New version here
After a year of listening to my HE400i with the previous equalizer settings I made, I decided to use a less aggressive version that only corrects the obnoxious treble peaks and compensates for the sub-bass deficiency.
Measurements and Correction
As always, the greatest appreciation goes to Solderdude at diyaudioheaven.wordpress.com. Just like last time, the measurements come straight from Solderdude’s home-made measuring rid, which I find exceedingly accurate. Check out his measurement methodology here and join the conversation at the DIYAH forum.
I averaged the left and right frequency responses and focused only on the frequency response since it is a Fourier transform of the impulse response.
While this correction is not intended to make the frequency response as quantitatively flat as possible, it does sound more natural to me. It still sounds unmistakably like a HE400i, just without the annoyance of the bass roll-off and the treble peak. Your perception may vary, due to reasons listed by Solderdude here.
Perhaps I should have listened to his advice earlier!
Use this text file in Equalizer APO (right click, save as).
Use these convolver files for ViPER4Android, Equalizer APO, Foobar, or other convolvers. Pick the one with your DAC’s sample rate.
For other parametric equalizers, use these filters:
Peak Freq=20Hz Gain=1.5dB Q=1.8 Low Shelf Freq=60Hz Gain=7dB Low Shelf Freq=300Hz Gain=1dB Peak Freq=8600Hz Gain=-8dB Q=4