Equalizing HE400i the Mathematical Way

Warning: this project is now deprecated in favor of the second revision.

Measurement: raw uncompensated frequency response by InnerFidelity

Target frequency response: an average of 47 subjects’ head-related transfer functions by Dorte Hammershøi and Henrik Møller (recommended as most accurate on Rin Choi’s blog), with 4dB sub-100Hz bass boost for body vibration compensation.

For use with the following equalizers:

• Equalizer APO in variable band graphic equalizer mode (quasi-parametric: custom frequencies and gains, no Q/bandwidth setting because straight lines are drawn between the set points).

• EQuilibrium, a fantastic high-quality parametric equalizer with support for more bands than you’ll ever need. (Set master gain to -7.7dB or autogain.)

• Any other parametric equalizer with support for 17 or more bands. (Set preamp/master gain to -7.7dB.)

[spoiler title=’Q value parametric’ style=’default’ collapse_link=’true’]Preamp: -7.7 dB
Filter 1: ON PK Fc 102 Hz Gain -2.5 dB Q 2.00
Filter 2: ON PK Fc 142 Hz Gain -2.3 dB Q 2.00
Filter 3: ON PK Fc 252 Hz Gain -4.1 dB Q 1.00
Filter 4: ON PK Fc 505 Hz Gain -2.9 dB Q 1.36
Filter 5: ON PK Fc 963 Hz Gain -5.1 dB Q 1.00
Filter 6: ON PK Fc 2,107 Hz Gain -11.8 dB Q 1.54
Filter 7: ON PK Fc 2,135 Hz Gain 18.1 dB Q 1.00
Filter 8: ON PK Fc 3,350 Hz Gain -6.3 dB Q 2.29
Filter 9: ON PK Fc 4,315 Hz Gain -2.5 dB Q 9.77
Filter 10: ON PK Fc 5,100 Hz Gain -2.2 dB Q 7.00
Filter 11: ON PK Fc 5,773 Hz Gain 1.7 dB Q 5.00
Filter 12: ON PK Fc 6,657 Hz Gain -4.5 dB Q 2.80
Filter 13: ON PK Fc 9,372 Hz Gain -6.6 dB Q 4.07
Filter 14: ON PK Fc 11,420 Hz Gain 4.3 dB Q 4.09
Filter 15: ON PK Fc 13,000 Hz Gain 7.2 dB Q 1.58
Filter 16: ON PK Fc 19,500 Hz Gain -4.6 dB Q 1.20
Filter 17: ON PK Fc 19,988 Hz Gain -0.9 dB Q 6.00
[/spoiler] [spoiler title=’Bandwidth parametric’ style=’default’ collapse_link=’true’]Preamp: -7.7 dB

Filter: ON PK Fc 102 Hz Gain -2.5 dB BW Oct 0.714

Filter: ON PK Fc 142 Hz Gain -2.3 dB BW Oct 0.714

Filter: ON PK Fc 252 Hz Gain -4.1 dB BW Oct 1.3885

Filter: ON PK Fc 505 Hz Gain -2.9 dB BW Oct 1.0383

Filter: ON PK Fc 963 Hz Gain -5.1 dB BW Oct 1.3885

Filter: ON PK Fc 2107 Hz Gain -11.8 dB BW Oct 0.9211

Filter: ON PK Fc 2135 Hz Gain 18.1 dB BW Oct 1.3885

Filter: ON PK Fc 3350 Hz Gain -6.3 dB BW Oct 0.6251

Filter: ON PK Fc 4315 Hz Gain -2.5 dB BW Oct 0.1476

Filter: ON PK Fc 5100 Hz Gain -2.2 dB BW Oct 0.2059

Filter: ON PK Fc 5773 Hz Gain 1.7 dB BW Oct 0.2881

Filter: ON PK Fc 6657 Hz Gain -4.5 dB BW Oct 0.5125

Filter: ON PK Fc 9372 Hz Gain -6.6 dB BW Oct 0.3536

Filter: ON PK Fc 11420 Hz Gain 4.3 dB BW Oct 0.3519

Filter: ON PK Fc 13000 Hz Gain 7.2 dB BW Oct 0.8985

Filter: ON PK Fc 19500 Hz Gain -4.6 dB BW Oct 1.1699

Filter: ON PK Fc 19988 Hz Gain -0.9 dB BW Oct 0.2402[/spoiler]

How I calculated the EQ values

In Excel, I laid a log-scale graph over the HE400i’s frequency response, which in turn is laid over the target frequency response. I modeled points (frequency, volume) on both response curves and subtracted them to get EQ gain values as well as a properly compensated frequency response, which I imported into Room EQ Wizard to calculate parametric EQ settings.

Download the Equalizer APO config file and the Excel spreadsheet here.