Build a HiFi Stereo System for LESS THAN $15!

This Instructable details how to build a simple stereo system that runs off a 3.5mm auxiliary jack. It can be used for a PC, a Stereo Deck, or anything else! It requires soldering skills, but other than that, anyone can make it! The speakers are highly affordable and feature top-notch audio quality.

I created this setup because I have always struggled with good audio for my PC, and I have always been passionate about audio and DIY. I enjoy creating and innovating, and this project was perfect due to its low price point, use of creativity, simplicity, and quality.

1. 2 Bookshelf speakers, ideally full-range speakers, with tweeters from Goodwill or your Thrift Store of choice. (Make sure the speakers ONLY have the red and black terminal on the back, with no power plug. (Passive speaker)
2. (approx. $10 to $12)

1. PAM8403 Amplifier 5W+5W PowerAmp Board. Often comes with a potentiometer Volume Control.
2. (You can get 5 for $5 on Amazon, making each one $1)
3. https://tinyurl.com/pam8403shop

1. Old Aux Cable
2. (Get it off old headphones for free, often just lying around)

1. Additionally, you will need a soldering iron and wire, along with basic tools such as scissors.

Optional Materials: 3D printer, multimeter.

If you have a 3D printer, first 3D print the enclosure for the PowerAmp using the PAM8403 module. It boosts Line Level signal (from your PC) to Speaker Level Signal (enough power to vibrate the cones on your speaker). The enclosure protects the board and encloses it for aesthetic purposes.

Simply get any USB cable and cut it with scissors. Strip the main black insulation to reveal the cables within. If you have a data USB cable, it will have 4 wires. If you have just a power USB, it will have 2 wires. In either case, locate the red and black wires, and strip them with wire strippers or scissors. Make sure the wires do not touch, and have a decent amount of metal poking out. The finished product should look similar to the image. After you have finished, set this aside.

Image Credit: Gringo Gadgets

This step can be rather difficult to understand, as AUX cables come in many types and standards. First, get a STEREO 3.5mm Aux cable. Most Aux cables are stereo, as not many mono cables exist anymore. You can verify this by checking how many bands are on the jack. The bands are the little black rings dividing the metal. If there are two rings, Good Job! There should also be only 3 strips of metal on the cable: the tip, ring, and sleeve. When stripping the cable using the same process as the USB cable, you may come across 3 or 4 cables within the main insulation. 3 of them will be used for the speakers, the fourth will not, as it is the microphone cable.

Unfortunately, there is no color coding standard for the wires inside an Aux cable, so you can either finish the amplifier and perform trial and error, or use a multimeter's Continuity feature to check which wire is which. If using a multimeter, touch one tester probe to either the tip, ring, or sleeve of the auxiliary cable, and touch the other probe to one of the three (or four) wires. When continuity is detected, write down which is which. (eg. Tip = purple wire) If you have four wires, and one of them makes no connection, it is the mic cable, and you can snip it off with scissors.

If you 3D printed the enclosure for the amplifier, place the PAM8403 board in the enclosure. Next, take the stripped USB cable. Route the red and black cables through the holes in the amplifier. Solder the red Cable to the (+) terminal next to 5V on the Amp Board. Next, do the same with the black cable, except it goes to (-) next to 5V.

Next, take the stripped AUX cable. Use the chart below to identify which wire goes where.

1. Tip (T): Carries the left audio channel signal.
2. Ring (R): Carries the right audio channel signal.
3. Sleeve (S): Serves as the ground connection for both audio channels.

eg, if you marked "tip = purple wire," then keep in mind that the purple wire is the left audio channel.

The board will have signs next to 3 terminals that are labeled L, ┴, and R. Solder the Left Audio Channel to L, the Right Audio Channel to R, and the Ground Connection to ┴. Remember to route the Aux cable through the enclosure's hole!

On the opposite side of the PAM8403 board, there will be labels L and R next to OUT with their respective (+) and (-) terminals. Solder a long piece of red wire to the (+) terminals of both L and R. Now solder a long black piece of wire to the (-) terminals of both L and R. Remember to route the cables through the enclosure's holes!

Plug the red and black wires from L into your Left speaker's red and black terminals, and do the same for the Right speaker. Push the cap onto the enclosure to secure it. Next, plug the USB cable into a Power Source, such as a USB Wall Adapter or a Power Bank. Then, plug the AUX cable into your PC or audio device, such as an Apple iPod. Play this YouTube video to test your speakers. [https://www.youtube.com/shorts/d_Rsn-pO86A] (This is not my channel, but I always use this video to test my speakers.)

If one of the speakers is not working, try stripping or moving the red or black cables feeding into it. If they still don't work, try resoldering the wires next to OUT on the PAM8403 board. If that doesn't work, then you might have soldered the wrong wires onto the L, ┴, and R.

1. When installing the speakers into your PC, do NOT plug in the USB cable for the PAM8403 board into the PC. This makes a ground loop and will cause your speakers to stutter, squeak, or play static.

1. If your USB cable is too short, and you need to plug it into the PC for whatever reason, consider purchasing a ground loop isolator from Amazon, and it will fix the issue.

1. For even better sound, consider getting a USB DAC (digital-to-analog converter), which will provide improved sound quality while also minimizing ground loop interference.

1. Keep the Amplifier away from heat sources, direct sunlight, or coverings.