Sound Blaster AE-9 Linux driver — Audio Control Module, SBX effects, PipeWire

Sound Blaster AE-9 Linux support: 44 % of the card's features, 71 % of the Audio Control Module's (support matrix below). Working today on the physical card and ACM: headphone output through the Audio Control Module, ACM volume knob and dB display, mute and output toggle from the knob, SBX button and light, SBX effects with per-effect controls, PipeWire and WirePlumber integration, DKMS packaging for Ubuntu and other distributions on kernel 6.17+.

Out-of-tree Linux driver for the Creative Sound Blaster AE-9 sound card (PCI 1102:0010, dual CA0132 HDA codecs, ES9038Q2M headphone DAC, SABRE9006 line-out DAC, external Audio Control Module). Based on the kernel's snd-hda-codec-ca0132 ALSA driver, plus a small fix to the HDA core that stops the card from hard-locking the machine.

Status: working. Built and running on Linux 7.0 (Ubuntu kernel 7.0.0-31-generic) with the physical card and ACM, playback under PipeWire, no issues so far. Read Known issues and Hazards before installing. This is not (yet) upstream; the plan is to get it there.

Support matrix

Each row weighs the same; untested counts as unsupported. Overall 7 of 16 rows = 44 %, Audio Control Module 5 of 7 = 71 %.

Area	Feature	Status
ACM	Headphone output through the ACM (ES9038Q2M)	Working
ACM	Volume knob and dB display (Windows curve, −90 … 0 dB)	Working
ACM	Mute (short knob press, MUTE on the display)	Working
ACM	Output toggle (knob hold, -HP- / -SP-)	Working
ACM	SBX button and light (effects on/off)	Working
ACM	Headphone amp gain stage (IEM / Normal / High)	Not yet
ACM	Mic / line input on the ACM (6.3 mm, XLR, 48 V phantom)	Not yet (capture disabled, Hazard 4)
Card	Playback under PipeWire, 48 kHz, boot defaults, default sink	Working
Card	SBX effects: master switch and per-effect switches/levels	Working
Card	Rear line-out (SABRE9006)	Not yet
Card	Optical S/PDIF out	Untested
Card	Rear line-in / mic-in	Not yet (capture disabled, Hazard 4)
Card	Optical S/PDIF in	Untested
Card	Mic effects (CrystalVoice)	Not yet (needs capture)
Card	Direct Mode / bit-perfect, sample rates other than 48 kHz	Not yet
Card	Suspend / resume	Untested

What works

• Headphone output through the ACM (ES9038Q2M path), 48 kHz, under PipeWire.
• Volume knob: clockwise = up, two detents per point, Windows' 101-point loudness curve (−90 … 0 dB). The ACM display shows the level in Windows' format (-25.5), MUTE while muted, -HP- / -SP- when the output is switched.
• Knob press: short press (< 1.5 s) toggles mute; 1.5–3 s hold toggles the output (headphones ⇄ rear line-out); longer presses are ignored.
• SBX button: short press toggles the DSP effects (Enable OutFX); the button light shows the real effects state, off at boot. Presses of 5 s or more are ignored (Windows uses them for a display option).
• Effects: off by default ("Direct Mode"-like clean path). When on, each SBX processor (Crystalizer, Dialog Plus, Smart Volume, X-Bass, Surround, Equalizer) has its own switch and level in the mixer — see Effects below.
• Master volume on the hardware amp with the Windows curve; the DSP volume stage is fixed at 0 dB, so the knob and Master are the only level control.
• Desktop integration: the card comes up on its analog profile by itself, PipeWire's default sink is the AE-9 at unity gain, and WirePlumber is kept off the hardware mixer.
• Stability: the HDA-core posted-write fix (the stock kernel hard-locks on this card), the IOMMU requirement below, the codec held out of runtime suspend so the ACM stays alive, and serialized access to the card's DSP command engine.
• Packaging: DKMS (rebuilds on kernel updates, signs for Secure Boot), a firmware extractor for the one DSP segment that cannot be redistributed, an uninstaller.

Known issues / not done

• Rear line-out (speakers) is silent. The SABRE9006 path is configured but no analog output yet.
• Headphone amp gain stage (IEM / Normal / High) is not controllable yet; the module runs in its power-on gain. With sensitive IEMs start low (the defaults set about −25 dB).
• Effects run at Creative's stock levels, not your Windows SBX profile; there is no import.
• Bit-perfect / rate following (Windows "Direct Mode") not implemented: PipeWire resamples to 48 kHz.
• Recording from the card is disabled (Hazard 4): the capture path is not brought up and opening it hard-locks the machine. Use a USB microphone. S/PDIF, suspend/resume: untested.

