Soundbar Optical Input Limitations

What an optical connection can carry

An optical audio input (also called Toslink) uses a fiber optic cable to transmit digital audio signals. It is a common connection on soundbars and TVs. The optical standard (S/PDIF) has a fixed bandwidth that limits the types of audio it can carry.

Optical can carry two-channel uncompressed PCM (stereo) and compressed multi-channel formats such as Dolby Digital (up to 5.1 channels) and DTS (up to 5.1 channels). Many TV broadcasts, streaming apps, and DVDs use these compressed formats, so optical works well for those sources.

When you see a soundbar listing that mentions an optical input, it means the soundbar can accept these standard digital audio signals from your TV or other source device. For a simple setup, a budget soundbar with optical may be all you need.

What optical cannot carry

The main limitation of optical is its bandwidth. It cannot carry lossless audio formats that require higher data rates. These include Dolby TrueHD, DTS-HD Master Audio, and multichannel PCM beyond two channels (such as 5.1 or 7.1 PCM).

Optical also cannot carry Dolby Atmos metadata when the source is a Blu-ray disc. While some streaming services deliver Atmos via Dolby Digital Plus (which optical can handle), the full Atmos experience from Blu-ray requires Dolby TrueHD, which optical cannot transmit. If you want Atmos, look at the best Dolby Atmos soundbars.

Additionally, optical does not support high sample rates above 96 kHz or high bit depths beyond 24-bit. If you want to play high-resolution audio from a Blu-ray player or game console, optical will not deliver the full signal.

The connection also lacks the two-way communication that HDMI provides. Optical is a one-way link from source to soundbar, so it cannot support features like Audio Return Channel (ARC) or CEC control. For that, you need HDMI ARC or eARC.

When to use HDMI instead

HDMI ARC (Audio Return Channel) and HDMI eARC (enhanced Audio Return Channel) can carry all the formats that optical cannot. HDMI eARC supports lossless formats like Dolby TrueHD, DTS-HD Master Audio, and multichannel PCM up to 7.1. It also carries Dolby Atmos metadata from Blu-ray sources.

According to the HDMI specification, eARC simplifies connectivity and supports the most advanced audio formats and highest audio quality. It ensures full compatibility between audio devices and upcoming HDMI products.

If you want to enjoy Dolby Atmos from Blu-ray discs or lossless surround sound from game consoles, you need a soundbar with HDMI eARC and a TV that also supports eARC. For standard compressed surround sound, optical may be sufficient.

Check your soundbar listing for HDMI ARC or eARC. If the listing does not mention HDMI, the soundbar likely relies on optical or other connections for digital audio. For a premium setup, consider the best premium soundbars.

How to check your TV and soundbar connections

Before buying a soundbar, look at the ports on your TV. If your TV has an HDMI ARC or eARC port, you can use that for the best audio quality. If your TV only has an optical output, you will be limited to the formats optical can carry.

On the soundbar listing, check the connection section. It will state whether the soundbar has HDMI ARC, HDMI eARC, optical input, or both. Some soundbars include both, giving you flexibility.

If you plan to connect external devices like a Blu-ray player or game console directly to the soundbar, HDMI inputs on the soundbar are necessary for lossless audio. Optical cannot carry those formats from the source. Learn more about soundbar connectivity options.

When optical is still useful

Optical remains a reliable connection for many setups. If you only watch TV broadcasts, stream movies from services that use Dolby Digital Plus, or play games on a console that outputs compressed audio, optical will work fine.

Optical cables are inexpensive and widely available. They are also immune to electrical interference, which can be an advantage over analog connections.

For a second TV in a bedroom or a simple setup where you do not need lossless audio, a soundbar with an optical input can be a good choice. Check the soundbar's listing for the optical input and confirm it matches your TV's output. You might also compare optical and coaxial for your needs.

Comparing optical and HDMI for your setup

When choosing between optical and HDMI, consider what you watch and how you watch it. For standard TV and streaming, optical is fine. For Blu-ray movies with Dolby Atmos or DTS:X, HDMI eARC is necessary.

If you have a gaming console, HDMI eARC can carry uncompressed 5.1 or 7.1 PCM, which optical cannot. For gaming, you may also want HDMI 2.1 gaming features.

Some soundbars offer both optical and HDMI inputs. In that case, you can use HDMI for your main source and optical for a secondary device like an older DVD player. This gives you flexibility without sacrificing quality.

What to pick for your situation

Questions

Can optical carry Dolby Atmos?

Optical can carry Dolby Digital Plus, which some streaming services use to deliver Atmos metadata. However, optical cannot carry the lossless Dolby TrueHD format that Blu-ray discs use for Atmos. For full Atmos from Blu-ray, you need HDMI eARC.

Is optical better than HDMI for audio quality?

No. HDMI ARC and eARC can carry higher bandwidth audio formats, including lossless surround sound. Optical is limited to compressed formats and stereo PCM. For the best audio quality, use HDMI. Compare HDMI ARC vs optical.

Do all soundbars have an optical input?

No. Many soundbars include an optical input, but some budget models may omit it. Check the listing's connection section to see if optical is listed.

Can I use optical with a 4K TV?

Yes. Optical is a separate audio connection and does not affect video. You can use optical for audio while HDMI carries video to the TV.

Does optical support 5.1 surround sound?

Yes, optical supports compressed 5.1 formats like Dolby Digital and DTS. It does not support uncompressed 5.1 PCM.

What is the maximum sample rate for optical?

Optical (S/PDIF) typically supports up to 96 kHz sample rate and 24-bit depth. Higher sample rates like 192 kHz are not supported.

Can I connect a soundbar to a TV with only an optical cable?

Yes, if both the TV and soundbar have optical ports. You will get stereo or compressed surround sound depending on the source.

Does optical support DTS:X?

No. DTS:X is a lossless format that requires HDMI eARC. Optical cannot carry it.