What You Should Know About the SPDIF Connection (2022 Guide)

When to Use SPDIF (Cont’d)

Most home theater receivers have an integrated video switcher. This allows you to connect all sources of audio and video you have at home (cable/satellite box, Blu-Ray player, DVD player, video game console, computer, etc.) to the audio receiver, and the audio and video to be changed from one source to another by just pressing one button or turning a knob. So, instead of having all cables being connected to the TV, they are all connected to your home theater receiver, making it necessary to have only one HDMI cable carrying the video from the receiver to the TV.

Some home theater receivers are able to extract the digital audio from the HDMI connectors from all your audio/video sources. So, you only need to use HDMI cables. See Figure 3 to understand this scenario.

Figure 3: Audio receiver with an integrated video switcher and able to extract digital audio

If your home theater receiver isn’t able to extract audio from the HDMI connectors, then you will be required to use SPDIF cables to carry the digital audio. There are two possible configurations for this scenario. The most common is shown in Figure 4. Instead of having only one cable from each audio/video source, we will now have two: the HDMI cable, carrying the video signal, and the SPDIF cable, carrying the audio signal.

In the case of computers, if you want to connect only audio, but not video, you can use the connection shown in Figure 4 without using the HDMI connection shown.

The second possibility must be used if your audio receiver doesn’t have a video switcher. In this case, all your audio/video sources are connected directly to the TV, and assuming that your TV is able to extract audio from its HDMI inputs and route it to its SPDIF output, you will use this SPDIF output to connect the TV to the audio receiver. Equipments that only generate audio (e.g., CD players, MiniDisc decks, etc.) must be connected directly to the audio receiver. In this case, the selection of which equipment is going to be used will be done on the TV, not on the audio receiver.

There are two kinds of consumer-level SPDIF connections, coaxial and optical. The coaxial connection uses a mono RCA connector, usually painted orange, to make it easier to differentiate it from video connections that use a similar connector. The optical connection uses a square connector called Toslink (Toshiba Link). Some equipment has both connectors; some have only one of them. Let’s see some examples.

In Figure 6, we have the back of a professional-grade CD player (Pioneer CDJ-100S), which has a coaxial SPDIF output. Note how it has a switch for you to enable this output. The other connectors are the analog audio outputs and a jack for an optional remote control.

Figure 6: Example of a coaxial SPDIF output

In Figure 7, we see the back of a DVD player, which has both the optical and the coaxial SPDIF outputs.

Figure 7: Example of optical and coaxial SPDIF outputs

In Figure 8, we have the back of a video game console, which has an optical SPDIF output as well as an HDMI output.

Figure 8: Example of optical SPDIF output

In Figure 9, we have the back of an audio receiver, featuring an optical SPDIF input and a coaxial SPDIF input. See how, on this particular receiver, the optical SPDIF input is labeled “Video 2 In,” and the coaxial SPDIF input is labeled “DVD In.” This is important information because these are the names the equipment uses for these inputs.

The coaxial SPDIF cable is a simple mono RCA cable. See Figure 10. The optical SPDIF cable is a fiber optics. There are two kinds of optical connector. The most common is a square one (see Figure 11), but a 3.5 mm optical connector is also available (see connector on the right-hand side in Figure 12). This 3.5 mm connector has the same size as a 3.5 mm headphone plug and is commonly used on laptop computers. There are also adapters for you to convert the regular square connector into a 3.5 mm one.

Figure 10: Coaxial SPDIF cable

Figure 11: Optical SPDIF cable

The availability of ready-to-use SPDIF connectors will depend on the motherboard or laptop model. Looking at the rear panel of your computer, you can easily see if your computer has optical and/or coaxial SPDIF connectors. The motherboard shown in Figure 13 comes with an optical SPDIF connector, while the motherboard shown in Figure 14 comes with both optical and coaxial SPDIF connectors.

On laptops, the presence of an SPDIF output is more difficult to detect, because it is usually combined with the headphone jack, supporting the 3.5 mm optical connector (see previous page). Therefore, most users think that they don’t have an SPDIF output on their laptops, while this feature may be available. You have to take a look around the headphone jack to see if the word “SPDIF” is written near it, as it is the case with the laptop portrayed in Figure 15. Several laptop models, however, won’t bring any indication that they have an SPDIF output. You will have to check on the product specifications page to see if SPDIF is listed. If it is, then the headphone jack is also an SPDIF output.

There are other tricks to detect the support for SPDIF. You can try using your computer in the dark and playing a song with it to see if you can see a red light coming out of the headphone jack, indicating that there is an SPDIF interface inside. (Don’t look directly at the source of the light; it can damage your eyes.) Another trick is to see the color of the jack. If it is just green, probably the jack doesn’t have SPDIF function, but if it is black, like the jack shown in Figure 15, it probably does. Unfortunately, not all manufacturers follow this scheme.

Last update on 2022-12-03 at 14:46 / Affiliate links / Images from Amazon Product Advertising API