How we measure

1. Acoustic coupling

HEAD acoustics HMS II.3 (calibrated quarterly by HEAD Berlin lab). The HMS II.3 head-and-torso simulator replicates average ear canal geometry with calibrated 2cc coupler. Quarterly recalibration via HEAD acoustics Berlin lab guarantees IEC 60318-7 compliance.

2. Capture and analysis

REW v5.20 + Audio Precision APx555. Frequency response captured with 200ms log sweep, 32 averages. THD captured at 90dB SPL with reference signal generator. Channel matching measured L/R simultaneously to eliminate ambient noise variance.

3. Reference rig

Stax SRM-T8000 reference + dedicated isolation. Reference amp ensures driver behavior tested without source coloration. Isolation transformer eliminates ground loop artifacts.

4. Environment

Treated room 14 sqm, RT60 0.22s, ambient noise less than 22dBA. Treatment includes broadband absorbers, low-frequency traps and diffusion at primary reflection points.

5. Protocol

Each headphone measured 7 positions, average curve published. Raw .frd files downloadable on request. Each headphone burned-in 50 hours minimum before formal measurement. Headphones removed and re-seated 7 times for positional variance averaging.

6. Raw data

Raw .frd files (frequency response data) published on request via contact form. Transparency is non-negotiable.