#168 APO stopped working after recent Windows 10 update

[Cmd]

I've been using Equalizer APO for it's preamp to reduce the default volume of my logitech USB headset to non-earshattering levels (thanks Windows usb drivers). However, since a recent Windows 10 update Equalizer APO has stopped working on my system.

I can install and tweak the settings just fine with the Configurator and Configuration Editor, but nothing seems to affect the final audio mix to my headset.

I have installed the APO on all playback devices, tried uninstalling and reinstalling with the latest version, and even installed the SFX/EFX experimental version to my headphones (as it seemed to work for another user).

Enhancements are enabled for the headset driver. No error logs are present in 'C:\Windows\ServiceProfiles\LocalService\AppData\Local\Temp\EqualizerAPO.log'.

Windows 10 Version: 10.0.19042 Build 19042

Attached images show the current set up.

Thanks for your time.

[Peter Verbeek]

I'm guessing the pre amp of -100 dB isn't your normal setting as this could effectively mute all channels of all devices. But reading the term "earshattering" I assume you need the -100 dB but without a device selection command all devices have -100 dB so no sound and no mic recording.

[Cmd]

Thanks for the fast reply!
You're right, -20dB is my default -- I boosted it to -100dB while troubleshooting, so that I'd know for sure if the preamp was working. Unfortunately the headset volume comes through loud and clear, the same as without Equalizer APO.

I've only installed Equalizer APO on playback devices, so mic output is unaffected and works just fine.

Cheers

[Peter Verbeek]

So Equalizer APO isn't working any longer on the Logitech? Usually this is caused by a new driver update of Logitech which came with the Windows update. Although SFX/EFX is the obvious thing to try on Windows 10 in this case I would try unchecking the "Use original APO" checkboxes. Or even uninstall the GHub software of Logitech. Somehow the audio enhancements (Audio Processing Objects APO's) of GHub is conflicting with Equalizer APO. Are you using the audio enhancements of GHub like surround sound?

[Cmd]

I gave without "use original APO" a shot and it disabled the virtual surround enhancement I had active, so that seems to work, but the volume was otherwise unchanged. I think my headphones (H390) are too cheap to qualify for proprietary drivers, as I don't have GHub. When checking the drivers in device manager it reads as using Microsoft's Audio Endpoint (updated to latest version 10.0.19041.1) with driver details telling me 'no driver files required or loaded for this device'.

It's almost like Microsoft's default USB speaker driver no longer supports the APO, although that can't be true as it's dated to 6/12/2019. Would you be able to give me the process/service name so I can check APO is running at startup correctly, and not being blocked by anything?

[Peter Verbeek]

Equalizer APO doesn't have a service. The idea is that it's an APO of the device driver itself. The Configurator of Equalizer APO changes some registery keys of an audio device in order to reroute the audio stream of that device through EqualizerAPO.dll, the audio processing engine. I don't know how or if this dll file is shown in the list of processes. The way I check if everything is alright is by changing the pre amp. That's also what I advise my Peace users to do.

There are several ways that Equalizer APO is blocked. For instance, an anti-virus app may prevent writing to config.txt or it blocks the changes by the Configurator of the Windows registry so the rerouting isn't done or gets undone.

If you're using a default Windows USB driver usually things are fine. It has APO capabilities so something else is wrong. Always the best approach is to make sure that Equalizer APO is working on the speakers output (3.5 inch jacks) of the computer. It's either a matter of Equalizer APO not working at all or not working on the specific device. Both need to be approach differently.

[Cmd]

Using a 3.5mm on a Realtek line out (which also has Equalizer APO installed) also had no preamp, so I suspect it is something on my system.

I checked the registry and all expected keys seem to be there. Attached is a shot of the ChildAPOs registry key, and also the registry for the key specified when I click "Copy device command to clipboard" within the Configurator.

I haven't changed any of the security settings on my system lately. My only active anti-virus is Windows Defender, which updates regularly -- latest update was today so I can't backdate the last installation to when the error began, sorry.

Cheers

[Peter Verbeek]

Yes, all seem okay. Unfortunately, I'm not an expert on the details. I wish the developer would take a look at it. Are there child apo subkeys present in HKEY_LOCAL_MACHINE\SOFTWARE\EqualizerAPO\Child APOs? Another thing to check is if nothing is blocking the writing to config.txt. When this happens Equalizer APO processing engine doesn't get commands.

[Cmd]

Yup, ChildAPOs are present. The settings for the default device are as attached. Config.txt has open read permissions (writing is more limited, but the engine should only need read permissions?).

I'll play around a bit more with my computer settings, but I think we've narrowed down that this is a local issue with something on my system screwing it up -- and at this point, it's just trial and error. I'll keep you updated if I find a fix that works.

Thanks for your help Peter, and the time and energy you've put into supporting this project. Much appreciated.

[Peter Verbeek]

I think, the audio processing only needs read rights. Interface apps like Peace and the Configuration Editor need write, creation and deletion rights so basically all rights.

[Cmd]

Well, all of a sudden it's working again! I suspect it has to do with Microsoft Defender Antivirus having just updated to KB2267602 (v1.339.1904.0). Seems like the registry was indeed being blocked by Microsoft Defender. Hope this is of help to anyone else with the same issue.

[Peter Verbeek]

Thanks for reporting this. You're probably right in saying that Microsoft Defender blocked the registry for the Configurator of Equalizer APO. Great that the KB2267602 v1.339.1904.0 update fixed that.