CHU 2 Studio

Tune the EQ inside your Moondrop CHU 2 DSP earphones, from Windows, for free.

The CHU 2 DSP has a small equaliser built into its USB-C cable. Moondrop's own Hub app does not support this model, so there was no way to change that EQ. CHU 2 Studio does it: you pick a sound, press Save, and the earphones keep it — on your phone, on a console, on any PC, with no app running.

Not affiliated with, or endorsed by, Moondrop. MIT licence.

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Install

Download from the latest release — either one works:

• CHU2Studio-0.2.4-setup.exe — the installer. Puts CHU 2 Studio in your Start menu, offers to start it with Windows, and uninstalls from Settings like any other program. It installs for you alone, so it never asks for an administrator.
• CHU2Studio-0.2.4-win64.zip — no installing. Unzip it anywhere and run CHU2Studio.exe. To remove it, delete the folder.

No admin rights and no driver either way. Windows 10 or 11, 64-bit. Your presets and settings live in %APPDATA%\CHU2Studio and are left alone by the uninstaller.

The app is not signed yet, so Windows may show "Windows protected your PC". Choose More info → Run anyway. The .exe is built from this repository with python packaging/build_exe.py, so you can also build your own.

To remove everything, uninstall (or delete the folder) and then delete %APPDATA%\CHU2Studio (Settings → Open data folder), which holds your presets, settings and the backup of your earphones' original EQ.

What it does

• Quick Tune — five ready sounds (Music, Gaming, Movies, Competitive FPS, Calls), each with a strength control and plain-language tweaks such as "Cleaner bass" or "Less sharp cymbals".
• Build PEQ — the five bands the chip has, on a graph you can drag, with numbers you can type. Undo and redo included. The chip gives you the full range: 20 Hz to 20 kHz in 1 Hz steps, ±12 dB in 0.1 dB steps, Q from 0.1 to 10 — finer control than Moondrop's own FreeDSP cable offers.
• Hear before you save — every change plays at once. Nothing is written to the earphones until you press Save.
• Import and share — read AutoEq, Equalizer APO and Peace files, export the same, or copy a short share code. A file with ten filters will not fit five bands, so it keeps the five whose combined curve comes closest to the whole file, and tells you how far off that lands in dB.
• Six measured tunings — the Chu 2 has been measured by crinacle, HypetheSonics, Kazi, Super Review and ToneDeafMonk, and AutoEq turned each measurement into a correction. All six are built in under Presets → Measured. Nothing is downloaded; the app makes no network calls.
• No clicking — the CHU 2 switches its amplifier off when it sees no audio for about half a minute, and clicks when it comes back, so every video, track and notification starts with a pop. The app plays it a 5 Hz tone, below hearing and below what the drivers can reproduce, so the chip stays awake and you hear nothing. On by default.
• Lives in the tray — closing the window hides the app instead of quitting, so the clicking stays away and your earphones stay connected. Right-click the tray icon to show it, flip the clicking switch, or quit for real. It can start with Windows, straight into the tray.
• Presets — a library with your own saved EQs and favourites.
• Safe by design — the first time it connects, it saves your earphones' original EQ on your PC. "Restore original" puts it back at any time.

Quick Tune — pick a sound, add tweaks in plain words, choose how strong:

Presets — your own EQs and the ready ones, with a badge on the one your earphones have:

Import and share — paste a share code or an AutoEq file and see what the five bands will be, before anything changes:

Good to know

• Saving restarts the earphones for about a second, and the sound stops during that. This is the chip, not a bug.
• The chip has no volume control of its own. A boost can distort, so the app quietly lowers the whole EQ by the size of the biggest boost. That makes the sound quieter; turn your volume up when you compare.
• Unsaved changes are lost when you unplug. The saved EQ comes back.
• A click before every sound is the earphones, not the app. The CHU 2 mutes its own amplifier whenever nothing is playing, and clicks when it switches back on, so a video, a track or even a notification starts with a pop. CHU 2 Studio stops that out of the box by playing silence, and closing the window leaves the app in the tray so it keeps working. Settings → Starting can have it there from login. Turn it off in Settings → Clicking if you use an app that takes exclusive control of the sound card.
• Crackling after the PC wakes from sleep is a different fault. Windows powers the CHU 2 down while idle and it comes back with its audio out of step; a restart does not help, because the USB ports stay powered. Untick Allow the computer to turn off this device to save power on the USB Composite Device in Device Manager, or set USB selective suspend to Disabled in your power plan.
• Use one equaliser, not two. The EQ lives in the cable, so leave Windows' own enhancements off and do not run Equalizer APO or Peace on the same device at the same time. Two layers add up: a +3 dB bass shelf here plus another in Windows is +6 dB, which distorts. The app works out how much headroom its own five bands need, but it cannot see anything stacked on top, so that protection quietly stops being enough.
• It changes what you hear, not your microphone.

For developers

python -m venv .venv
.venv\Scripts\python -m pip install -e ".[dev]"
.venv\Scripts\python -m playwright install chromium   # for the UI tests

.venv\Scripts\python -m pytest -q tests               # 262 tests
.venv\Scripts\chu2-studio --fake-device               # run without hardware
.venv\Scripts\python -m pip install -e ".[build]"
.venv\Scripts\python packaging/build_exe.py           # the .exe and the zip

The app is Python with a pywebview window and a Vue page (vendored, no Node). src/chu2/ holds the device code; src/chu2/app/ holds the window, and src/chu2/app/ui/ the page.

The USB side needs no driver: the CHU 2's control channel is a HID device that Windows shares, so hidapi reaches it. The commands are written down in docs/PROTOCOL.md, and docs/API.md describes the Python modules.

There is also a command line for the EQ in the device:

chu2 dsp read          # show the EQ the CHU 2 has stored
chu2 dsp write my.json # write it, check it, save it
chu2 dsp restore       # back to the EQ found before the first write

Thanks

• devicePEQ — the KTMicro command format that made this possible.
• AutoEq by Jaakko Pasanen (MIT) — the six measured tunings under Presets → Measured, and the people who measured the Chu 2 for them: crinacle, HypetheSonics, Kazi, Super Review and ToneDeafMonk.
• Catppuccin (themes), Phosphor Icons, Inter, Newsreader and JetBrains Mono (fonts), Vue — each under its own licence, listed in the app under Settings → About.
• Moondrop, for the CHU 2 and its DSP.