Subwoofer mapped incorrectly on Macbook 2.1

[Carl Englund]

It seems the 2.0 speakers get mapped to Speaker and the subwoofer is mapped to HEADPHONES, not LFE. I confirmed this by raising the volume for "headphones" in alsamixer and getting the base to play along.

However, there seems to be no workaround in Ubuntu just using the sound GUI. My guess is, if ALSA would do the mapping to LFE correctly, I could use the 2.1 hardware map in the Ubuntu sound settings and all would be well!

ProblemType: Bug
DistroRelease: Ubuntu 20.04
Package: alsa-base 1.0.25+dfsg-0ubuntu5
ProcVersionSignature: Ubuntu 5.4.0-52.57-generic 5.4.65
Uname: Linux 5.4.0-52-generic x86_64
ApportVersion: 2.20.11-0ubuntu27.11
Architecture: amd64
AudioDevicesInUse:
 USER PID ACCESS COMMAND
 /dev/snd/controlC0: diskdoc 3271 F.... pulseaudio
CasperMD5CheckResult: skip
CurrentDesktop: MATE
Date: Tue Nov 10 21:33:29 2020
InstallationDate: Installed on 2020-10-08 (33 days ago)
InstallationMedia: Ubuntu-MATE 20.04 LTS "Focal Fossa" - Release amd64 (20200423)
PackageArchitecture: all
SourcePackage: alsa-driver
Symptom: audio
Symptom_AlsaPlaybackTest: ALSA playback test through plughw:Intel successful
Symptom_Card: Inbyggt ljud - HDA Intel
Symptom_PulsePlaybackTest: PulseAudio playback test successful
Symptom_Type: Only some of outputs are working
Title: [HDA-Intel - HDA Intel, playback] Playback problem
UpgradeStatus: No upgrade log present (probably fresh install)
dmi.bios.date: 06/27/07
dmi.bios.vendor: Apple Inc.
dmi.bios.version: MB21.88Z.00A5.B07.0706270922
dmi.board.asset.tag: Base Board Asset Tag
dmi.board.name: Mac-F4208CAA
dmi.board.vendor: Apple Inc.
dmi.board.version: PVT
dmi.chassis.asset.tag: Asset Tag
dmi.chassis.type: 10
dmi.chassis.vendor: Apple Inc.
dmi.chassis.version: Mac-F4208CAA
dmi.modalias: dmi:bvnAppleInc.:bvrMB21.88Z.00A5.B07.0706270922:bd06/27/07:svnAppleInc.:pnMacBook2,1:pvr1.0:rvnAppleInc.:rnMac-F4208CAA:rvrPVT:cvnAppleInc.:ct10:cvrMac-F4208CAA:
dmi.product.family: MacBook
dmi.product.name: MacBook2,1
dmi.product.sku: System SKUNumber
dmi.product.version: 1.0
dmi.sys.vendor: Apple Inc.

[Carl Englund (englundc)]

This problem persists on the same system with all the latest updates. I did however notice that in the "hardware" part of the GUI there is no longer a "2.1" option, so defaulting to analogue stereo output.

I tried connecting an external speaker ("headphone") and it sounded as it should.