[ubs28]

Green = Shure SRH 1840
Red = Sennheiser HD 800
 
 

So the HD 800 has a mid-bass boost and a dip at the mid range. Both the HD 800 and Shure SRH 1840 seems to roll off the sub bass, but since the HD 800 has a mid-bass boost, it is not as apparent from the frequency graph. 
 
The HD 800 doesn't look as flat as headphones like the Shure SRH 1840. It is a bit coloured with boosted and dipped frequencies. 

 

[shadow419]

Look up equal-loudness contours (Fletcher-Munson curves), and how that relates to how we perceive sound.

 

[ubs28]

  Look up equal-loudness contours (Fletcher-Munson curves), and how that relates to how we perceive sound.

 
Thanks for this info. I never heard about this curve. Learned something new today
 
The best neutral sounding headphone would be a rolled off bass at around 100 hz and a small boost at the mid range with a small dip at 1000 hz. The Sennheiser HD 800 doesn't do that with its mid bass boost and dipped 3000 hz mids (this should be boosted for a neutral sound ).
 
edit: The HD800 should also roll off the high frequencies more for a neutral sound based on these graphs.

 

[MacedonianHero]

  Green = Shure SRH 1840
Red = Sennheiser HD 800
 
 

So the HD 800 has a mid-bass boost and a dip at the mid range. Both the HD 800 and Shure SRH 1840 seems to roll off the sub bass, but since the HD 800 has a mid-bass boost, it is not as apparent from the frequency graph. 
 
The HD 800 doesn't look as flat as headphones like the Shure SRH 1840. It is a bit coloured with boosted and dipped frequencies. 

 
Have you heard these headphones?

 

[TMRaven]

Equal loudness contours don't correlate to how headphones should be measured.  What you might look into is HRTF and how different measurement schematics deal with it via different compensations.
 
What's neutral for headroom/innerfidelity's graphs will show the headphones to have a little dip in the upper mids.  I havn't heard the 1840 but I reckon it would sound tinny based off those measurements.  Too much 2-3ish khz will come off as tinny sounding.

 

[MacedonianHero]

  Equal loudness contours don't correlate to how headphones should be measured.  What you might look into is HRTF and how different measurement schematics deal with it via different compensations.
 
What's neutral for headroom/innerfidelity's graphs will show the headphones to have a little dip in the upper mids.  I havn't heard the 1840 but I reckon it would sound tinny based off those measurements.  Too much 2-3ish khz will come off as tinny sounding.

Good guess, cause that's how they sound to my ears...and the bass is certainly lacking and if one tries to crank up the volume, the distortion really kicks in hard.

 

[Fugue]

You might try actually listening to them rather than judging them by a graph. Just sayin'.

 

[earformance]

Absolutely right. I've owned many headphones, but none of them was as transparent and natural as HD800.
Analysing and comparison graphs like you do is like compare 2 apples without tasting. In that case i always choose the uglier one 'cos it tastes much better

 

[vid]

  Analysing and comparison graphs like you do is like compare 2 apples without tasting. In that case i always choose the uglier one 'cos it tastes much better

 
If you had very specific data on both apples, as you do for headphones here, you might very much not need to taste them to have an idea which would be more to your liking. They could be measured and rated for juiciness, there could be a sourness/sweetness rating as well, something about their texture, etc.

 

[Blackmore]

It is pretty simple, neutral = dull, of a color / colorless, so, are HD800 like that? Definitely not. You may find them most natural or transparent, but that’s something different than neutral. There are only one pair of headphones I tried that I can call neutral and these are Grado HP1000, but I have no idea how they will measure.

 

[vid]

I'd say it's more like, neutral = original. You then see the problem of calling it dull.
 
Natural is probably a neutral midrange by necessity.