What's going on

When a home speaker like the Marshall Woburn III or Stanmore III refuses to play sound via HDMI, it is rarely a sign that the speaker's amplifier is dead. Marshall home speakers rely heavily on HDMI ARC (Audio Return Channel) to receive digital audio and volume control signals directly from your television.

Because HDMI ARC depends on a continuous two-way digital communication protocol called CEC (Consumer Electronics Control), a minor communication glitch on the TV's side can silence your setup instantly. Understanding whether the system suffers from digital handshake failure, incompatible TV audio bitstreams, or physical port failure is key to getting your room filling sound back.

Symptoms people notice

• Complete silence on the HDMI input: The Marshall control panel shows the HDMI indicator light lit, but no sound plays.
• CEC control loss: The TV display shows volume adjustments, but the physical output level on the speaker does not change.
• Intermittent audio cutouts: Audio works when launching a TV streaming app, but cuts out as soon as a movie starts.
• Source jumping: The speaker automatically disconnects from HDMI and reverts to Bluetooth or Aux standby.
• Garbled noise or popping: Switching channels produces a high-pitched buzz or rapid clicking noise.

Likely causes

1. Unsupported Bitstream Formats: Your TV is sending raw multichannel surround sound (Dolby Digital, DTS, Atmos) which the Marshall speaker's internal DAC cannot process. It requires PCM stereo.
2. HDMI CEC Handshake Lockup: Microcontrollers in the TV and speaker got out of sync, preventing the TV from opening the audio return channel.
3. Incompatible HDMI Cable: Standard or older HDMI cables lack the internal pin wiring necessary for ARC data transfer.
4. eARC Mode Conflict: Modern TVs with eARC ports sometimes default to full high-bitrate eARC modes that do not properly drop down to legacy ARC protocols supported by audio hardware.
5. Firmware Bug or Glitch: Outdated speaker firmware causing improper handshake responses after TV system updates.
6. Physical HDMI Port Damage: Repeated cable strain or accidental tugs bending internal port pins inside the speaker cabinet.

Quick checks first

Before taking anything apart, run through these foundational checks:

• Confirm TV Port: Ensure the HDMI cable is plugged into the specific port on your TV labeled HDMI ARC or eARC, not a generic HDMI port.
• Check TV Sound Output Menu: Verify that the TV's sound output destination is explicitly set to "Receiver (HDMI)" or "Optical/HDMI" rather than TV Speakers.
• Reseat the Connection: Unplug both ends of the HDMI cable and push them back in until you feel a firm click. Ensure the brass top panel control light stays solid on HDMI.
• Test External Sources: If you are using a streaming stick or cable box plugged into the TV, check if the issue persists across different streaming apps.

For broader speaker connectivity issues, check our guides on /problems/speakers or browse technical hardware breakdowns across different /brands/marshall devices.

When it's a real hardware fault

If you have tried multiple High-Speed HDMI cables, forced PCM output across all TV apps, and executed power-cycle resets without success, you may be dealing with a hardware-level failure.

• Loose or Broken HDMI Jack: If wiggling the cable end near the rear input panel causes audio to pop in and out, the physical port connector has desoldered from the main digital board.
• Blown HDMI CEC Receiver IC: Static electricity discharges or hot-plugging cables while equipment is turned on can fry the delicate HDMI interface board inside the speaker.
• Main Logic Board Failure: If the HDMI input LED refuses to light up at all while Bluetooth and Aux function normally, the input multiplexer chip may be damaged.

Soft resets vs board/panel work

Soft resets and software tweaks are entirely safe to perform at home. Adjusting TV output parameters, cycling CEC settings, updating speaker firmware via app, and swapping HDMI cables should always be your first course of action.

However, opening up a Marshall speaker to inspect or replace the mainboard or HDMI jack is not a recommended DIY project. Marshall home speakers are tightly sealed acoustically using heavy internal dampening, high-voltage internal power supplies, and delicate ribbon cables. Attempting board-level soldering without specialized micro-soldering tools can permanently ruin the cabinet acoustics or destroy the digital signal processor. If simple software triage fails, hardware failures are best handled by professional repair technicians or brand service centers.

Next steps

1. Set TV digital sound output to PCM in Expert Audio Settings.
2. Perform a full two-minute cold power-cycle on both the TV and speaker.
3. Swap to a fresh High-Speed HDMI cable (18Gbps+).
4. Check for firmware updates in the official Marshall app.
5. If physical port play or electrical damage is suspected, consult hardware repair resources or review alternative audio hardware at /reviews and /devices.