Z12 Ultra – [Bug Report] High-pitched sound on Pause in MOL3 Internal Player

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1st Official Post

    Hello again,

    I have pinpointed the cause of the whistling sound and need to update my report. The issue is specifically tied to the Internal Video Player of MyTVOnline 3 on the Z12 Ultra.

    The Bug:

    A high-pitched whistling/beeping sound occurs whenever a series or movie is paused using the standard internal player of MOL3.

    Key Findings:

    • External Player Test: When I switch the player in MOL3 settings to an external player like VLC, the whistling sound does not occur. The audio remains silent during pause as it should.
    • Internal Player: The sound only happens with the default internal player.
    • CEC Independent: This happens regardless of whether HDMI-CEC is enabled or disabled.
    • Setup: Z12 Ultra -> Denon AVR-X3800H (Passthrough) -> LG C3. Even when the AVR is in standby and sound comes from the TV, the internal player causes this artifact.

    Conclusion:

    There seems to be an issue with how the internal MOL3 player handles the audio stream (or the "keep-alive" signal) during a pause state on the new Z12 Ultra hardware/beta firmware.

    Could the dev team please look into the audio driver/handling of the internal player for the Z12 Ultra?

    Thank you!

    • Official Post

    Hi,

    Could you please make Video from that whistling sound and upload to streamable.com? I tested the same after i read your post and was not able to reproduce. TV volume increased to full and Z12 volume too but everything is silent when paused.

    Quote from SAM

    Hi,

    Could you please make Video from that whistling sound and upload to streamable.com? I tested the same after i read your post and was not able to reproduce. TV volume increased to full and Z12 volume too but everything is silent when paused.

    Hi Sam,

    Thank you for your reply. I have recorded a video to demonstrate the issue. You can clearly hear the whistling sound with the internal player, which then disappears as soon as I switch to VLC.

    Video Link: https://streamable.com/peb4jd

    A few important points regarding reproduction:

    1. Model Specific: I have owned the Z8, Z10 Pro Max, and Z11 Pro Max. None of these devices had this issue. It only occurs on the Z12 Ultra.
    2. Firmware: The issue was already present in the official stable firmware. I only installed the Beta 12.10.6 hoping it would fix this specific sound issue, but it persists.
    3. Hardware Chain: My setup might be a factor: Z12 Ultra -> Denon AVR-X3800H -> LG C3. Even when the Denon is in HDMI Passthrough mode (sending sound to the TV), the whistling occurs during pause.

    In the video, I first show the playback with the MOL3 internal player (sound is audible on pause) and then I switch to VLC (silence on pause).

    Since it doesn't happen with VLC, it seems to be a specific interaction between the MOL3 internal player's audio handling and the Z12 Ultra hardware/drivers.

    Best regards!

    • Official Post

    Does the whistling sound also appear when you connect z12 directly to TV and passthrough to Denon?

    I have this config: Z12 -> LG G4 -> Denon 6400H and all fine at my end.

    Hi Sam,

    To answer your question: Yes, the whistling sound also appears when I connect the Z12 Ultra directly to the TV (bypassing the AVR).

    It is very strange because:

    Consistency: Using the exact same cable and the exact same TV port, my Z11 Pro Max works perfectly without any whistling sound. Only the Z12 Ultra shows this behavior.

    Player Dependent: As shown in the video, the sound disappears when using VLC on the Z12 Ultra, even in the same hardware setup.

    Internal Player: This leads me to believe it is a specific issue with how the MOL3 internal player interacts with the Z12 Ultra's audio drivers/hardware, as it doesn't happen with external players.

    Since you are using an LG G4 and I am using an LG C3, there might be a slight difference in how the TVs handle the audio signal during a pause, but the fact remains that the Z11 was fine and the Z12 Ultra (with internal player) is not.

    I have something similair. It's coming from the tv. Not from the speakers. (At my side)

    Also a lg 55qned866r. Looks like i hear a little fan in upper right corner from tv.

    But will test it when i hear it again also with vlc like you do.

