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Sunday, March 25, 2012

Etymotic Research ER-4B

Finally- measurement data of Etymotic Research ER-4B, fully calibrated by the manufacturer, and additionally calibrated by me.

PRO: ER-4B is ideal for binaural material reproduction due to its extreme flatness. Perfectly falls within the ITU tolerance mask! No headphones can beat this IEM in terms of diffuse-field accuracy.

CON: While maintaining 90 dB SPL at 1 kHz, the frequency response drops down to 74 dB SPL at 17 kHz. This is due to the nature how balanced-armature drivers perform in the high frequency range, and Etymotic Research did their best to get the widest frequency response bandwidth possible, by effectively under-damping a pair of Knowles ED9689s.


  1. Thank you for this ER4B information.
    As a newbie, I have 3 questions:
    (1) in the Frequency-Response graph there are 2 colored curves(green & orange)that I assume correspond to Etymotic & your own measurments. But what does the GRAY curve correspond to?
    (2) in what apparatus is the Frequency-Response measurment made? A 2cc coupler ?
    (3) would it be possible to get a table of the RAW values upon which the curves are generated ?

    1. (1) Green: left // Red: Right // Gray: Raw
      (2) A pair of IEC 60318-4 occluded ear simulators
      (3) sure.

      20 86.85
      25 88.05
      31 88.79
      40 89.4
      50 89.85
      63 90.21
      80 90.48
      100 90.66
      125 90.78
      160 90.87
      200 90.92
      250 90.96
      315 90.99
      400 91.03
      500 91.1
      630 91.3
      800 92.04
      1000 93.88
      1250 96.75
      1600 99.6
      2000 102.56
      2500 105.47
      3150 105.33
      4000 104.11
      5000 101.75
      6300 96.93
      8000 95.76
      10000 100.45
      12500 100.7
      16000 100.63
      20000 63.85

  2. I have a pair of ER-4s headphones, I also have measured their frequency response/distortion and found approximately the same values [around 0.5%], any thoughts why the etymotics have higher distortion? I have a feeling it is a 'balanced armature' issue... Thanks!

    1. Indeed, a balanced armature transducer has higher distortion figure in general due to the nature of their unstable driving mechanism.

      Considering the fact that the movement of an armature itself retards magnetic reluctance of the entire circuit with increased tractive force, (must stay away from the magnet in order to maintain linearity) even with the same amount of current applied, higher distortion figure on the BA shall be expected in contrast to the case of a dynamic transducer.

      Moreover, higher input of current will end up with even more distortion:

      F ∝ i^2
      F = Tractive force
      i = Current in the coil

      Further research on compliance-controlling techniques will resolve the issue, I hope.

  3. Hi, would it be possible for you to repost the ER4B measurements with your new CSD, ETC/group delay plots as well? I think they'd be helpful to people who continue to appreciate its attributes, thanks!

  4. Hey Rin. I own Shure SE535s, and they sound bad unless I EQ them to add more treble. I'm thinking of buying Etymotic ER4Ss. Do you think the higher distortion of the Etymotics will sound noticeable?

    1. Distortion figure of SE535 and ER4 is pretty much the same.

  5. Which other iems (and headphones) you know come close in terms of diffuse-field response neutrality?
    I ownn many but the ER-4S is propably the closest to what I want in terms of frequency response.

    A higher-end version of the ER-4S would be all I need.