Li-ion cells, it have a huge battery backup and thus making it a nonstop entertainer.
Further, it have a dedicated switch to toggle from battery mode to Line-in mode. The later would be helpful to directly drive the amplifier from an external USB charger without draining the battery. Also it helps to simultaneously charge and power the speaker directly from the USB port. Here, a part of the input power is separately fed for charging and powering the amplifier. This reduces the strain on the battery due to continuous charging and discharging as seen in other portable speakers.
As far as indications are concerned, it comes with a battery level display and charging and full charge indication at the top. So what do you think about the speaker? Getting interested to see the entire build? Then the remaining steps are waiting for you.
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Step 1: Templates & Wooden Enclosure
In order to arrange the speaker drivers for our desired function and utilizing the maximum enclosure volume demands a different sort of enclosure design. So I followed the layered enclosure technique where, several wooden cut outs were stacked vertically to form a single pile structure.
The template cut outs (pdf files) have been attached along with this article. Just print it out and glue on top of plywood and cut along the lines with a jig saw.
For convenience, I have named the templates as mentioned below. Note that, I would also address the final wooden cut outs with the same names.
1) Bottom circle section (only 1 needed)
2) Main enclosure section (7 of these needed)
3) Top section part 1 (only 1 needed)
4) Top section part 2 (only 1 needed)
5) Handle section (only 1 needed)
Out of these five, the top template part 2 and the handle template were cut out from a 3mm thick plywood and the rest were from 12mm plywood.
Once the outer lines are properly cut out, few holes have been drilled inside so that a jig saw blade would go through and cut the inner sides as well.
Once all the cut outs are done, peel off the paper templates and do some minor sanding for good surface result. Then, using wood glue and brad nails, the 7 main enclosure sections were stacked & placed over the bottom circle section.
The top section part 2 is now fixed over the top section part 1 with wood glues and brad nails. This section would be attached to the previous enclosure setup at the final stage of the build along with the handle section
Please note- By joining both the top sections, the 5 switch cutouts on top section part 2 is closed by the part 1. So we have to re-cut those 5 cutouts again.
How did I came up with the template design?
I think, it would be a good idea to share the thought process went behind the template design. You could totally skip to next if you don’t want to go into these details.
So, the main aspect of the design was, finding out the outer diameter of the enclosure. The dimension is chosen in such a way that, it should be portable and also have enough internal volume to accommodate all the speaker drivers and circuits. So procuring all the components before the build would be the best way to start the project. After some trial and error I found out that, a radius of 7cm would be a perfect fit for the enclosure. I arrived at this result by drawing a circle on a paper with a rough estimate value for the radius. Then placing the drivers and circuits over the drawing to see whether it would be a good fit. If not, change the diameter to a larger value and repeat the process until a sweet spot is reached.
Step 2: Speaker Drivers and Cut Outs
Once we are done with the wooden enclosure, we could start cutting out the holes for the 6 speaker drivers. The passive radiators, woofers, and tweeters which I have used are of 2.25 inch, 2 inch and 1.25 inch respectively. Since I have used a 3W+3W amplifier for this project any drivers rated above 3W would be fine to use. But it’s better to stick close to the amplifier wattage rating. The woofers are of 5W and 4 ohms, tweeters are of 20W and 4 ohms.
The wider part of the enclosure would be the rear side, which at a later stage, encloses a passive radiator with two tweeters on either side. At the front, another passive radiator would be arranged with two woofers on its either side.
Using a compass, a rough circle is drawn on all the 6 faces according to the dimension of the drivers. This helps us to find the center and proper position of the drivers. Now, using the corresponding hole saw attachments, the cutouts are made on all the 6 faces of the enclosure. This step is then followed by drilling all the screw holes for those speaker drivers.
Step 3: Speaker Grill
The speaker grill is fairly simple to make. I used two pieces of half round PVC pipes (5 inches) which are commonly available as rain water gutter pipes in hardware stores.
At a final stage, it fits between the top and bottom sections of the enclosure and conceals all the speaker drivers. The one that sits between the top and bottom is the previously explained main enclosure section. So briefly speaking, the speaker grill should have a length equal to the total height of the 7 main enclosure sections (7x 12mm = 84mm). These are then place around the enclosure to mark the outline of all the 6 speaker cutouts. Some grill templates (attached in images) are now glued on top of these outlines and it’s drilled to get the desired grill pattern. This two sections are then joined together using a piece of jute cloth and rubber adhesive (aka rubber cement). All the cloth edges have also been folded and glued to get a good finish. Folding the cloth would surely ads up to the total length and therefore it’s better to take the PVC length as 80mm rather than the previously mentioned 84mm as a factor of allowance. However, the jute covers all the grill holes which are again reopened with a hot soldering iron. The result was further covered with a final layer of black speaker grill cloth.
Step 4: Electronic Components
The circuits used for this project are as follows
1. 3W+3W amplifier
2. Two way audio crossovers (two of them needed)
3. DC-DC Boost converter module
4. Li-ion cells (two of them needed)
5. Li-ion charging module
6. Li-ion battery level indicator
Out of these, the first four i.e. the amplifier, crossovers, boost converter, and the LI-ion cells are arranged above a glass fiber sheet which have the same internal dimension of the enclosure. The layout of the circuits are drawn on the sheet and the screw holes are made with a hot soldering iron. It is now inserted into our previously made wooden enclosure to drill holes at the exact location as that of the sheet. Please check out the video to have a better understanding.
The glass fiber sheet helps to secure the Li ion cells and the boost converter with zip ties since, these two don’t comes with any screw holes for attachment. We could also use hot glue for the purpose but I believe it’s rather not a permanent fixing method and would eventually loses the bond over time. The sheet also insulate the heat from the electronics to the wood beneath it and provide safety against any worst case scenario.
