No Sound from TV Optical Output: Fix PCM and Edifier Speaker Inputs

The TV picture is fine. The optical cable has a red light. Bluetooth music works on the speakers, yet a film is silent. The likely fault is not necessarily a damaged speaker: the TV may be sending an audio format that this input cannot decode.

This guide uses the Edifier R1280DBs as a concrete example. Other speakers can have different inputs and decoder support, so apply the signal-path method while checking the exact model.

Follow the Audio Through Three Separate Stages

The TV must send a supported signal, the active speaker must listen to the matching input, and the second speaker must receive its wired connection from the active unit. A failure at any stage can produce silence.

Set a Compatible PCM Output on the TV

Look for the TV’s digital audio output or audio-format setting. Choose the supported stereo PCM option for this speaker pair rather than assuming that Auto, Pass-through, Dolby Digital or DTS will work.

The R1280DBs optical and coaxial inputs accept PCM at 44.1 or 48 kHz. They are not a general-purpose decoder for every surround-sound bitstream a TV or streaming box can send. A menu showing “optical connected” does not settle the format question.

Test with a familiar TV programme or app after making the change. If that works but an HDMI-connected player remains silent, check that player’s audio output and the TV’s handling of that input. The external source may still be delivering a different format.

Menu names vary by TV and software version. The aim is a compatible stereo PCM signal at the optical output, not finding one universal sequence of buttons. Record the original setting so you can compare the result and restore it if necessary.

Select Optical on the Speakers

Use the OPT selection on the R1280DBs remote, or the input selector on the active speaker. The manual’s indicator is red for optical and coaxial operation, so a red light alone does not distinguish those two inputs. Make the selection deliberately.

Check that the optical cable is in the socket marked Optical, not a different digital or analogue connector. Coaxial digital uses a different physical cable and input. An RCA line input is analogue even though the connector shape can resemble other RCA connections.

1. Turn on the speaker pair and confirm its mains connection.
2. Select Optical explicitly.
3. Make sure the speakers are not muted, then set a modest listening level.
4. Start a TV source known to be playing audio and confirm the TV is using its intended external audio output.
5. Change one setting at a time and listen again.

If a TV remote does not adjust the external-speaker volume, do not treat that behaviour alone as proof of an audio failure. Optical is a different connection from HDMI ARC or eARC. Volume-control behaviour depends on the TV and the audio arrangement; the Edifier remote and speaker controls remain useful for this test.

Check the Cable and Both Speakers

Remove protective caps from a new optical lead, align the connector correctly and seat it fully without forcing it. Avoid sharp bends or trapping it behind the furniture. Inspect the cable and sockets rather than repeatedly pushing an incorrectly oriented plug.

A visible red light can help identify a live optical path, but it cannot tell you which codec is being sent. Do not look directly into an optical port. If another suitable cable is available, substitute only the cable while keeping the working format and input settings unchanged.

The R1280DBs pair has an active speaker and a wired passive partner. If only one side plays across different sources, switch off the speakers and check the supplied interconnect at both ends, including secure terminals and stray strands. Follow the manual’s polarity and connection diagram.

Do not connect an amplified speaker output to a line-level input to experiment. The correct connection is determined by the labels and the manual, not by whether two plugs can be made to fit.

Use Another Source to Isolate the Fault

Play a familiar recording from a phone over Bluetooth, or use a suitable analogue source and the matching line input. This is an isolation test, not a promise that different sources will have identical volume.

If the pair works from that source, return to the optical path with PCM selected. If it remains silent on every input, check power, mute, volume and the source connection before blaming the TV’s digital format.

For a desk-call problem rather than TV playback, the small-room speakerphone setup guide addresses a different signal path: microphones, meeting software and echo management.

Finish with a Working TV-Audio Check

Test the sources you actually use: a TV app, broadcast audio and any external HDMI player. Confirm both speakers play, speech is clear, and you can control volume using the chosen arrangement. A test of just one app can miss a source-specific format problem.

The useful order is format, input, cable, then the speaker pair. Set compatible stereo PCM, select Optical explicitly, inspect the lead and verify both channels. Replace hardware only after those checks show where the signal stops.

Frequently Asked Questions