A Stream Deck plugin for the JBL Quantum 950 Wireless headset.
Control your JBL Quantum 950 Wireless headset directly from an Elgato Stream Deck - JBL QuantumENGINE doesn't need to be running. The plugin talks to the headset's USB dongle over a reverse-engineered HID protocol and shows live status on your keys and dials. EQ presets are read from your QuantumENGINE installation (see EQ presets).
This project is not affiliated with, endorsed by, or supported by JBL / HARMAN. Use at your own risk. The author is not responsible for any hardware damage or software conflicts.
Due to recent changes in the Elgato Maker Agreement, developers are now required to accept comprehensive personal liability and indemnification clauses under Californian law. As an independent developer offering free, open-source hobby projects, I cannot accept these legal and financial risks.
Therefore, this plugin—and all future updates to my existing plugins—will exclusively be published here on GitHub. You can always find the latest, safe-to-use .streamDeckPlugin files directly on the Releases page.
| Action | Type | What it does |
|---|---|---|
| Mute | Key | Toggles mic mute. Shows a microphone icon: white when live, red and crossed out when muted. Offline / No Dongle states show a configurable header and colors. |
| ANC / Ambient | Key | Cycles Off → Noise Cancelling → Ambient Aware, colors configurable |
| Spatial Sound | Key | Cycles Off → Fixed → Head Tracking, colors configurable |
| Battery | Key | Live battery level drawn as a battery that fills according to the charge, with configurable thresholds and colors |
| Game-Chat Balance | Dial | Custom display: JBL header, live battery readout, headset icon and a two-color balance bar. Rotate to adjust, press to reset to 50/50. Last value is persisted. |
| EQ Preset | Key | Applies an EQ preset from QuantumENGINE - system presets and your own. Shows the preset name, highlighted when active. Optional: apply right when chosen in the Property Inspector. |
| EQ Preset Dial | Dial | Rotate to browse all EQ presets, press or tap to apply. |
Every key can show a configurable header text (default JBL) in the top-left corner -
toggle it on/off and change the text per action in the Property Inspector.
All actions react instantly to changes made elsewhere (headset buttons, the wheel on the earcup, or QuantumENGINE) and show OFFLINE when the headset is powered off and NO DONGLE when the USB dongle is unplugged, including automatic reconnect. Offline and No-Dongle colors are configurable per action.
- JBL Quantum 950 Wireless with its 2.4 GHz USB dongle
- Elgato Stream Deck software 7.1+ (SDK v3, Node.js 20 plugin runtime)
- Windows 10/11 (developed and tested on Windows; macOS untested)
- For the EQ actions only: JBL QuantumENGINE installed (Windows), see EQ presets
- Download the latest
com.holgermilz.myjbxheadsetcontrol.streamDeckPluginfrom the Releases page. - Double-click the file - the Stream Deck app installs the plugin automatically.
git clone https://github.com/666mille/MyJBxHeadsetControl.git
cd MyJBxHeadsetControl
npm install
npm run build
streamdeck link com.holgermilz.myjbxheadsetcontrol.sdPluginstreamdeck is the Elgato CLI
(npm i -g @elgato/cli). For development use npm run watch, which rebuilds and
restarts the plugin on every change. Note: watch only reloads the plugin code -
after changing the manifest, layouts or Property Inspector HTML, quit the Stream
Deck app completely and restart it.
node-hid and koffi are native modules and are not bundled into plugin.js, so they
have to ship inside the plugin folder. Install them there before packing:
cd com.holgermilz.myjbxheadsetcontrol.sdPlugin
npm install --omit=dev
cd ..
npm run packThe plugin folder contains its own small package.json for this ("type": "module",
dependencies node-hid and koffi).
npx tsx test-eq.ts list # presets from q950.dat + DLL self-test
npx tsx test-eq.ts send "FLAT" # send a preset to the headsetQuit the Stream Deck app first, so the plugin doesn't hold the dongle at the same time.
- Close JBL QuantumENGINE while using the plugin if you notice conflicts - both talk to the same HID interface.
- The dial shows the current game/chat split; the colored numbers and the bar use the configurable chat and game colors.
The EQ actions use the presets you see in JBL QuantumENGINE, including your own:
- Presets are read from
C:\ProgramData\QuantumENGINE\q950\q950.dat. Create or edit presets in QuantumENGINE, they show up in the plugin automatically. - The headset expects precomputed filter coefficients. The plugin computes them with
libAirohaEQSerializeImp.dllfrom your local QuantumENGINE installation (found automatically, or set the path in the Property Inspector). The DLL is not part of this plugin. - On start the plugin runs a self-test: it computes FLAT and compares it byte for byte with the data QuantumENGINE sends. If it doesn't match, the EQ actions stay locked and nothing is sent. This matters because a wrong coefficient block can mute the headset until a valid preset is sent.
