Introduction: Switchbox for Digital Audio

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Check out the author’s website, Neat Information.com, for lots of interesting articles.

Most current home electronics have SPDIF digital coax (RCA jack) or optical (TOSLink) outputs or both. Digital coax jacks are far more common, even appearing in bargain basement DVD players. Most home theater systems have both digital coax and optical inputs.

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 and cables. This tutorial describes how to manually select different digital coax (RCA) sources.

Technically you should use 75 ohm shielded cable, but in my experience standard RCA-RCA cables work fine for at least 4 meters (the distance from my computer to my home theater system box).

Step 1: Switch It!

Picture of Switch It!

The good news is you can also use an inexpensive manual video switchbox to select digital audio inputs.

Just hook up an RCA-RCA cable from the switch box’s output to the home theater system’s input. Then hook up each of your electronics with digital outputs to the switchbox’s inputs. Use the same color jack for each jack on the switch box (i.e. all yellow).

I use my switch box to select digital audio from my cable television box, primary computer’s built-in audio and Blu-Ray player. Any digital audio source with a RCA SPDIF output can be used.

The added dimensions for 5.1 sound from the home theater system really make a difference for action movies and concerts.

My cable provider has a couple of dozen digital audio channels. By sending the digital audio directly to the home theater I don't have to waste electricity by powering on the television set just to listen to audio.

Step 2: Hook Up Cables

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While it’s desirable to use orange color-coded cables to avoid confusion it’s not absolutely necessary. I’ve used colored-plastic tape and colored loose leaf labels to help identify cables.

Step 3: Add a Digital Sound Port If Necessary

Picture of Add a Digital Sound Port If Necessary


If your computer doesn’t already have a digital output jack there may already be an existing circuit on your motherboard that just needs a connector, or you can add a sound card which does have digital audio out.

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