Fixed-band EQ capture & simple AutoEQ

Reverse-engineer the EQ built into a Bluetooth headphone. Describe its sliders, capture the headphone flat and then each band at its maximum and minimum, and the tool fits a real filter (centre, Q, dB per step — boost and cut separately) to every band. Load a target and the constrained AutoEQ picks the slider values that get closest, fixing bass and mids first and treating the treble as advisory.

Each step folds away once it is done; click a heading to reopen it.

1. Audio input / output

Measurement input — rig microphone interface, Cosmos ADC, or USB-C audio input Playback output — the Bluetooth headphone itself (pair it with this computer first)

Audio devices have not been scanned.

Bluetooth output usually runs at 48 kHz (or 44.1 kHz for some codecs); set the measurement input to the same rate or Chrome will refuse the capture.

2. Capture options

Start frequency (Hz) End frequency (Hz) Sweep duration (s) Wait before sweep (ms) Wait after sweep (s) Noise-floor capture (s) Output level (dBFS) Flat (EQ at 0) repeats Input channel Smoothing

Use a timing lead-in/referenceBluetooth adds latency; the lead-in keeps the deconvolution aligned.

Subtract the measured noise floor from the responseOff by default, as in REW. A steady tone in the room (a fan, a transformer) can be over-subtracted into a narrow notch; the noise floor is still measured and reported either way.

Input calibration file — microphone/interface calibration, frequency + dB columns. It is tied to the selected input device and channel and comes back whenever they are selected again, even though this box reads “No file chosen”.

Remember this calibration on this browserNo calibration loaded

3. Describe the headphone's EQ

Headphone / app name Band layout preset Default range: minimum Default range: maximum Slider step Outer bands

#	Label (Hz)	Min	Max	Step

The frequency is only the app's label. The fit finds where each band really sits, for boost and for cut separately, so an EQ whose cut is centred elsewhere (Apple's beta EQ, for one) is handled without extra input.

Load a saved profile or project (.json)

4. Capture the bands

Keep the headphone seated exactly the same throughout; do not remove it between captures. Use the headphone's own app for every change, and give the device a second to apply each setting before capturing. Boost and cut are captured separately because they are often not mirror images.

Graph

Frequency rangedB spanDrag to pan · double-click resets · dashed = fitted filter

5. Target and simple AutoEQ

Target curve (for the same rig as your capture) Target tilt (dB/octave, hinged at 1 kHz) Fit from (Hz) Fit to (Hz) Priority Band model Maximum boost allowed Prefer cuts over boosts

Your own rig target (frequency + dB columns) — uploading selects and remembers it.

No target loaded

6. Export

The profile is the file to share: the band definition, the fitted filters, the measured band shapes and the flat response. Anyone can load it on the fixed-band AutoEQ page, pick their own target and get slider values for this headphone without measuring it. Reloading it here (step 3) also skips the captures next time.
The project also carries every capture (on a 48-point-per-octave grid), the target choice and the current values, so the whole session can be restored.
Nothing is kept in the browser between visits: export the project before leaving, and load it again (step 3) to continue — captures in the file are added to whatever this session already has.