    Maby it stops then. Again something nice to try.

    Goodday my friend.

    Edited once, last by Lucky133 (January 15, 2026 at 10:26 AM).

    Dear all,

    I am also experiencing this issue on my Formuler Z12 Ultra, and after further testing, I was able to clearly identify the root cause of the high-pitched sound.


    🎥 New video showing how to reproduce the issue:

    Watch Z12 Ultra - High pitched sound - Surround issue | Streamable
    streamable.com


    Reproducible behavior

    • When surround sound is disabled, the high-pitched noise completely disappears.
    • When surround sound is re-enabled, the high-pitched noise comes back after approximately 1 minute.
    • The delay is consistent and reproducible.

    • This happens even when:

      > no video is playing

      > the device is idle or paused

    ⸻

    Conclusion

    This behavior strongly suggests a firmware / audio driver issue related to surround (multichannel) audio handling, especially when the device is idle or when no active audio stream is present.

    The delayed reappearance (~1 minute) may indicate:

    • an audio keep-alive process
    • a background audio service
    • or a power / audio state transition that re-initializes the surround output incorrectly

    Disabling surround currently works as a temporary workaround, but surround audio should not generate any noise when no content is playing.

    ⸻

    Additional context

    • My previous Formuler devices (Z8 Pro, Z10 Pro, Z10 Pro Max, Z11 Pro, Z11 Pro Max) never showed this behavior with the same A/V setup.
    • This issue appears to be specific to the Z12 Ultra.

    I hope this additional video and explanation help you pinpoint the root cause more quickly.


    Please let me know if you need logs or additional tests.


    Thank you.

    Dylan TAÏBI

    FR/EN

    Z12 Ultra - v12.0.6-155-b42b8c1

    Sony A95L + HT-A7000 + SA-SW5 + SA-RS5

    Hi Sam,

    I have just tested the workaround mentioned by the other user, and I can 100% verify his findings.

    My test results:

    1. The 1-Minute Rule: I can confirm that the whistling sound starts exactly after about one minute of being paused or idle. This is completely reproducible on my end.
    2. Surround Sound: After disabling Surround Sound in the Android settings, the noise is completely gone. This is a working temporary solution for now.
    3. Observation on VLC: Earlier, I thought VLC fixed it, but upon closer inspection, the sound was actually still there with VLC, just much quieter. Only disabling Surround Sound in the system settings removes it entirely.
    4. Initial Suspicions: This explains why I originally suspected HDMI-CEC, as toggling CEC or switching inputs briefly interrupts the audio handshake and resets that "one-minute timer" before the noise returns.

    It is now clear that this is a specific Z12 Ultra firmware/audio driver bug related to how Surround Sound is handled in idle states. Since this never happened on my Z8, Z10, or Z11, I hope the dev team can fix this for the next Z12 update.

    Best regards!

    • Official Post
    Quote from Bangerbln

    Hi Sam,

    I have just tested the workaround mentioned by the other user, and I can 100% verify his findings.

    My test results:

    1. The 1-Minute Rule: I can confirm that the whistling sound starts exactly after about one minute of being paused or idle. This is completely reproducible on my end.
    2. Surround Sound: After disabling Surround Sound in the Android settings, the noise is completely gone. This is a working temporary solution for now.
    3. Observation on VLC: Earlier, I thought VLC fixed it, but upon closer inspection, the sound was actually still there with VLC, just much quieter. Only disabling Surround Sound in the system settings removes it entirely.
    4. Initial Suspicions: This explains why I originally suspected HDMI-CEC, as toggling CEC or switching inputs briefly interrupts the audio handshake and resets that "one-minute timer" before the noise returns.

    It is now clear that this is a specific Z12 Ultra firmware/audio driver bug related to how Surround Sound is handled in idle states. Since this never happened on my Z8, Z10, or Z11, I hope the dev team can fix this for the next Z12 update.

    Best regards!

    Thanks for the feedback. We have reproduced the issue.

    One thing I'm curious of is your volume settings. Do you guys have the volume set to max?