Not to derail... For all of this, I greatly appreciate you passing along Conover's article, also the forum posts on solderdude and BMF's testing rigs, though I will be honest and admit it is not quite up to the level of specifications and accuracy I am aiming for. I read through John Conover's documentation for his headphone measurement system and while his conclusions are generally thorough and well-researched, there have been findings in recent years on which he has missed several key points. For example, he claims that while differences in output impedance may make minute differences in headphone frequency response on the order of a fraction of a decibel, these are inaudible. In the first place, this ignores the importance of a damping factor in other quantifiable areas, such as impulse response, which has to my ears a clearly audible effect in the temporal domain (generally less "sonic fog", as it were, with higher damping factors and near-zero output impedance). Secondly, in the case of very high output impedance, this ignores the effect of the increase of noise as a product of current and impedance though admittedly its impact is generally insignificant in this metric. Finally, his measurement system utilizes non-ideal materials along the sound wave propagation path to the microphone in that the headphone and canal and headphone docking materials themselves are not of an acoustic resonance or natural geometry which are approaching those of the human auditory system. In my DIY project, I would like to create a very ideal system that models as closely as possible the human auditory system so I will need a bit more than what these projects offer. Nonetheless, these resources will serve as a wonderfully rich resource and starting point as I continue my search in incorporating design elements from binaural recording and HATS systems in blueprinting my headphone measurement system.
More neutral, less grainy, less obvious you're listening to a tiny dynamic speaker. I was just talking about the physical property of openness because SHAMuuu was talking about removing materials to make the DT990 more open.
