not sure if I just reply to you or not ..  I've managed to install mainline kernel .5.2.   and 5.0 and then come forwards to even the latest 5.6 and the problem is still there ...
Regards Adrian

________________________________
From: <email address hidden> <email address hidden> on behalf of Hui Wang <email address hidden>
Sent: Thursday, April 30, 2020 1:30 PM
To: <email address hidden> <email address hidden>
Subject: [Bug 1875828] Re: [HDA-Intel - HDA Intel PCH, playback] Hum problem

For example, to install mainline kernel 5.2-rc6:
https://kernel.ubuntu.com/~kernel-ppa/mainline/v5.2-rc6/

or mainline kernel 5.0: https://kernel.ubuntu.com/~kernel-
ppa/mainline/v5.0

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https://bugs.launchpad.net/bugs/1875828

Title:
  [HDA-Intel - HDA Intel PCH, playback] Hum problem

Status in alsa-driver package in Ubuntu:
  New

Bug description:
  On upgrading from Ubuntu 18LTS  to 20.04LTS I find that if I stop
  playing sound 5 seconds after stopping any correctly playing sounds
  (video / music / radio / system ) a loud hum starts in both speakers.
  This is volume independent.  Before the speakers would just turn off
  automatically and go into standby mode.

  expected action...........    stop playing a sound and speakers go
  silent

  current action ..........   stop playing a sound and 5 seconds later
  speakers go from silent to a loud volume independent hum

  ProblemType: Bug
  DistroRelease: Ubuntu 20.04
  Package: alsa-base 1.0.25+dfsg-0ubuntu5
  ProcVersionSignature: Ubuntu 5.4.0-26.30-generic 5.4.30
  Uname: Linux 5.4.0-26-generic x86_64
  ApportVersion: 2.20.11-0ubuntu27
  Architecture: amd64
  AudioDevicesInUse:
   USER        PID ACCESS COMMAND
   /dev/snd/controlC0:  adrian     2706 F.... pulseaudio
   /dev/snd/pcmC0D0p:   adrian     2706 F...m pulseaudio
   /dev/snd/controlC1:  adrian     2706 F.... pulseaudio
  CasperMD5CheckResult: skip
  CurrentDesktop: ubuntu:GNOME
  Date: Wed Apr 29 10:13:38 2020
  InstallationDate: Installed on 2018-05-20 (709 days ago)
  InstallationMedia: Ubuntu 18.04 LTS "Bionic Beaver" - Release amd64 (20180426)
  PackageArchitecture: all
  SourcePackage: alsa-driver
  Symptom: audio
  Symptom_AlsaPlaybackTest: ALSA playback test through plughw:PCH successful
  Symptom_Card: Sound Core3D [Sound Blaster Recon3D / Z-Series] (SB1570 SB Audigy Fx) - HDA Creative
  Symptom_PulsePlaybackTest: PulseAudio playback test successful
  Symptom_Type: None of the above
  Title: [HDA-Intel - HDA Intel PCH, playback] Playback problem
  UpgradeStatus: Upgraded to focal on 2020-04-24 (5 days ago)
  dmi.bios.date: 11/07/2017
  dmi.bios.vendor: American Megatrends Inc.
  dmi.bios.version: F23
  dmi.board.asset.tag: Default string
  dmi.board.name: H110M-S2H-CF
  dmi.board.vendor: Gigabyte Technology Co., Ltd.
  dmi.board.version: x.x
  dmi.chassis.asset.tag: 7438200-003
  dmi.chassis.type: 3
  dmi.chassis.vendor: NOVATECH LTD
  dmi.chassis.version: V1.0
  dmi.modalias: dmi:bvnAmericanMegatrendsInc.:bvrF23:bd11/07/2017:svnNOVATECHLTD:pnMBB-71004:pvrV1.0:rvnGigabyteTechnologyCo.,Ltd.:rnH110M-S2H-CF:rvrx.x:cvnNOVATECHLTD:ct3:cvrV1.0:
  dmi.product.family: AMI PLATFORM
  dmi.product.name: MBB-71004
  dmi.product.sku: MBB-71004
  dmi.product.version: V1.0
  dmi.sys.vendor: NOVATECH LTD

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