Public bug reported:
## Summary
No audio output from internal speakers on ASUS ExpertBook B3404CMA
with Realtek ALC294 codec and Intel Meteor Lake-P after upgrade to
Ubuntu 26.04 LTS (Resolute Raccoon). Bluetooth and HDMI audio work
correctly, so the bug is isolated to the internal Realtek ALC294
codec handled by SOF (Sound Open Firmware).
## Symptoms
* PipeWire Speaker sink shows state RUNNING during playback
* Volume at 100%, not muted (PipeWire, amixer)
* Master / Speaker ALSA controls at 100%, switches ON
* Auto-Mute Mode is DISABLED
* Codec pin 0x14 (Speaker) has output enabled (Pin-ctls 0x40: OUT)
* Codec pin 0x14 EAPD is set (0x2)
* Codec pin 0x14 Amp-Out vals: [0x00 0x00] -- MUTED at hardware level
* No sound from internal speakers regardless of application
## Root cause hypothesis
The SOF topology file `intel/sof-ipc4-tplg/sof-hda-generic-2ch.tplg`
has ABI 3:29, but the kernel 7.0.0-28-generic only supports up to
ABI 3:23. The kernel log shows:
sof-audio-pci-intel-mtl: Topology: ABI 3:29:1 Kernel ABI 3:23:1
This mismatch causes the kernel to silently ignore topology features
needed to enable the Speaker pin amplifier on this ALC294 (where the
speaker is connected through a line_out pin that requires a specific
EAPD/coefficient setup).
## Hardware details
* Laptop: ASUS ExpertBook B3404CMA (vendor 1043:3870)
* CPU: Intel Meteor Lake-P
* HDA controller: 8086:7e28
* Codec: Realtek ALC294 (10ec:0294, subsystem 1043:3870)
* Topology loaded: sof-hda-generic-2ch.tplg (from firmware-sof-signed
2025.12.2-1)
## Affected software versions
* Ubuntu 26.04 LTS (Resolute Raccoon)
* linux-image-7.0.0-28-generic (also tested 7.0.0-27-generic: same issue)
* pipewire 1.6.2-1ubuntu1.1
* wireplumber 1.6.2-1ubuntu1
* firmware-sof-signed 2025.12.2-1
* alsa-ucm-conf 1.2.15.3-1ubuntu1.4
## Reproduction steps
1. Fresh install or upgrade Ubuntu 26.04 on ASUS ExpertBook B3404CMA
2. Boot normally
3. Open any audio application and play sound
4. Observe: no sound from internal speakers
5. Bluetooth headphones and HDMI output work correctly
## What I tried
1. `sudo apt install --allow-downgrades alsa-ucm-conf=1.2.15.3-1ubuntu1`
(rollback): no change
2. Boot with kernel 7.0.0-27-generic: same issue (kernel regression ruled out)
3. `blacklist snd_sof_pci_intel_mtl` to fall back to legacy HDA: results
in "Dummy Output" only, no sound card
4. `model=alc294-bass-speaker` modprobe parameter: no change
5. `hda-verb SET_AMP_GAIN_MUTE` on pin 0x14 with various channel
encodings: GET always returns 0
6. `hda-verb SET_EAPD` on pin 0x14: EAPD already set
7. Realtek coefficient writes from `goldarte/alc294_soundfix` (verbs
on NID 0x20, values 0x1b/0x4a4b and 0x0f/0x74, designed for
Vivobook K6500Z): did not change pin 0x14 state (different ALC294
variant than this ExpertBook)
## Related references
* Kernel bugzilla #206589: ALC294 no sound on Asus Zenbook (older similar bug)
* askubuntu.com #1420976: No audio on ASUS VIVOBOOK M7400Q with realtek ALC294
(same workaround verbs)
* Ubuntu Discourse: "Audio Issue on Kubuntu 26.04 LTS: Resolute Racoon"
(different codec but similar symptom pattern)
* github.com/goldarte/alc294_soundfix (Vivobook K6500Z ALC294 fix, did
not apply here)
## Workaround
Use Bluetooth headphones (Ri Buds 4 Pro confirmed working) or HDMI
audio output. The internal speakers remain unusable until this is fixed.
** Affects: linux (Ubuntu)
Importance: Undecided
Status: New
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https://bugs.launchpad.net/bugs/2162588
Title:
o audio output from internal speakers on ASUS ExpertBook B3404CMA with
Realtek ALC294
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