Hazards — read first

1. Never load an unpatched HDA stack against this card. The stock kernel's HDA core hard-locks the machine when it probes the AE-9 (posted-write bug, patches/0001); on some boards it also kills the chipset USB controller sharing the IOMMU group. This package installs the fixed core module as an override; do not remove it while the card is in the machine unless you blacklist snd_hda_intel for it.
2. AMD IOMMU: iommu=pt is required. The AE-9's HDA controller prefetches past the end of the audio buffer; with a translating IOMMU every buffer wrap is an aborted DMA read (AMD-Vi: IO_PAGE_FAULT ... 0000:0a:00.0), which crackles and eventually stalls the DSP stream. Add iommu=pt to GRUB_CMDLINE_LINUX_DEFAULT, run update-grub, reboot. VFIO passthrough keeps working with iommu=pt.
3. The ACM can hang (module unresponsive to all traffic). A warm reboot does not clear it: power the PC fully off, wait 30 s, reseat the ACM cable, cold boot.
4. Capture (recording) from the AE-9 hard-locks the machine. The driver brings up the playback path only; the first time an application opened the card's analog capture (Discord falling back to "Default" input after a USB microphone was unplugged) the box froze with no kernel message. The shipped WirePlumber rule 52-ae9-no-capture hides every capture node of the card so desktop applications cannot select it. Do not open the card's capture devices directly with ALSA (arecord -D hw:Creative) either.
5. Do not use the diagnostic tools/acm-tool while the driver's ACM service is running (UART collision), and never run its acm=1/2 bring-up on a live card: the GPIO pulse resets both DACs. acm=3 is the UART-only mode. See Diagnostics.

Requirements

• Kernel 6.17 or newer (the codec-driver API and sound/hda/codecs layout); headers for the running kernel; dkms, gcc, make, python3, curl.
• PipeWire + WirePlumber (0.4 Lua config or 0.5 conf.d — both shipped).
• Creative's Windows driver package for the DSP firmware segment (see next section).
• Secure Boot: DKMS signs the modules with its key; enrol it once (mokutil --import /var/lib/dkms/mok.pub, reboot, enrol) or use your distribution's DKMS signing setup.

The firmware segment (why you need Creative's installer)

The DSP needs a 432-byte program patch that only exists inside Creative's CtxHda.sys. It is Creative's code and is not in this repository. tools/ae9-firmware-extract.sh carves it from the driver package you are licensed to use (the b43-fwcutter model):

1. Download Sound Blaster Command for the AE-9 (file AECMDMasterInstaller_3.4.92.00.exe, ~138 MB) from Creative's download page: https://support.creative.com/downloads/download.aspx?nDownloadId=100330. If that link is broken, find it here: https://support.creative.com/Downloads/searchdownloads.aspx?filename=SB# (search "AE-9", package "Sound Blaster Command"). The page has a licence click and a captcha, so this step is manual. No VM, nothing is executed.
2. sudo ./install.sh --exe ~/Downloads/AECMDMasterInstaller_3.4.92.00.exe (or run tools/ae9-firmware-extract.sh yourself). It unpacks two Inno Setup layers with innoextract (fetched automatically if not installed), locates the segment by signature, verifies its SHA-256 against the known-good value, and installs /lib/firmware/ae9-dsp-output-overlay.bin. A mounted Windows partition or a bare CtxHda.sys also work (--windows DIR, --sys FILE).

Install

git clone https://github.com/verzic/sb-ae9 && cd sb-ae9
sudo ./install.sh --exe ~/Downloads/AECMDMasterInstaller_3.4.92.00.exe
# AMD: add iommu=pt (Hazards, 2), then
sudo reboot

install.sh adds the DKMS module set (sb-ae9), extracts and installs the firmware segment (--no-firmware skips that step if it is already in place), installs the modprobe drop-in, the WirePlumber rule and the ae9-defaults user service, and warns about Secure Boot and iommu=pt. After the reboot the card comes up by itself.

Check: dmesg | grep 'AE-9' should show converter bring-up done and AE-9 ACM: present, firmware …, output headphone, followed a few seconds later by AE-9 ACM: regs … (amp on …). The user service ae9-defaults selects the ACM headphones, sets a safe Master level and makes the AE-9 PipeWire's default sink.

