Coaxial and Optical Digital Audio Cables Differences

Your Equipment Determines Which to Use

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

Coaxial and optical cables are used to make audio connections between a source such as a CD or DVD player, turntable or 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. In the interest of making it possible for you to make informed decisions, here are 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 (electromagnetic interference). If there are any existing 'hum' or 'buzz' problems 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 – 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 and not electricity carries the information. 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 and appreciable only with higher-end systems, if 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.