Whether you’re connecting a music streamer to an external digital to analogue converter (DAC) or improving your music listening experience, understanding what an audio coaxial cable is and how it works can help you make an informed purchasing decision.

In this short guide, I go through the technology and different types of audio coaxial cable and connectors that are available for consumer audio electronics.

What is an audio coaxial cable?

A coaxial cable is used to transmit digital audio signals between devices. Unlike analog cables that carry electrical audio signals directly, coaxial cables carry digital signals. This means they transmit audio data in a digital format (S/PDIF to be precise), resulting in clearer, more precise sound.

How do coaxial audio cables work?

Coaxial audio cables consist of a central conductor, an insulating layer, a metallic shield, and an outer insulating layer. The central conductor carries the audio signal, while the metallic shield helps to protect the signal from electromagnetic interference (EMI), ensuring a high-quality transmission.

While digital coaxial cables may look exactly the same as RCA phono cables that are used for transmitting analogue audio signals, coaxial cable must conform to a 50, 52, 75, or 93 Ω (ohms) impedance to meet standards. The accepted impedance for consumer audio applications is 75 ohms.

What about Toslink optical cables, aren’t they better?

Not in my experience. Comparing similarly priced optical and coaxial digital cables, I have found that coaxial cables sound fuller, better tonally balanced and specifically, less bright. If your system needs a bit of extra sparkle, then an optical cable might be for you.

Many devices only come with optical connections. For example, it’s common that televisions only provide an optical out for connecting to an external soundbar or stereo system. If optical is your only option, then try to spend more on a cable made from glass. If you are connecting to a cheap external soundbar, an optical cable made from plastic might be sufficient.

If you have the option, coaxial cables are usually the recommend choice of audiophiles for best sound quality. But at the end of the day, it’s impossible to make a hard and fast recommendation because there are so many factors involved; not least the sending and receiving equipment and how well the interfaces are implemented.

Types of connectors

Coaxial cables for audio typically use RCA connectors. These connectors are color-coded (usually orange) to differentiate them from other types of RCA cables. The RCA connectors are robust and ensure a stable and secure connection. Another common connector associated with coaxial audio cables is the BNC connector, which is more often used in professional and high-end audio equipment due to its secure locking mechanism.

Importance of quality

When choosing an audio coaxial cable, quality is paramount. High-quality cables ensure that the digital audio signal is transmitted without loss or degradation. Look for cables with gold-plated connectors, as gold is a good conductor and resistant to corrosion. The shielding quality is also crucial; double or triple shielding can provide better protection against interference.

Price considerations

Audio coaxial cables come in a range of prices. While it might be tempting to go for the cheapest option, investing in a higher-quality cable can make a significant difference in audio performance. Budget cables might lack adequate shielding or use substandard materials, leading to signal loss or interference.

Mid-range to high-end cables, priced between $20 to $50, typically offer better construction and performance. However, ultra-premium cables may not provide noticeable improvements for most users compared to mid-range options.

A good entry-level coaxial cable that I personally recommend is the Chord Company C-Digital Coaxial cable. Using Chord’s digital array technology from it’s more expensive offerings, this cable will be a significant step up from cheap variants.

The SPDIF protocol

The S/PDIF (Sony/Philips Digital Interface Format) protocol is used to transmit digital signals between devices using coaxial cables and optical cables. This protocol is used for transmitting digital audio signals and it is a standard feature in many audio devices, including CD players, DVD players, music streamers (like the Bluesound Node 2021), and home theater systems. SPDIF can transmit high-quality audio signals and it is designed to minimize signal degradation and jitter, ensuring a clear and accurate sound output.

Making a purchase decision

When purchasing an audio coaxial cable, consider the following factors:

1. Length: Choose a cable length that suits your setup without being excessively long. Excess length can lead to signal degradation and clutter.
2. Build Quality: Look for cables with sturdy connectors and good insulation. Gold-plated connectors and double or triple shielding are indicators of higher quality.
3. Brand Reputation: Opt for reputable brands known for their audio accessories. Reading reviews and seeking recommendations can guide you towards reliable products.
4. Compatibility: Ensure that the cable is compatible with your devices. Most modern audio equipment with digital audio outputs and inputs will support coaxial cables, but it’s always good to check.
5. Budget: While it’s wise to avoid the cheapest options, there’s no need to overspend. Mid-range cables often provide a good balance of price and performance.

Conclusion

A good quality audio coaxial cable is an essential component for anyone looking to achieve high-quality digital audio transmission. Understanding the nuances of connectors, quality, pricing, and the S/PDIF protocol will help you make an informed decision.

Whether you’re setting up a simple audio system or a sophisticated home theater, choosing the right coaxial cable can significantly enhance your listening experience. Investing in a good quality cable ensures that you get the best possible sound from your audio equipment.

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