Uninstall: sudo ./uninstall.sh (the in-tree driver returns after a reboot; it does not support the AE-9).

Using it

The examples address the card by its ALSA id, -c Creative, which does not change between boots (the numeric index can).

Volume and mute

• The ACM knob, or amixer -c Creative sset Master <0-99> (Windows curve; 18 ≈ −25 dB, 44 ≈ −12 dB, 99 = 0 dB). PipeWire's slider is software gain; keep it at 100 %.
• Mute: a short knob press, or amixer -c Creative sset Master toggle. The display shows MUTE.
• The session defaults set Master to 18 at every login. To change that, override the service environment: systemctl --user edit ae9-defaults, then add

  [Service]
  Environment=AE9_LEVEL=30
  

  (AE9_OUT=Speakers selects the rear line-out instead; not yet audible, see Known issues).

Output

• amixer -c Creative sset 'AE-9 Output' Headphone|Speakers, or hold the knob 1.5–3 s.
• The control is deliberately not called "Output Select": the desktop's ALSA card profiles map that name onto sink ports and rewrite it on every route restore, flipping the ACM relay.

Effects (SBX)

• Master switch: the SBX button, or amixer -c Creative sset 'Enable OutFX' on|off. The button light follows the real state. It is off at every login (the defaults service turns it off) so the clean path is what you get by default.

• The per-effect controls only act while the master switch is on. With the light off the driver forces every output processor off in the DSP; the individual switches just remember what to re-enable when it comes back on.

• Switching the master on enables the processors below at Creative's stock levels. Each has a switch (sset 'FX: <name>' on|off) and a level 0–100 (sset 'FX: <name>' <n>).

  Processor	What it does	Stock	Notes
  FX: Crystalizer	Restores transients: sharper attacks, brighter top, more punch	on, 65
  FX: Dialog Plus	Lifts the vocal / dialogue midrange	on, 50
  FX: Smart Volume	Loudness leveler: rides the gain up in quiet passages and down in loud ones	on, 74	Causes the "volume going up and down" feel. FX: Smart Volume Setting: Normal / Loud / Night
  FX: X-Bass	Bass enhancement below the crossover	on, 50	Crossover FX: X-Bass Crossover 1–100, default 8 (≈ 80 Hz)
  FX: Surround	Virtual surround / stereo widening	off, 67	Surround Channel Config stays 2.0 for headphones
  FX: Equalizer	10-band EQ by preset	on, Flat	FX: Equalizer Preset: Flat, Acoustic, Classical, Country, Dance, Jazz, New Age, Pop, Rock, Vocal. Flat is all zeros

  Capture-side processors (FX: Voice Focus, FX: Noise Reduction, FX: Mic SVM) exist but the mic inputs are untested.

• Examples, with effects on and music playing:

  amixer -c Creative sset 'FX: Smart Volume' off     # stop the level pumping
  amixer -c Creative sset 'FX: X-Bass' off           # or a lower value, e.g. 20
  amixer -c Creative sset 'FX: Crystalizer' 30       # keep some sparkle, less punch
  amixer -c Creative sset 'FX: Equalizer Preset' Rock
  

  If a change does not seem to take, pause playback for a few seconds and resume: some DSP settings are picked up at stream start.

• Persistence: the FX: switches and levels are ordinary ALSA controls, so the distribution's ALSA state handling keeps them across reboots (on Ubuntu alsactl stores at shutdown and restores at boot; sudo alsactl store saves the current combination right away). The master switch, Master level and routing are re-applied by ae9-defaults at every login regardless. Not yet verified across a reboot on this card — check with amixer -c Creative sget 'FX: X-Bass' after the first one.

Session defaults service

ae9-defaults (user service, oneshot) runs at login: waits for the AE-9, selects its analog profile if WirePlumber did not, selects AE-9 Output = Headphone, turns effects off, sets PCM/Front/Surround to 100 % and Master to AE9_LEVEL, then makes the AE-9 analog sink PipeWire's default at unity and re-checks once after a late route restore. systemctl --user restart --no-block ae9-defaults re-applies everything (it takes up to ~45 s; --no-block returns at once). journalctl --user -u ae9-defaults shows what it did.

Checking state

amixer -c Creative sget Master; amixer -c Creative sget 'AE-9 Output'; amixer -c Creative sget 'Enable OutFX'
wpctl status                       # the AE-9 analog sink should be the starred default
dmesg | grep 'AE-9 ACM'            # knob, button and keepalive log lines

Button events are logged as AE-9 ACM: SBX button (146 ms) -> OutFX on, knob press (158 ms) -> mute toggle, knob mid press (1744 ms) -> output toggle.

