[Sheerglory]

Hi there everyone, I'm a bit of a lurker, but I have been around for a while. I just haven't felt the need to create an account as of yet.
 
I have found a strange thing when equalizing my headphones with Equalizer APO across the whole system. I realize that it isn't a system problem, but more of a potential strange occurrence with physics. I was wondering if anyone else has found the same thing when equalizing their headphones. The frequencies between 8200 and 8600hz seem to only be consistent if the headphones are positioned in an optimal way.
 
My setup is AKG K702's with a Tube Magic D1 DAC and Amp running from my computer. When equalizing consecutive days with Sine Gen, I noticed that a few frequencies in this range would swap ears and come in and out, then the next day, after apparently fixing it, it would happen again, and never cease. This is a strange phenomenon which I have discovered and it seems that if the headphones are positioned exactly right then the transition is smooth. It does not happen with any other frequencies higher or lower, just those ones. I thought it must have been a problem with my rig, but my friend reported it also when flattening his M50's.
 
The positioning seems to be the reason for the change. Does anyone have any ideas on how to combat this? It's difficulty to always put the headphones on the exact same way every time to ensure a smooth transition over these frequencies. Has anyone else experienced this?

 

[ProtegeManiac]

  The frequencies between 8200 and 8600hz seem to only be consistent if the headphones are positioned in an optimal way.

 

Not specifically that range but how the drivers are positioned relative to the ear canals can affect frequency response; that's why some for example have angled earpads (K7xx) or driver mounts (HD800, T1, etc) that mimic speaker toe-in angles, reducing glare and the extremes of headphone listening (too strong, too forward L-C-R that has weaker signals in-between). Other headphones don't have such chassis designs but still place the driver ahead of the ear canals a little bit, like on the HD600, and I actually do push it forward a bit more folding the tips of my earlobes slightly forward). The usual way of wearing Grados brings up all those imaging issues I mentioned, which some "love" as the Grado signature sound, but like how "signature" is actually just the result of compromises, that's the result of the simpler construction process and parts fabrication, particularly their earpads.

 

Another thing with headphones that you get in place of "room modes" that speakers have is earpad wear. The frequency response is affected the more worn out the earpads get since they also move closer to the ears as they get compressed and hold that shape over time. An HD600 on a brand spankin' new set of earpads is a lot closer to the HD800 in tone than how people typically describe the sound, likely because they don't take this into account. Many of the impressions for example take place in a meet where several people might have put an accumulated time of perhaps several hours throughout the day, and at some point - particularly if worn too tight for long enough - the sound is exactly how most people describe them here, and that's why there are a lot of people who owned them long enough disagree with that, all because these have owned them with enough commitment to at some point get new earpads.