Audio EQ Settings

Since I went to the dark side, and started using gentle parametric EQ to correct the FR of headphones & speakers closer to neutral, I want to collect the EQ settings here. My general philosophy is to make subtle corrections. FR response deviations are often related to other forms of distortion like phase or ringing. Amplitude corrections big enough to restore completely flat response may exacerbate those other factors. Thus I stick to subtle, gentle corrections that bring it closer to neutral yet preserve the original character of the sound, short of restoring perfectly flat response.

When boosting levels, remember to apply an equal reduction in overall gain to avoid clipping. Take the biggest amplitude boost at any frequency and cut by that amount. This is in the voltage (not power) domain, so dB = 20 * log(V1/V2). That is, cutting the amplitude in half is 6 dB (not 3).

For example, if you apply +2.5 dB @ 4.5 kHz, then you must reduce overall gain by 2.5 dB, which is a gain ratio of 1 / (10^(2.5/20)) = 74.98%. Or just use 74%. When it comes to gain ratio, to avoid clipping, lower is safer. So always round down (truncate the decimal).

Also, consider that boosts more than 3 dB can overwhelm the transducer, especially in the bass. You don’t want to restore linear frequency response only to have sloppy bloated sound quality. I keep adjustments to 3 dB or less. Furthermore, use parametric EQ with the most gentle slopes (broadest bandwidth) you can. The steeper the slope, the more phase distortion. The key to transparency is small corrections with gentle slopes. Don’t make the cure worse than the disease!

Updated: Jan 2019 with Room EQ Wizard for the speakers.

Sennheiser HD-580

Characteristic FR: flat down to 50Hz, then roll off bass at about 6 dB per octave. Gentle dip of about 5 dB between 3500 and 9000 Hz. Narrower dip of about 6 dB between 10 and 17 kHz.

Parametric EQ Correction:

  • +3 dB @ 25 Hz, Q=0.67 (2 octaves wide — 1 each side)
  • +3 dB @ 14 kHz, Q=1.3 (slightly under 1 octave wide)
  • Gain: -3 dB = 0.708 = 70%

Subjective Difference:

This simple EQ transforms the venerable HD-580 giving it a fatter, smoother sound. Deeper bass extension without impacting mid-bass and linearity. Slightly crisper transients and “air”. Even though the midrange is untouched, it sounds a touch more open, less boxy.

Audeze LCD-2

Characteristic FR: flat from zero to about 2 kHz. Smooth dip of about 7 dB from 2k to 9k. Mostly flat again from 9k on up.

Parametric EQ Correction:

  • +3 dB @ 4500 Hz, Q=0.67 (2 octaves wide — 1 on each side)
  • Gain: -3 dB = 0.708 = 70%

Subjective Difference:

Normally the LCD-2 sounds very natural, yet soft like listening from the 5th instead of 1st row, and correspondingly less detailed. This EQ brings the LCD-2 back to the 2nd row and restores some lost detail, but without affecting its natural voicing. It transforms the LCD-2 into the perfect headphone!

The 2016 and later LCD-2 are a touch brighter and need less EQ. Say 2 dB for these, and 3 dB for the 2014 model. CSD plots show the LCD series headphone is pretty clean, but has some ringing around 4-5 kHz, which is the trough of their natural response curve, so you don’t want to boost this freq too much.

Magnepan 3.6/R

Characteristic FR: depends on the room. My listening room has floor-to-ceiling tube traps 2′ diameter in corners behind the listener and 4″ thick RPG acoustic foam on the wall behind the listener. This EQ is busier than the headphones, which is unavoidable with in-room speakers, though I still managed to keep the rates gentle.

Parametric EQ Correction (old):

  • +3 @ 31.7, 1/3 octave: 25 – 40
  • +4 @ 54.1, 1/3 octave: 41 – 65
  • -5 @ 100, 1/3 octave: 79-126
  • +6 @ 182, 1/4 octave: 153-216
  • +3.5 @ 389, 3/4 octave: 231 – 654
  • +3 @ 3435, 1 octave: 1717 – 6870
  • Gain: -6 dB = 0.501 = 50%

New (as of Feb 2016).

  • +3 @ 31.7, 1/3 octave: 25 – 40
  • +6 @ 54.1, 1/3 octave: 41 – 65
  • -5.5 @ 106, 1/3 octave: 84-134
  • +6 @ 182, 1/4 octave: 153-216
  • +3 @ 313, 1/4 octave: 263-372
  • +3 @ 480, 1/4 octave: 403-570
  • -3 @ 632, 1/7 octave: 572-698
  • +3 @ 1099, 1/2 octave: 777-1534
  • +3 @ 3206, 1/2 octave: 2267-4534
  • -1 @ 8933, 3/4 octave: 5312-15023
  • Gain: -6 dB = 0.501 = 50%

With these settings, the Maggies drop 1.5 dB per octave from 40 Hz to 20 kHz, and they measure within 4 dB of flat along this line. The bass rolls off below 40 hz, but deep bass is still there: 30 Hz is at the same level as 2 kHz, and 25 Hz is audible. Here’s the curve: