Note that many mods don't do too much to the FR (well, some smoothing out and extra subbass), both MrSpeaker's (adds some midbass) and Paradox. What they vastly improve are the resonances and fit.

For example, this is the latest precise Paradox EQ.
If it doesn't look very similar to "inverted" T50RP stock response, I don't know what does.
However, since they're extremely clean except perhaps slightly midbass, the equalization doesn't mess them up in the slightest.

Just wanted to share these T50RP measurements:

Frequency Response:



Distortion Right:



Distortion Left:



CSD Right:



CSD Left:



T50RP vs HD600:



In stock form, I think the T50RP relative dip between 2 kHz  up to 5 kHz is what makes it sound a bit odd to me.

Just wanted to share these T50RP measurements:

Thanks for sharing... let me share something with you 

I measured the same 'chunk' and am annoyed with the lack of highs extension.
15dB down around 3.5kHz !
They drop off quickly above 10kHz and at 20kHz they are already 20dB down !
Indeed it is what makes them sound 'weird' when compared to 'flatter' headphones.
The lack of highs extension is what bothers me most when compared to others.



Purple is stock T50RP (not entirely stock it has the familiar mechanical mods) NO fake Pinna.
Blue is what it can be (but not through mechanical mods)

When you measure the same headphone with the BMF kit you will find the dip around 3.5kHz is gone.
I think it is because the mic is closer to the driver and the Pinna alters the FR.

The chunk gets smaller if you use a fake Pinna around the microphone as well (I made one of malleable eraser).
When sweeping it with a tone you will find that the 'dip' isn't 15dB but smaller (about what it measures with a fake Pinna)
The dip seems really there and when compensated as the blue line it sounds incredible, nothing like a T50RP

It is my go-to headphone (the blue lined one)

B.T.W.
I REALLY dig the comparative plots you often make, with 'well known' headphones, it shows in a more direct way what to expect.

A lot of BMF's mods had those paper reflectors in there which I always felt made the treble feel weird and papery (if you'll excuse the pun).

For anyone who has disassembled the driver before, which parts of the diaphragm are able to move freely? (refer to below image)
http://farm5.static.flickr.com/4066/4517202697_1769828e23_b.jpg

Would leaving the T50RP "burning-in" overnight (playing a 30Hz sine wave at high volume, for example) possibly help loosen up any moving parts (based on above) or is it likely unneccesary?