ACM service

ae9_acm_poll=1 (default, /etc/modprobe.d/sb-ae9.conf) runs the ACM service: knob, display, buttons, Windows-style keepalive. ae9_acm_poll=0 initialises the module once and leaves it alone (diagnostic baseline). It can be parked at runtime for the diagnostics tool with echo 0 | sudo tee /sys/module/snd_hda_codec_ca0132/parameters/ae9_acm_poll; resuming needs a reboot.

Diagnostics (tools/acm-tool)

A throw-away kernel module that maps the card's BAR2 and talks to the ACM UART, the GPIO block and the DAC I2C command engine directly. make, then sudo ./poke.sh <params>; it loads once, prints its log lines and unloads. Park the driver's ACM service first and read Hazard 5. Modes:

• acm=3 — UART-only bring-up (safe on a live card). Combine with: acmget=<reg> read an ACM register; acmset=<reg>,<value>,<mask> write bits; acmtext=<up to 8 chars> write the display; raw=f0,22,02,01,00,f7 send one frame and print the reply.
• i2cdump=0x48 (ES9038Q2M headphone DAC) / i2cdump=0x49 (SABRE9006 line-out DAC), i2c=<group>,<reg>,<val> — DAC register access through the command engine.
• acm=1 / acm=2 — full Windows-style bring-up including the GPIO pulse that resets both DACs; only for a card without the driver loaded.

What the driver adds over the kernel's ca0132

For readers of patches/0002 and driver/ca0132/ca0132.c (QUIRK_AE9):

• Card bring-up replayed from the Windows driver: DSP master-control sequence, ASI/PLL and DAC configuration over the BAR2 command engine, the 8051 router hooks and the output-connect overlay loaded via request_firmware("ae9-dsp-output-overlay.bin").
• The ACM protocol over the 16550 in BAR2 (115200 baud, sysex-style frames): presence probe, keepalive frames, register read/write for the headphone-amp bit, display text, SBX light, button/knob event polling. ACM power-up writes GPIO pin 5 only; the Windows pin-0 pulse is never issued because it resets both DACs.
• Volume: Windows' 101-entry dB table applied on the DAC amp; the DSP volume stage parked at 0 dB at bring-up (it latches at stream start); the knob writes the Master control.
• Controls: AE-9 Output (renamed so desktop card profiles cannot rewrite it), effects master default off with an explicit effects-off push at bring-up.
• Desktop: the headphone pin is marked "no presence detect", which gives ALSA a Headphone Phantom Jack (always plugged) so the analog profile is available and WirePlumber picks it and accepts the analog sink as default.
• Robustness: codec runtime PM held (the ACM service dies in D3 otherwise) and the ACM work rescheduled on resume; DSP command-engine access serialized with a mutex (an unserialized knob/mixer collision wedged the DSP); all UART waits sleep, no busy-waiting, work on the unbound workqueue; only the amp bit is written to the ACM (the module's own selector items are read-only).
• HDA core: patches/0001 flushes posted writes in the interrupt clear path; without it the stock core hard-locks the machine on this controller.

Repository layout

• driver/ca0132/ — the codec driver (kernel sound/hda/codecs/ca0132.c + AE-9 support).
• driver/hda-core/ — kernel sound/hda/core + the posted-write fix, built as an override.
• patches/0001-… — the HDA core fix as a standalone kernel patch (upstream candidate).
• patches/0002-… — the codec changes as one diff against v7.0, for review.
• tools/ae9-firmware-extract.sh — firmware segment extractor; tools/acm-tool/ — ACM/BAR2 diagnostics.
• install/ — modprobe drop-in, WirePlumber rules (soft mixer; capture disabled), session defaults + user service.
• docs/ — the investigation log, reverse-engineering notes for the ACM protocol and the Windows bring-up, and the decoded register captures the driver was derived from.

How it was done

The Windows driver's register traffic to the card was captured and replayed: DSP master-control sequence, ASI/PLL and DAC configuration, the output-connect patch, the ACM UART protocol (sysex-style frames at 115200 baud over a 16550 in BAR2), the encoder acceleration and the volume table. Details in docs/. Prior art: the ae9_build project documented the card and the Windows registry; this work started where it stopped (the DSP output stayed silent).

License

GPL-2.0 (derived from the Linux kernel). Creative's firmware and driver binaries are not included and are not redistributed by any part of this project.