HDMI ARC on WiiM Ultra causing analog outputs to stay “active” (Hypex FA252 never enters auto-sleep)

[Murkas]

Hi,
I’m trying to diagnose an issue with my setup and would appreciate any insight.

Setup

• Samsung Frame TV (2023)
• WiiM Ultra
• Analog RCA output → two Hypex FA252 amplifier modules
• HDMI ARC from TV → WiiM Ultra
• All devices share the same mains power

Problem
As soon as HDMI ARC is connected between the TV and the WiiM Ultra, the analog output on the Ultra becomes electrically “active”, even when:

• the TV is idle
• no audio is playing
• HDMI ARC is not the selected input
• the WiiM Ultra is in standby

This low-level activity is enough to wake the Hypex FA252 modules and prevent them from entering auto-standby.
There is no audible noise from the speakers — the amplifiers simply detect a small signal on the RCA line.
I have set the sensitivity of the auto on/auto off on the Hypex modules to 4/4 which is the highest setting.

If I disconnect HDMI from the WiiM Ultra, the analog output becomes completely silent and the Hypex amps behave normally.

Additional tests:

• Different HDMI cables → no change
• CEC off → no change
• ARC off → no change
• Optical/coax/headphone outputs are completely clean (Hypex sleeps normally)
• Tested with a second WiiM Ultra → identical behavior
• HDMI connected only on the WiiM side (TV end unplugged) → no issue

The interference only appears when the HDMI link to the TV is active.

It seems like HDMI handshake / ground reference / digital noise from the TV is leaking into the Ultra’s analog output stage.

Questions:

1. Has anyone measured or observed similar HDMI-related leakage on WiiM devices (or other streamers)?
2. Could this be solved with full galvanic isolation on HDMI (e.g., optical HDMI extender), or is it a design limitation of the Ultra?
3. Is there a known workaround besides abandoning HDMI ARC?

Thanks in advance — any technical input is appreciated.

Markus

 

[staticV3]

I have set the sensitivity of the auto on/auto off on the Hypex modules to 4/4 which is the highest setting.

Have you tried setting it to the lowest value?

 

[Murkas]

Have you tried setting it to the lowest value?

Yep, there is where i started as it is the default and most sensitive setting. At no setting the amps will go to sleep (1-4) with HDMI cable inserted in Wiim Ultra.
On setting 4 I am able to keep the amps off, but once they are on they will never go off again.

 

[Soniclife]

What do you have the standby mode set to in the Wiim?

 

[Murkas]

What do you have the standby mode set to in the Wiim?

5 minutes

 

[Soniclife]

5 minutes

Does it do to standby?

 

[Murkas]

Does it do to standby?

Yes.

 

[MoreWatts]

If the amps have trigger inputs, use the trigger output from the WiiM. I can hear my amp click in/out of standby as my television is turned off/on.

 

[Murkas]

If the amps have trigger inputs, use the trigger output from the WiiM. I can hear my amp click in/out of standby as my television is turned off/on.

Unfortunately they don’t have trigger inputs.
I am getting desperate and thinking of buying an optical hdmi cable to see if it gets better…

 

[Soniclife]

Unfortunately they don’t have trigger inputs.
I am getting desperate and thinking of buying an optical hdmi cable to see if it gets better…

Do you have something like a headphone amp you could plug it into and turn up the volume to find out what it sounds like?

 

[Mort]

You did the troubleshooting quite well. Have you raised this on the Wiim forums?

 

[phofman]

It's possible you are having some ground loop currents (TV - wiim - amps - some other device?) which create noise voltage on the single-ended analog interconnects, causing the amps to avoid sleep. It's rather unusual ground currents in a TV would be so large that ground loop currents were so significant, but technically it is possible. Or perhaps there is some other high-current device somewhere in the chain (a PC, ntb, etc.)?

 

[Sokel]

Do you have something like a headphone amp you could plug it into and turn up the volume to find out what it sounds like?

A DMM would be better, measuring directly at the speaker's binding posts, both AC and DC.
Whatever signal it is that keeps them alive will be amplified by amp's gain and easy to detect this way.

 

[Murkas]

It's possible you are having some ground loop currents (TV - wiim - amps - some other device?) which create noise voltage on the single-ended analog interconnects, causing the amps to avoid sleep. It's rather unusual ground currents in a TV would be so large that ground loop currents were so significant, but technically it is possible. Or perhaps there is some other high-current device somewhere in the chain (a PC, ntb, etc.)?

I don’t have anything else connected to the tv or the wiim. This is it.

You did the troubleshooting quite well. Have you raised this on the Wiim forums?

Thanks, I just sent a ticket to them. Let’s see what they come back with.

Do you have something like a headphone amp you could plug it into and turn up the volume to find out what it sounds like?

Unfortunately I don’t…

A DMM would be better, measuring directly at the speaker's binding posts, both AC and DC.
Whatever signal it is that keeps them alive will be amplified by amp's gain and easy to detect this way.

As these are active speakers I guess I need to measure directly at the binding post of the driver to get a amplified signal, or on the amp directly.

 

[Sokel]

As these are active speakers I guess I need to measure directly at the binding post of the driver to get a amplified signal, or on the amp directly.

If the DMM is sensitive enough it will capture the low level signal as well, is just easier if it's amplified.

 

[Murkas]

If the DMM is sensitive enough it will capture the low level signal as well, is just easier if it's amplified.

Thanks, so what should I be measuring?

 

[MoreWatts]

How about the 'digital out' of the TV, which is SPDIF via coax or optical, to the optical input on the WiiM. This is not as 'high/curent tech' as HDMI eARC, of course. You won't be able to use the TV remote for volume control, so you'll have to use the WiiM's.

Before the WiiM Ultra, I had an old-school digital preamp connected this way. The balanced output to the amp made it go in and out of standby with the TV signal. It did not respond as fast as my current set-up with the WiiM trigger. But it did work.

 

[Murkas]

How about the 'digital out' of the TV, which is SPDIF via coax or optical, to the optical input on the WiiM. This is not as 'high/curent tech' as HDMI eARC, of course. You won't be able to use the TV remote for volume control, so you'll have to use the WiiM's.

Before the WiiM Ultra, I had an old-school digital preamp connected this way. The balanced output to the amp made it go in and out of standby with the TV signal. It did not respond as fast as my current set-up with the WiiM trigger. But it did work.

Thanks, I went for my second Ultra just so that I (the family) could have only one remote and not fiddle around with multiple.

 

[Sokel]

Thanks, so what should I be measuring?

First measure AC and then DC (we should always measure DC, at all gear, even right out of the box, you never know how they traveled, a device outputting significant DC, over a few mV at line level and more than 20-30mV at speaker's binding posts is defective probably)
If the DMM does not have auto scaling just put it at the lowest mV scale.

You may have to wait some seconds if the signal is some kind of repeated pulse or something similar.

 

[phofman]

I don’t have anything else connected to the tv or the wiim. This is it.

OK, but to me some ground issue seems like the most likely culprit of this. Wiim Ultra converts the incoming HDMI/ARC in a separate chip EP950E to I2S and feeds this to the Linkplay ARM SoC module. If the software in wiim is switched to other source, I do not see how any incoming signal on one of the SoC I2S interfaces which is not being read by the software could leak into the output digital signal for the built-in DACs. However a ground current could create a noise voltage on the analog lines to the amp modules. Both TV and the amps are class I, IMO creating a ground loop. I would suggest to do a standard ground loop diagnosis - e.g. carefully disconnecting (just for testing) the PE wire of one of the devices to break the loop to see what happens.