The rest of the modules i.e. the charging module and battery level indicator were arranged within the top section and would be discussed in later sections.
As you can see, I have use Li-ion cells in parallel configuration for more battery backup. Before connection the cells in parallel, it’s very important to fully charge each cells individually. If not, the higher voltage cell would charge the lower voltage one uncontrollably, which is not at all a good thing to do.
After the cells are fixed with zip ties, we could tape wires by soldering from its terminals. Before arranging the rest of the circuits, make sure you have soldered wires from all its terminals as well. In order to make room for the crossovers, they are arranged vertically with some bolts and nuts. The boost converter is now fixed with zip ties and the voltage is set to 5V by turning the potentiometer on board. We could temporarily power the module with the battery pack at its input and use a multimeter at the output to set the value at 5V. Ones it’s done, we could place the crossovers and amplifier board over the glass fiber sheet. But before inserting the circuits into the enclosure, a hole is drilled at one side of the bottom for fixing the USB port. It’s secured properly with the help of some epoxy putty. Now we could insert the circuits into the enclosure and fix with screws. The 4 bolts from the crossovers are fixed with bolts on the bottom side of the enclosure.
Step 5: Fixing the Speaker Drivers
As mentioned before, we have a total 6 individual speaker drivers for the project. The passive radiators and the tweeters were fixed first. It was a bit hard to find thinner screws which could go through their screw holes and hence they were fixed with bolts. Using a pair of pliers, the bolts were fastened with nuts and the remaining length of bolts were cut off using hack saw. The connection wires from the crossovers were now soldered on to the tweeter terminals. Similarly the two woofers were wired accordingly and fixed with screws. Things are almost done with the enclosure section. Let move on to other sections.
Step 6: The Handle
As previously explained, we have already cut out the handle at the beginning, along with other sections. Now we have to work on the joint on which it should be attached to the top section. I have used two small metal hinges for this purpose. Since the hinge area is very small, we can’t properly fix it to the ends of the wooden handle. So, a metal piece cut from an L-clamp is bolt fixed on one side of the hinge so that its length is extended. This could now be attached to the handle using another set of bolt. The same thing is repeated on the other side and the whole wooden part of the handle is glued and covered with jute cloth.
Step 7: The Top Section
As you can see from the picture, the top section have 5 switch holes and two gutter areas for fixing the charging module and the battery level indicator. Necessary holes have been drilled on to these gutters so that, the wire connections from these two module could go through. Some minor adjustments should be made on to the top sections for perfectly fitting these 2 modules. Like, you could glue small plywood pieces on the gutters to raise the battery level indicator so that it’s even on the surface. Since charging module would be covered, there is no need to align it evenly to the top surface. However, for the indication lights of the charging module to be visible, it is covered with a piece of 2mm white acrylic sheet. It’s placed in the Small guide way border made on top of the wooden gutter around the charging module. A sharp utility knife would be enough to cut the wood for the guide ways. This whole top section is covered in jute cloth similar to before. However we need to precisely cut the cloth at the portion of battery display indicator and charging light indication, to expose it. What I have done is, used a transparent tape over these two modules and with a marker, precisely traced out the boarders. This tape is then stuck on the center of a jute cloth and used a pointed end hot soldering iron to burn and cut these portions.
Jute cloth are super easy to cut using soldering iron tip and also the edges would nicely burn and would not get threaded out. This is one of the main reason that I use jute a lot on my projects. Also, its lower cost and rough texture always attracts me towards it.
The cloth is then glued on the top section using rubber adhesive just like explained in earlier steps.
Now we could attach the previously explained handle on to the top section by fixing the two hinges on place with bolts.
Step 8: The Final Assembly
We could now insert the 5 DPDT switches on the corresponding cut out on the top section. The switches are mentioned below and its position on the top section are labelled on the image.
1) On/Off switch
2) Bass boost switch
3) Treble boost switch
4) Battery level switch
5) Charging switch
The dimension of the switches are
Width - 13.1 mm, Length- 19mm,Height- 18.7mm (approximate value)
One thing to note is that, the On/Off DPDT switch should have a center off position. This is to accommodate the toggle function between line in mode and battery mode as explained in the introduction. You could get a better idea while going through the wiring diagram. The remaining 4 switches don’t need any center off position and a two position DPDT switch will do.
Once the switches are inserted, we could start the wiring and soldering process. Refer the wiring diagram attached in the image section. I believe there is nothing special to mention about the wiring, it’s plain and simple. If you need any further help regarding it, let me know in the comment section below.
For creating an air tight seal, we should seal off the switches from the back to prevent any air leak through the gaps around the switches. Using epoxy putty would be a good choice to do it.
So things are almost done! We could now finally join the top section over the main enclosure section. Apply some wood glue on the enclosure surface and drive 4 screws on the top section to fix it securely.. Since we are fixing it with screws, we could open the section any time in future for any customizations or repairs. Just unscrew the screws and glide in a putty blade or something to separate the glue and you could surely open the enclosure without much effort.
Before attaching the speaker grill, make sure that you have cut a notch to expose the USB port at the bottom. The only thing left now is the speaker grill so, attach it to the enclosure with screws.
So The project finally complete. Now we could finally relax a bit to the pleasant sound from this speaker. I would highly recommend this project for those who are looking for building a portable speaker. Though it’s a bit time consuming, Its definitely a step further than the usual two driver setup. So the effort is totally worth it. So what do you think about this project? Do let me know in the comment section. Also if you have any questions regarding it, I’m glad to hear it.