Scrap Speakers to DIY Sound System

When you think about a "surround sound" system, you proably think about it being expensive or requiring a large space and expensive equiupment such as costly amplifyers and fancy speakers. While there are decent multi directional sound speakers out there that can be had for around $500/pair, I am going to show you how I created a pair of not-as-terrible-as-I-anticipated multi directional speakers for around $20 using recycled SMART board speakers and 3d printed printed parts designed using Fusion 360.

Objectives:

1. I use whatever materials I have on hand
2. The final product must be visually appealing
3. The speakers must be designed in a way to not bother my neighbors when they are mounted on the wall

Solutions:

1. Use 3D printed parts designed in Fusion 360 and Speakers I had on hand which were purchased from my Universities surplus store.
2. The speakers will be mounted on the wall and must have an appealing aesthetic. I used some 1/4in speaker cables to clean up the wires. It was optional but I like the result.
3. The speakers are shock mounted to the wall with elastic 3mm cord to prevent the wall from vibrating and bothering my neighbors on the other side of the wall.

Supplies

Speakers

For the speakers used in this project, I disassembled four SMART brand speakers. I have since taken the speakers out of their housing and thrown them away so I took pictures from an ebay listing to show which speakers I started with. They are SMART SBID 8070i speakers. Pretty sure they are around 15W 8ohm, which is good enough for me, I'll be using four of them. They look aproximately like the 3rd-5th picture when you take them out of their housing.

2 speakers per unit were used

Other Hardware

M4 x 80mm (ct 1 per unit)

M4 x 60mm (ct 1 per unit)

M4 x 50mm (ct 6 per unit)

M4 washers (ct 16 per unit)

M4 nylon lock nut (ct 8 per unit)

M4 x 40mm button head screw (ct 8 per unit)

M3 x 20mm button head screw (ct 6 per unit)

M3 nut (ct 2 per unit)

3mm round string elastic cord

GKEEMARS lever quick connectors (optional but highly recommended, I just dislike soldering)

https://www.amazon.com/gp/product/B08JPBJDW4/ref=ppx_yo_dt_b_search_asin_title?ie=UTF8&th=1

1/4in jack female

https://www.amazon.com/gp/product/B003HLW14W/ref=ppx_yo_dt_b_search_asin_title?ie=UTF8&psc=1

1/4in jack speaker cable (it is important to get speaker cables, and NOT instrument cable. They appear identical but instrument cable is very low guage, and should not be plugged into an amplifier output)

https://www.amazon.com/gp/product/B0154LEPX2/ref=ppx_yo_dt_b_search_asin_title?ie=UTF8&psc=1

Printed Parts

I used PLA plus from ESUN, which is more than strong enough for this application. no supports needed.

Step 1: How to Design a Speaker Enclosure

Designing a proper speaker enclosure can even turn very inexpensive (and of questionable quality) speakers into competent daily drivers. The most important part is achieving a proper seal against the speaker itself as to not leak air pressure when the speaker is pushing air.

Because every action has an equal and oppisite reaction, and there are air particles on the reverse side of a speaker cone, an enclosure is required to direct and contain the oppisite pressure waves. It may require some experimentation and creating multiple enclosures of differing volumes to find one that works best for your speaker.

Step 2: Designing the Main Speaker Enclosure Back

When designing a speaker enclosure, you must conider many many factors. It is closer to rocket science than anything. One of the biggest topics to consider when designing a speaker enclosure is weather or not the enclosure will be vented or not. Venting an enclosure takes adventage of a principal called bass reflex to assist resonation at certian frequencies.

I attempted to create a fancy ported enclosure, such as the first two images were the first two attempts at designing a port that would work for my speakers. The first image is of a simple port, and the second image is of a more complicated port that used a similar concept as the stock enclosure that i removed the speaker from. The ports would have been mirrored on either side.

In the end I decided to go with no vent as my speakers did not see an advantage from bass reflex. The third image is the reinforced "no vent" design for simplicity. The "ribs" stretching across the back are to strengthen the back and prevent extra vibrations from the air pressure making the enclosure rattle.

All a part of the prototyping process. Parametric design makes it super easy to go back and try something else.

Step 3: Designing the Mount for the Enclosure

For my mount I needed something that could attach to my wall with with double sided tape and it needed to be modular so the spacers for angling the speakers are seperate pieces. The speakers use long bolts to extend the mounting points away from the wall and suspend the speaker using elastic cord. the bolts are inserted through the bottom of the part and the speakers point downwards and away from the center of the mount to help project the sound around the room.

Step 4: Printing and Assembly

These parts were printed on my custom modified Ender 3. The speakers were dropped into the speaker case and then the back cover was bolted on and sealed the speake enclosure. A small hole was included in the enclosure lid to run the wires from the tabs on the speaker componet.

The speakers were then mounted using elastic rope to the mounting base to allow for the vibrations to be isolated from the speaker base. The elastic rope was tensioned to allow the speaker to not sag on the base, but not too tight.

A terminal block was screwed onto the base in the middle to remove the need for soldering. Then the 1/4in jack reciever was mounted in place with wires coming off of its terminals and going into the terminal block. The terminal block and 1/4in jack reciever are completely optional but I prefer to design things to be modular, so these speakers are now fully "plug-n-play".

Now that the speakers are complete, it was time to mount them on the wall and for this task I have used thick double sided adhesive.

Thank you and hope this helps you with any future DIY speaker projects you may attempt.