Moondrop DUSK-SP EQ app for Android
Contour EQ is a free, open-source Android app that reads and writes the parametric EQ stored inside the Moondrop DUSK-SP, a USB cable with a built-in DSP that ends in 2-pin IEM plugs. The EQ is stored in the cable itself, so while the cable plays your Custom EQ, it works in every app, with no system equaliser.
Stable 1.8.0
Install ContourWhat Contour does on the DUSK-SP
| Bands | Filter typesPKLSHSLPHPBPAP | Kept in the DAC | DAC settings in the app |
|---|---|---|---|
| 9 bands | 1 EQ | DAC settings: Preset |
| Supported since | Contour 1.7.0 |
|---|---|
| USB ID (VID:PID) | 35D8:1499 |
| Chip / protocol | Moondrop FreeDSP (gen 1) |
| EQ | Read and write the Custom EQ; every send is read back once the cable has restarted. The cable reports each band's gain in whole dB, while the filters Contour writes carry the exact gain. |
| Bands | 9 |
| Filter types | PEAK, LOW SHELF, HIGH SHELF |
| Gain | -12 to +12 dB |
| Q | 0.2 to 10 (shelves up to 5.02 at 12 dB of boost or cut) |
| Frequency | 20 Hz to 20 kHz |
| Preamp | none |
| Where the EQ is kept | In the cable's Custom EQ, stored with every send. After every plug-in the cable starts on its own DUSK-Default preset, with your Custom EQ still stored: the button at the foot of the EQ page then shows DUSK-DEFAULT, and a tap on it opens the DAC page, where CUSTOM EQ switches back. |
| DAC page | Since 1.7.0: PRESET, six buttons for CUSTOM EQ and the cable's five presets (DUSK-DEFAULT, DUSK-V, DUSK-HARMAN, DUSK-BASS+, DUSK-DIFFUSE-TILTED). A tap switches the cable at once and is read back, and the EQ page shows the curve of the preset you picked, from the values Crinacle, who co-tuned the DUSK, published. The choice lasts until the cable is unplugged. |
| Tested | By the developer on hardware, November 2026; the cable does not report a firmware version. Not measured on a test rig: the cable ends in 2-pin IEM plugs, which the rig cannot take, so the sound was checked by ear. |
Using Contour with the DUSK-SP
- Keep the profile to 9 bands of PEAK, LOW SHELF or HIGH SHELF, with no preamp.
- Send it with HOLD TO SEND. Contour writes all nine bands to the Custom EQ; the cable stores them and restarts, and is back on USB within about a second. Contour then switches it to the Custom EQ and reads every band back.
- Android may ask again for permission to use the cable after each send, because the restart reconnects it on USB. Allow it, and Contour finishes the read-back.
- After every plug-in the cable plays DUSK-Default. Tap the button at the foot of the EQ page, which then reads DUSK-DEFAULT, and pick CUSTOM EQ on the DAC page to hear your EQ again.
Everything else works the same on every DAC: How to use Contour.
Contour EQ and FreeDSP-Studio
Contour talks to the DUSK-SP in the protocol of FreeDSP-Studio, an open-source tool (MIT licence) whose author tested it on a DUSK-SP. That author reports that Moondrop's own app sets gains in whole dB. Contour sends the exact gain you set in the filter itself, and the cable reports it back rounded to whole dB. Contour runs on the Android phone the cable is plugged into, keeps your profiles in a library on the phone and needs no internet or account.
Questions about the DUSK-SP
Is there an app for the Moondrop DUSK-SP cable on Android?
Yes. Contour EQ reads and writes the DUSK-SP's 9-band EQ from an Android phone and switches the cable between your Custom EQ and its five presets. It is free and open source (Apache 2.0).
Why does my EQ stop playing after I unplug the cable?
It is still stored. The DUSK-SP starts on its DUSK-Default preset after every plug-in, and nothing known changes that. Pick CUSTOM EQ on Contour's DAC page and your EQ plays again.
Why does Contour show whole-dB gains after reading the cable?
The cable reports each band's gain rounded to whole dB, so a band sent at 6.7 dB reads back as 7 dB. The cable's sound comes from the filter itself, and Contour writes the exact gain into it; the reported gain is only a label. How closely the cable plays the drawn curve has not been measured.