Coaxial and Optical Digital Audio Cables Differences

Your equipment dictates which to use

Fiber optic audio cable

Hustvedt/Wikimedia Commons/CC BY-SA 3.0

Coaxial and optical cables are used to make audio connections between a source such as a CD or DVD player, turntable, or other media player, and another component such as an amplifier, receiver, or speaker. Both cable types transfer a digital signal from one component to the other.

If you have the opportunity to use either type of cable, you might be curious about the unique characteristics of each and which is the better choice for your purpose. The answer can vary depending on who you ask, but many people agree that the differences in performance are usually negligible. To help you make informed decisions, here are facts about coaxial and optical digital cable connections.

Coaxial digital audio cables

A coaxial (or coax) cable is a shielded copper wire, generally manufactured to be quite rugged. It is a single wire which can transfer a signal, unlike other wired components such as speakers. Coaxial cables also do not require being connected in a specific orientation; they simply plug in one way. Each end of a coaxial cable uses familiar RCA jacks, which are reliable and stay firmly connected. However, coaxial cables may be susceptible to RFI (radio frequency interference) or EMI (electromagnetic interference). If there are any existing hum or buzz sound problem within a system, such as a ground loop, a coaxial cable may transfer that noise between components. Coaxial cables are known to lose signal strength over long distances, which is usually not a concern for the average home user.

Optical digital audio cables

An optical cable (also known as Toslink) transfers audio signals via red light beamed through a glass or plastic fiber optic medium. The signal that travels through the cable from the source must first be converted from an electrical signal to an optical one. When the signal reaches the receiver, it undergoes a conversion back to an electrical signal again. Unlike coax, optical cables are not susceptible to RFI or EMI noise or signal loss over distances, because light does not suffer from the resistance and attenuation that occurs in copper cables.

However, optical cables tend to be more fragile than their coax counterparts, so care must be taken to ensure they are not pinched or bent tightly. 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.

Your choice

The decision about which cable to purchase will most likely be based on the type of connections available on the electronics in question. Not all audio components can use both optical and coaxial cables.

Some users argue a preference of coaxial over optical, due to a presumed improvement of overall sound quality. While such subjective differences may exist, the effect is likely subtle, notable only with high-end systems, if even that. As long as the cables themselves are well-made, you should find little performance difference between the two types, especially over short connection distances.