The Truth Behind Which Is Better — Optical vs. RCA

optical vs rca

Whether you’re assembling your first surround-sound setup for your home entertainment system or wish to give it an upgrade in the form of speakers, stereos, subwoofers, base, soundbars, and a sound interface, you should mind your cabling and sound plug formats. You should be aware of your options. At present, you have HDMI, optical, coaxial, and RCA cable options. RCA is the oldest, optical and coaxial deliver the same quality, and HDMI is the best of the bunch in terms of compressed or uncompressed HD audio.

For the purposes of this article, we will discuss which one is better—optical vs RCA. HDMI is superior to both, but if you were to choose between only them for various reasons, then keep on reading. 

RCA and Optical Debate for Speakers and Sound Systems

  • Optical/TOSLINK: The optical port format, also known as TOSLINK or Toslink, is the format that transmits signals to glass tubes, fiber optics, and light. Specifically, TOSLINK uses fiber-optic cables that transfer information through the light that’s beamed through glass or plastic fiber optic tubes. This is the reason why when a kink on an optical cable happens, the whole cable is usually ruined or there’s significant attenuation.

Optical cables are becoming less and less common due to how commonplace and cheaper HDMI cables have become. Their light-pulse transmission medium through hollow channels on the middle of the cable allows minimal signal degradation. However, it’s limited to transferring only 5.1 surround sound. The format itself is known as the ADAT protocol and the cables make use of fiber-optic tech, hence them being referred to as optical cables.

  • RCA: Your parents or grandparents probably used RCA cables. RCA is an analog connection that’s able to provide surround sound through multiple connections. This fact is also the reason why they remain relevant in today’s HDMI-dominated world of electronics. Not everyone has shifted to HD sound and have legacy speakers and stereos that work perfectly fine with their RCA rigs. They were originally developed for the transfer of analog sound and music. This means they have limitations when it comes to delivering digital recordings.

They sound fine with analog recordings but certain nuances found in crystal-clear digital recordings will tend to suffer a measure of degradation. It’s because of this that unless you’re using an older analogy system you should shift to optical or HDMI. At any rate, depending on your home theater in a box surround sound system, you might need to connect your speakers to a receiver with an included speaker wire that might be RCA or optical instead.

  • Similarities and Differences: At present, HDMI cables are more of an HDTV kind of deal than something you’d use for your speakers unless you’re using the really high-end HDMI speakers and sound interfaces for your Blu-Ray or DVD player needs. You’re likelier to encounter an optical cable or digital coax to connect sound electronics like a subwoofer to your receiver. At most, you’ll need your HDMI cable for your projector or HDTV. Rarely do you use a spare cable for sound connections? 

Digital coaxial cables have RCA connectors by the way. However, they shouldn’t be confused with RCA cables on the old analog RCA format because that format has the aforementioned degradation problems when listening to digital recordings that you won’t hear when using either optical or digital cables. With that said, optical cables tend to have major issues due to kinks and bends compared to coax or even old-timey RCA. By the way, the SPDIF format allows you to connect optical or coaxial cables to it with the cost of only being in stereo versus the 8-channel capabilities of ADAT and Toslink. 

  • Pros and Cons of Both: The main problems with RCA aside from being analog and its inability to produce high-fidelity sound from digital recordings is that it has trouble with induced noise. One of the sources of such noise is a ground loop or when grounds on different pieces of equipment are connected, leading to a loop. Digital coax is less sensitive to ground loops but they’re susceptible to electromagnetic interference or radio frequency interference. Optical and digital coax are similar to each other in sound quality.

Most people won’t really notice the difference, to be honest. There’s referencing happening between two networks when using an RCA port and cable connection. With optical, the networks have what’s known as galvanic isolation. Therefore, there might be fewer issues with ground loops from optical, allowing for the networks to remain isolated and the resulting sound to have less attenuation when all is said and done. This also results in grounds not being able to act like an antenna that creates that “warm” noise sound associated with degraded RCA connections. 

  • What’s The Bottom Line? RCA is supposed to be worse than digital from channel limits to other subtle changes. However, the biggest reason to switch to optical or coax is that it’s cheaper to simply use them on most sound systems since they remain the standard. If you have a legacy system on hand from the 1990s or before that, you have no choice but to go RCA or buy a converter to be able to use them with an optical cable. 

Otherwise, you’ll likely have to choose between optical or digital coax. Also, remember that it’s a disaster to try and play your digital CD or Blu-Ray sound effects on an RCA connection unless you have a converter on hand to better translate those digital signals to something more analog, but you still lose a little something in the translation or transmission of those signals. It simply sounds different even if it’s the same song or recording.

Final Thoughts and Reminders

When buying speaker cables, you don’t need to go for the high-end option every time. There’s no requirement for you to pick from either SPDIF, optical, or coaxial formats either. You can get quality cables that are perfectly reliable for your needs at online outlets such as Amazon or eBay (as well as Craiglist if you have the time and patience to deal with buying used cables from fellow consumers like yourself).

Also, digital signals sent between devices come in an uncompressed bitstream at 44.1 kHz or 48 kHz. However, mediums like MP3 will have to be digitally converted before being sent, thus resulting in good or bad conversions by some boxes and formats. Therefore, you’ll get compressed audio regardless when listening to an MP3 Player’s MP3 songs and podcasts.


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