- QuantumENGINE doesn't notice presets applied by the plugin and keeps showing its own last selection. The headset still uses the preset sent by the plugin.
Without QuantumENGINE installed, all other actions work as usual; the EQ actions show Locked in the Property Inspector.
The headset shows OFFLINE even though it is on
The dongle only reports the headset once it has received a real status update. If you turn the headset on after the PC (or after Stream Deck started), the plugin may not have seen a status packet yet. To force one:
- turn the volume wheel a notch, or
- toggle ANC / mute once, or
- power the headset off and on again.
Any of these makes the headset send a status packet, and the display switches to online immediately. Tip: switching the headset on while the PC is already running usually avoids this entirely.
Nothing updates / values are stuck
Make sure JBL QuantumENGINE is closed, then quit and restart the Stream Deck app.
EQ actions show "Locked" or the preset list stays empty
The status line in the Property Inspector shows the reason. Usually the DLL wasn't
found: enter the path to libAirohaEQSerializeImp.dll (typically
C:\Program Files\JBL\QuantumENGINE\PEQ\) in the Property Inspector.
An empty list means q950.dat couldn't be read - start QuantumENGINE once so it creates it.
Logs
%appdata%\Elgato\StreamDeck\Plugins\com.holgermilz.myjbxheadsetcontrol.sdPlugin\logs
The Quantum 950 dongle exposes several HID collections on USB interface 5. The plugin opens the vendor collection with a single shared handle:
- Events in: the dongle pushes status packets (
86 00 dd ...) for battery, mute, ANC, ambient aware, spatial mode, game-chat balance and headset power. A watchdog additionally polls the device list to detect dongle unplug/replug. - Commands out: settings are written as 64-byte feature reports
(
88 00 dd 02 00 01 00 05 00 <codeA> <codeB> 01 00 <value>).
Connection state starts pessimistically as offline and only turns online on the first genuine status packet from the headset (known status code or head-tracking data). Plain dongle background traffic is deliberately ignored, so an unpowered headset is correctly shown as OFFLINE. The state stays online until the explicit power-off event arrives or the dongle is removed.
State is kept in memory with a pub/sub mechanism (mirrored to disk in a debounced, bundled write) so every key and the dial update immediately when anything changes.
An EQ preset in QuantumENGINE is just 10 gain values (31 Hz to 16 kHz). The headset, however, can't do anything with gain values on its own - its DSP needs ready-made filter coefficients (one peaking filter per band, for several sample rates). QuantumENGINE computes them on the PC and sends both to the headset. The plugin does the same:
- Read the preset - name, frequencies, gains and Q of all presets come from
QuantumENGINE's
q950.dat, including your own presets. - Build the band info (
0x0E02) - band values plus the preset name. The plugin builds this block itself. - Compute the coefficients (
0x0E7F, 858 bytes) - this is what actually changes the sound. The math lives in the functionserializePEQinsidelibAirohaEQSerializeImp.dll, which ships with QuantumENGINE. The plugin loads this DLL from your local installation via koffi and calls it with the preset's values - exactly like QuantumENGINE does. The DLL is not included in this plugin and is only used for this step. - Self-test - before the first use, the plugin computes FLAT and compares the result byte for byte with the data captured from QuantumENGINE. Only if it matches are the EQ actions enabled. A wrong coefficient block can mute the headset until a valid preset is sent, so nothing is sent without a passing self-test.
- Send - both blocks go out as multi-packet feature reports (54-byte chunks), in the same order and timing as QuantumENGINE: band info first, a short pause for the headset's acknowledgement, then the coefficients.
Why not compute the coefficients without the DLL? The exact fixed-point format and ordering inside the 858-byte block could be partly reverse-engineered, but not byte-exact. Using JBL's own function guarantees the headset gets the same data as from QuantumENGINE.
Protocol reverse-engineered with a USB analyzer and a lot of patience.
Special thanks to @Shiro836 for the EQ research: the
EQ feature IDs, the insight that the coefficients come from serializePEQ in
QuantumENGINE's DLL, and the verified preset data that made the EQ support possible.
Built with the Elgato Stream Deck SDK, node-hid and koffi.
MIT (c) 2026 Holger Milz