Reducing and Increasing Upper Midrange/Treble

How to Reduce Unwanted Upper Midrange/Treble Peaks (ca. 5-15 kHz range depending on iem)

by Jürgen Kraus and KopiOkaya

nozzle covered with micropore tape

This is done im most cases by adding micropore tape onto the nozzle:

  1. Cover 80-90% of the screen with a single strip of micropore tape or use two thinner strips and tape over in a cross-like manner. If this does not work…
  2. Remove screen with a needle, tape nozzle hole completely over with micropore tape and poke a hole near the edge. Why? Because a metal screen can be unpredictable and may introduce hardness/harshness. If this still does not do the job in rare cases…
  3. Stuff alcohol swabs down the nozzle for dampening. This is explained here.

Tip: Partial covering of the nozzle typically does not affect the bass.

Downside: if nozzle is covered too much, micropore can slow down the bass and make it “boomy” and/or compromise dynamics and soundstage in some earphones.

KZ ED3 as is and 95% micropore taped

Example on the right: 95% of screen taped over with 3M micropore tape removed an evil 6-7 kHz “sibilance” peak in a Knowledge Zenith ED3.

If this does not work perfectly well, try this: cover the nozzle 100%, then take a needle and poke a hole in the middle and four by the edges.

Another example is the TRN-VX. Covering ca. 80-90% with 2.5 mm square of 3M micropore tape resulted in 2-3 dB decrease in the upper midrange.

nozzle tape


How to Increase Treble

Lack of treble is an indication of poor driver dynamics and is hard to fix. It could also be intended to avoid an overly aggressive lower treble. In some cases, the lack of treble could be the dampening effect of a poorly selected nozzle screen.

As a first step, remove screen with a needle (you can store it attached to a strip of wax paper; it is glued and will typically stick if you put it back; if not use super glue). Remove dampening material such as foam from the nozzle if present. Listen without either or stick screen back onto the nozzle head.

If this has no success, you can also try the following — as advised by Slater:

  1. Increase the nozzle diameter
  2. Shorten the nozzle length
  3. Use a tip with a wide bore and short length

The short wide-bore tips worked wonders for my Sennheiser CX 5.00. The problem was that the nozzle was too thin for the Tennmak Whirlwinds. I thickened the nozzle with a few windings of the the universal micropore tape until the tip was holding firmly in place.

thickening the nozzle with micropore tape


The principles were published by James444. You find the original posts under “Published Mods“.
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  • Reducing and Increasing Upper Midrange/Treble 1

    Head-Fier since 2016. He has been known as “Otto Motor” to Head-Fiers, as “Dr. Schweinsgruber” to users and Youtubers, and as “Brause” to Super Best Audio Friends and the Headphone Community. - For the purpose of confusion, he decided to pose under his real name Jürgen Kraus (“JK”) from now on. - This is a hobby. In “real” life, Jürgen is a professional geologist operating his own petroleum-exploration consulting company Franconia Geoscience Ltd. (see ad in the footer) based in Calgary, Canada. He holds German and Canadian passports. Jürgen had a classical music education from childhood through high school in Germany and he has been following popular music developments since the late 1970s. His understanding of arts and crafts was influenced by Bauhaus pragmatism: “less is more” and “form follows function”.