Introduction: Almost Free Way to Add Surround Sound to Your Computer
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The project described in this article requires basic mechanical and electronics skills and is provided for information purposes. It also helps to have a sense of humor. Do not attempt to replicate it or use it for any purpose unless you've got the proper knowledge and skills – or don’t have a sense of humor.
Your computer may already have the capabilities to generate 5.1 surround sound, even if you don’t realize it (I certainly didn’t for several months). This improvement will only work if your sound card or motherboard already has an existing SPDIF (coax digital audio out) internal connector, but doesn’t have a SPDIF jack. The project is intended for a standard desktop PC.
Check your motherboard or sound card’s documentation to see if it has a digital audio output port. Different manufacturers use different designations and connectors, anything from 2 to 4 pins.
Step 1: Parts and Setup
Spare computer bracket (free)
Two wire cable with connector salvaged from old junk computer (free)
Sticky label (cheap)
Solder and a little piece of heat shrink tubing (real cheap)
Female panel mount RCA jack (about $3).
This is the only documentation in my MSI motherboard’s manual describing the digital audio capabilities. Confusingly the two pins are labeled “2 and 3” and the commercial SPDIF connectors I’ve seen for MSI’s motherboards all have a three pin connector.
The third pin is +5 volts and only needed for the optical (TOSLink) connector. While an optical digital out connector is nice, it isn’t absolutely necessary. Most home theater systems have both digital coax (RCA jack) and optical (TOSLink) inputs and they produce the same quality audio. To add an optical TOSLink jack you need a specialized module which is more expensive, so I’d suggest only adding it if it’s absolutely necessary.
Digital coax and TOSLink use the same protocols – the only difference is whether the signal is transmitted through a wire or by light. TOSLink has the advantage of no electrical interference, but more limited distance and more expensive connectors.
Technically you should use 75 ohm shielded cable, but I’ve found standard RCA-RCA cables work fine for at least 4 meters (the distance from my computer to my home theater system box). The internal cable should be a shielded cable also, but for the relatively short distance inside a computer’s case a twisted pair cable is fine.
Step 2: Preparing the Bracket
Set your light saber to the drill mode and set the focus for a 1/4 inch diameter hole. If your light saber’s in the shop then you can use a drill.
Make a neat hole in the bracket.
SDIF Coax connectors should be color coded orange, but yellow and black are also common. Since yellow RCA jacks are also used for composite video you need to take care to ensure that they aren’t mixed up.
Place a neon orange loose leaf label neatly over the hole on the side which faces the outside of the computer. This project will not work without the label in place, in fact really bad things may happen and the Earth may implode. So make sure you put the label in place. Okay, maybe all of that won’t happen – but why take the chances?
Put the RCA connector through the hole with the jack facing the exterior. Put the grounding lug on the interior of the hole and screw the nut in place.
Switch your light saber to soldering mode.
Solder the wire from the ground pin to the ground lug on the RCA connector, and the wire from the SPDIF out to the center pin of the RCA connector. I decided to use a small piece of heat shrink tubing on the center connector to make it a bit neater. Since this is an election year you shouldn’t have any problems finding a hot air source to shrink the tubing in place.
Don’t forget to follow the proper cleaning procedure and shut your light saber off when you’re finished using it.
Step 4: Plug the Cable Into the Your Digital Sound Output
Plug the connector into the SPDIF out pins on your motherboard/sound card – ensuring that you’ve got the correct polarity, mount the bracket on the back of your computer and you’re ready to go.
You may need to go into your computer’s sound control panel to activate or unmute the SPDIF connector.
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