Coaxial vs. Optical Digital Audio Cables

Your equipment dictates which type of audio cable to use.

Coaxial and optical cables are used in home entertainment systems to connect an audio source (such as a set-top box, Blu-ray player, or video game console) to a component (such as an amplifier, audio receiver, or speaker system). Both types transfer a digital audio signal from one device to the other.

Illustration of a coaxial digital audio cable and an optical digital audio cable
Lifewire / Tim Liedtke 
  • Higher bandwidth.

  • Possible radio frequency or electromagnetic interference.

  • Sturdy connection.

  • Lower bandwidth.

  • No radio or electromagnetic frequency interference.

  • Less sturdy.

Not all audio devices support both coaxial and optical cables, so you may not have a choice. If you do have a choice, it still may not matter much. Many experts say the difference in audio quality and performance is negligible. That being said, it's a good idea to learn the basics about coaxial and optical cable connections.

Both coaxial and optical cables support 5.1 surround sound systems with a difference in sound quality that is nearly indistinguishable.

Coaxial Digital Audio Cables Pros and Cons

  • Higher bandwidth means theoretically superior sound quality, but most won't notice a difference.

  • Sturdy, harder to detach from inputs.

  • Cannot carry many high-quality lossless audio formats.

  • Possible radio frequency or electromagnetic interference.

A coaxial (coax) cable is a shielded single copper wire used in many audio interfaces and connections, although it is not quite as common as optical connections in modern sound systems. While coaxial cables promise theoretically superior sound—by means of a greater bandwidth—the difference probably isn't noticeable to most people.

Coaxial cables look and operate much like traditional RCA jacks, which are favored for their ruggedness and durability. They may be susceptible to radio frequency interference (RFI) or electromagnetic interference (EMI). If any existing humming or buzzing is present within a system, a coaxial cable may transfer that noise between components. Coaxial cables are known to lose signal strength over long distances, which is not a concern for the average home user. However, if distance is an issue, then optical cables are the better choice. Finally, coaxial cables do not have enough bandwidth to support high-end surround lossless formats like Dolby TrueHD and DTS-HD Master Audio.

Optical Digital Audio Cables Pros and Cons

  • No radio or electromagnetic frequency interference.

  • Lower bandwidth means slightly inferior sound quality, but difference probably isn't noticeable.

  • Cannot carry many high-quality lossless audio formats.

  • Less sturdy, more easily detached.

Optical or "Toslink" cables use light to transfer audio through optical fibers. Audio signals must be converted from an electrical signal to an optical one before traveling through the cable. Once the converted signal reaches the receiver, it is converted back into an electrical signal.

Optical cables tend to be more fragile than their coax counterparts; optical cables can't be pinched or bent tightly, for example. The ends of an optical cable use an odd-shaped connector that must be inserted correctly, and the connection is usually not as tight or secure as a coaxial cable's RCA jack.

Optical cables are not susceptible to RFI or EMI noise or signal loss over distances, because light does not suffer from the resistance or attenuation that occurs in copper cables.

Like coax cables, optical cables do not have enough bandwidth to carry lossless or uncompressed audio formats, such as those used on Dolby surround sound systems.

Your Choice

The decision about which cable to use should be based on what is available to you. Not all audio components can use both optical and coaxial cables, and HDMI is increasingly the standard for most home entertainment systems and components.

Some users prefer coaxial over optical because it can support slightly higher resolution audio, but those differences are likely only noticeable on very high-end sound systems, if at all. As long as the cables themselves are well made, you should find the sound they produce to be indistinguishable.

HDMI cables transfer both audio and video. If your equipment supports HDMI connections, you should use it. In addition to 3D and 4K UHD content, HDMI can support uncompressed audio format to eight channels, allowing for 7.1 surround sound.

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