Coaxial and Optical Digital Audio Cables Differences

It's Your Equipment That Determines Whether to Use Coaxial or Optical Cables

A TOSLINK fiber optic audio cable being illuminated on one end
A TOSLINK fiber optic audio cable being illuminated on one end. By Hustvedt - Template:One, CC BY-SA 3.0, Link

Introduction

Coaxial and optical cables are used to make audio connections between a source (e.g. CD, DVD, turntable, media player, wireless adapter, etc.) and an amplifier, receiver, or even a speaker. Both types transfer a digital signal from one component to the other. Given the opportunity to use either one, you might be wondering about the unique characteristics of each and which may be the better choice.

Answers can vary depending on who you ask, but many tend to agree that differences in performance are typically negligible. Naturally, people prefer to make informed decisions, so here are some facts about coaxial and optical digital cable connections.

Coaxial Digital Audio Cables

A coaxial (or coax) cable is hard-wired using shielded copper wire, generally manufactured to be quite rugged. 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 (electro-magnetic interference). If there are any existing 'hum' or 'buzz' problems within a system (e.g. a ground loop), a coaxial cable may transfer that noise between components. Coaxial cables are also known to lose signal strength over very long distances – 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. And once the signal reaches the receiver, it undergoes a conversion back to an electrical signal again. Unlike coax, optical cables are not susceptible to RFI/EMI noise or signal loss over distances, because it is light and not electricity carrying the information.

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

Conclusion

The decision about which cable to purchase will most likely be based on the type(s) 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 indeed exist, the effect is likely very subtle and appreciable only with higher-end systems (if that). But as long as the cables themselves are quality-made, you should find very little performance difference between the two types, especially over short connection distances.