Thanks to Solderdude's filter design (seriously, I didn't do any of this myself) I've been able to try a couple configurations with the intent of lowering the intensity of the HE-4's treble. This filter is merely a circuit of resistors, capacitors, and inductors.
The "full filter" essentially holds the 6-8kHz area in one place and raises the surrounding frequencies in order to remove the peak entirely (this peak isn't as evident on my measurement rig as it is on purrin's -- you may have to do some digging if you want to see his measurements). The full filter config is a little bright for my tastes, but it brings more upper mid/lower treble clarity.
If I "short" a couple components in the circuit, the filter merely cuts the hot treble and leaves everything else the same. This darker presentation is up my alley. The treble isn't affected enough to remove the essence of the HE-4 but it's enough to remove/reduce my need for EQ.
I really like the idea of a filter mod because it doesn't mechanically dampen the driver. Most often the easiest way to lower treble intensity is to put something between your ear and the driver (felt, toilet paper, microfiber cloth, etc.) but this improvement sometimes comes with the trade off of muffling the sound as a whole.
The filter isn't all perfect though, as it doesn't remove the driver's tendency for sibilance. Some things we are going to just have to deal with in the end. Either way, I'd like to think these could be used to "fix" many headphones -- and I believe Solderdude has made efforts to get that point across as well.
Anyway, I just figured I'd post some of my results. Not sure if this is something people are interested in or not. :rolleyes:
EDIT: Do not compare these measurements to my old measurements in this thread. Totally different measuring setups, totally different results.
