"Old School Boombox" Style Bluetooth Speaker

I needed a new audio system for use by the pool. I wanted/needed Bluetooth capabilities, good sounding audio reproduction, decent power, weather/water resistant, low cost, great looks and portability. Something resembling an 80s style larger boombox came to mind, but that was not a firm requirement. I explored hard wired stereo systems (had many shortcomings and pricey!), available portable stereo systems (mostly overpriced junk with branding) and found nothing that suited my requirements. So what's a person to do... DESIGN and BUILD YOUR OWN!

Tools:

AutoDesk Inventor, AutoCAD or FUSION Design Software

Handheld Jigsaw

OneFinity Foreman Elite CNC Router (optional)

Cordless Drill and drill bits

Cordless Driver and driver bits to suit the fasteners (can substitute a drill with driver bits)

FlashForge 3D Printer (optional)

Basic Handtools

Materials:

1 ea- 3/4" Black HDPE Sheet (4'x8") [Junkyard Find]

280 pcs - CAMO #8 x 1-5/8-in Wood to Wood Screws [Menards]

2 ea. - 4" Stainless Steel Handle Style Drawer Pulls [Menards]

2 ea. - 32" Stainless Steel Handle Style Drawer Pulls [ Menards]

6 ea. - Stainless Steel Corner Protectors (for professional audio equipment) [Amazon]

2 ea. - 3" Luggage Replacement Wheels [Amazon]

Electronics:

2 pairs- BOSS BE524 Rage 6.5" 4-Way Full-Range Speakers [Parts Express Part # 265-4071]

2 ea.- Lanzar MAXP104D 10" 1200 Watt DVC Subwoofers, [Parts Express Part # 292-2586]

1 ea. - TPS3116D2 Class D 2.1 Bluetooth 5.0 Amplifier Board 2 x 50W + 100W with Filter and Volume Controls

[Parts Express Part # 320-635]

1 ea. - Repurposed USB Wall wart Universal Charger [Misc. Electronics Junk bin]

1 ea. - Repurposed 12v Wall wart power supply [Misc. Electronics Junk bin]

1 ea. - Mean Well LRS-150-24 Switching Power Supply, [Amazon]

1 ea. - SPST Round Rocker Switch with Red Illumination 13A 125VAC [Parts ExpressPart # 060-716]

10' - 12ga speaker wire (for subs) [Menards]

4' - 18 ga power wire (multiple colors) [Menards]

1 ea, - Repurposed power cord from vacuum cleaner (12' long) [Junk Bin]

Other:

3D Printed Face Plate for Controls

3D Printed Face Plate for USB Charger and Power Switch

2 ea. - Brackets to suit Luggage wheels made from alum. angle

First I began by developing my mental image of what I wanted using AUTODESK Inventor Design Software. Given that I desired to use two 10" Lanzar subwoofers, the enclosure requirements are defined by the manufacturer. This gave me a basic idea of the dimensions I needed to start with in order to accommodate the sub speakers. For these speakers 1.63 CF was the recommended size per ported box enclosure. Using this volume, the diameter of the speaker, the length, height and width of the required ports, the Inventor software made it easy to create my new Boombox shell. Honestly, it ended up being much larger than I had originally anticipated, but in a good way!

Using Inventor, it was very easy create the CAM files using the DXF export feature. By opening each individual component from the model, all it takes is to right click the face to be profiled by the CNC, save it as a DXF file and import into the G Code generator. AutoDesk products seamlessly integrate with Masso (the Onefinity's CNC Controller). The same DXF files could be used to create full scale templates suitable for use with a handheld jigsaw or the like in the event you prefer to do cut out the parts manually. In addition, I used the DXF exporting function to create .stl files for my 3D printer to create a faceplate for the controller and power button. This is not necessary and simply a fancy touch.

Thankfully I have the luxury of a CNC machine to cut out the parts, but this is not necessary at all. In fact in some ways using regular hand held power tools would have been easier using Autodesk created templates as I mentioned in the previous step. In my case importing the component parts into the router controller and running them was probably the easiest of all the steps in making this unit because I could start the machine and walk away. There were 13 total parts, many of which are mirrored copies of each other.

(NOTE: I wanted to add a video of the machine in operation but was not able to here due to the Inventables system constraints. It is fun and memorizing to watch! The pics here were taken from that video.)

After all the parts were cut out I hand deburred them and performed a dry fit to ensure all fit together correctly. Everything did so I had no surprises here. This is the beauty of using a CNC machine and a HUGE benefit of using Autodesk modeling/CAD software such as AutoCAD, Fusion or Inventor in such a project. If you do your work correctly up front in the computer aided design the final product is usually correct with all parts uniform on the first try.

To wire the system with the Parts Express Controller amp the speaker impendences had to be configured so as to be compatible and not overload it. This controller amp is rated at 4 ohms x 2 (R/L) and 2 ohms x 1 (subs) Given that I am using two subwoofers which are dual voice coils at 4 ohms ea., and four, 6.5" speakers at 4 ohms ea., I had to get creative in the wiring. For the subs I wired the voice coils in parallel (making a 2 ohm load for each speaker) and then wired each speaker in series mono so that the amp sees a 4 ohm total load. For the 6.5" speakers I (knowing better!) first tried wiring them in parallel (producing a 2 ohm load each channel for the amp). The amp did not like the 2 ohm load and started distorting and clipping at higher volumes, so I had no choice but to rewire them in series (producing an 8 ohm load for the amp per channel). Now the amp was much happier and proved to work fine while still producing adequate power for higher volumes without any unnecessary clipping or distortion. In the end I am quite happy with how this configuration works.

In conclusion, this "Old School" style boom box works very well. It accomplished my goal of being inexpensive (I invested less than $150 total (buying many of the parts on clearance and having others laying around in my repurposing bins), it has very good audio sound and really rocks the area, so much in fact it can be heard two blocks away quite clearly, and it looks super cool! I have received numerous compliments. This was an easy project that anyone with basic tools and desire can handle, so go for it!