Home theater audio has come a long way. Surround sound used to mean a basic 5.1 setup with compressed audio. But modern systems can play lossless, object-based sound formats like Dolby Atmos for lifelike immersion. To enable these advanced audio codecs, you need the right connection between your TV and sound system.
The two most common options for TV audio output are HDMI eARC and optical. Both have benefits that make them suitable in different scenarios. In this guide, we‘ll do a deep dive on eARC vs. optical to help you upgrade your home theater‘s sound.
Overview of eARC and Optical Audio
eARC stands for Enhanced Audio Return Channel. It builds on the standard ARC technology to add support for high-bitrate audio formats. eARC uses the HDMI cable to transmit both audio and video.
Optical is a digital audio connection that uses fiber optic cables. Also called TOSLINK or SPDIF, optical has been used for decades to connect TVs and audio components.
Our goal is to analyze the key differences between these two methods. We‘ll compare technical specifications, audio quality, cables, compatibility and more. Read on to learn which connection is best suited for your home theater needs.
Diving into the Specs: eARC vs. Optical
Let‘s start by looking at the technical capabilities of each connection type. This will help explain why eARC can transmit more advanced surround sound than optical.
Bandwidth
One of the biggest differences is bandwidth, which determines how much data can be transferred per second.
eARC supports up to 37 Mbps of uncompressed audio bandwidth. This allows it to handle high-resolution surround sound formats [1].
Optical connections are limited to around 5 Mbps maximum bandwidth. This is sufficient for basic compressed audio, but too low for lossless formats [2].
Audio Codecs
eARC can transmit virtually any surround sound format, including:
- Dolby TrueHD
- Dolby Atmos
- DTS:X
- DTS-HD Master Audio
These advanced codecs use lossless audio and object-based mixing for the best quality.
Optical is limited to standard Dolby Digital and DTS. These are compressed, or "lossy" audio formats that sacrifice fidelity for smaller file sizes.
Here is a comparison of selected audio formats supported over eARC vs. optical:
| Format | eARC | Optical |
|---|---|---|
| Dolby Digital | ✅ | ✅ |
| Dolby Digital Plus | ✅ | ✅ |
| Dolby TrueHD | ✅ | ❌ |
| Dolby Atmos | ✅ | ❌ |
| DTS | ✅ | ✅ |
| DTS-HD Master Audio | ✅ | ❌ |
| DTS:X | ✅ | ❌ |
Audio Channels
eARC supports up to 32 discrete audio channels compared to 8 channels for optical [3].
This enables larger, more immersive speaker configurations. An advanced 7.1.4 Dolby Atmos setup with height speakers requires at least 11 channels, for example.
Cables
eARC requires an HDMI cable with plenty of bandwidth – at least 18 Gbps. Many newer cables are 48 Gbps compatible. Always use a certified Premium High Speed HDMI cable.
Optical audio connections just need any standard TOSLINK optical cable. These are much cheaper than high-bandwidth HDMI.
Connector Types
The eARC connection uses the standard HDMI type A port. Optical connectors are square TOSLINK ports. Look for ports labeled eARC, ARC, or optical audio in/out.
So in summary, eARC provides far more bandwidth and support for advanced surround sound formats compared to the aging optical standard. But optical remains a cheap and widely compatible option.
Real-World Home Theater Examples
How do these technical differences play out in real home theater setups? Here are a few examples where eARC or optical make the most sense:
Basic Soundbar
You want to add better sound to your existing TV with a soundbar like the Sonos Beam. Since the Sonos Beam doesn‘t support Dolby Atmos or other advanced codecs, optical is generally sufficient here. An optical cable will provide the compressed 5.1 Dolby Digital soundbar signal.
Using eARC would provide no benefit, unless you also want to use HDMI-CEC features. Optical keeps costs down for basic soundbar usage.
HTIB Surround System
Connecting a Home Theater in a Box (HTIB) system like the Vizio S4251w-B4 to your TV also doesn‘t require eARC. Systems like this are meant for basic 5.1 surround sound rather than object-based audio. You can use an inexpensive optical cable without losing out on audio formats.
Dolby Atmos Soundbar
If you upgrade to a soundbar with Dolby Atmos like the Sonos Arc, then eARC starts to make sense. Atmos soundbars can decode advanced object-based audio sent over eARC. An optical connection would be limited to standard Dolby Digital and you‘d lose Atmos support.
A/V Receiver + Speakers
For a high-end home theater with an AV receiver and surround sound speakers, eARC is definitely the way to go. You‘ll be able to send Dolby TrueHD, DTS-HD MA and other lossless codecs from your TV apps over eARC for the best audio quality. Using optical would bottleneck your audio to compressed 5.1 at best.
As these examples illustrate, choose optical for basic setups or eARC for advanced Atmos/DTS:X support.
eARC vs. Optical: Compatibility Considerations
One downside of eARC is compatibility – your devices must support the new standard to work. Optical has near universal compatibility.
Here are some tips to ensure compatibility:
- Confirm your TV, soundbar/receiver, and cables are rated for the HDMI 2.1 spec and eARC
- Some devices need firmware updates to enable eARC capabilities
- Use a certified 48 Gbps HDMI cable for flawless eARC support
- Trying toggling eARC settings Off and Auto on the TV input
- Optical is compatible with basically any TV or audio device with the port
See your equipment‘s specs and manuals to double check eARC compatibility. Optical will work in most cases.
Audio Quality Comparison
In terms of audio quality, eARC capable systems simply sound better than optical when playing advanced surround formats. The lossless reproduction provides noticeably better clarity and spatial imaging.
However, both connections will sound identical when limited to basic Dolby Digital 5.1 audio. You need equipment that takes advantage of the higher-resolution eARC formats to hear a difference.
Overall, while optical sounds decent for basic surround sound, eARC delivers a more detailed, theater-like listening experience.
Troubleshooting Tips
Here are some handy tips for avoiding issues with both eARC and optical:
- Update TV, A/V receiver, and soundbar firmware for latest eARC patches
- For eARC, enable CEC device control options on both TV and audio device
- Try different HDMI ports and cables if eARC isn‘t working
- Reseat optical connections firmly and check for any bent pins
- Ensure TV output is set to Bitstream or Auto (not PCM)
- Set audio system eARC input as the default if sound cuts out
- Test cables to eliminate any defects or damage
Take your time with setup, and don‘t force any connections. Following this guide and the included tips will help you successfully implement either audio option.
After comparing eARC vs. optical connectors for home theater use, eARC is the clear winner in most cases. It supports virtually every surround sound format and delivers theater-quality audio.
However, optical remains a reliable standard for basic setups. And it‘s the only choice when dealing with older HDMI-less gear. Not everyone needs or wants an elaborate Atmos setup anyway.
The most important thing is choosing the connection that makes sense for your equipment and listening preferences. An $80 soundbar will perform just fine with a $5 optical cable. But unlocking the full potential of premium home theater gear requires eARC connectivity.
