Thank you for your responses on this stuff, Robbo99999.
I'll take the last question above first, since it's one of the easier ones to answer (I think?)... There are a variety of reasons why you might want to compare the measurements between different rigs.
A. To verify and validate that the results are accurate. Reviewers and graphers routinely do this to try to figure out where there might be some noticeable errors or discrepancies in their setups and measurements. Even Amir does this with his spinorama plots, to try to compensate them and improve their accuracy. The same theory also applies to headphones.
I will also often use the measurements of several different sites to EQ my own headphones. And in order to do that, I have to figure some way of adapting the data from each of them, so the results are similar. Which is no small task. The diffuse field graphs, primarily in Oratory's graphing tool are my current graphs of choice though, because they're the easiest for me to relate to something fairly concrete. (Namely, a speaker's sound power response.) And because many of the other sites have simply dropped DF compensation or put it behind a paywall, sometimes in favor Harman compensation or another target of their choice that's similar but maybe also flatter in the bass.
B. Because standardization is a good thing. For starters, without some form of standardization, it's not really possible for users of disparate measurement systems to accurately compare and contrast their results. Standardization also makes it easier and faster though (time is money they say) for a wider audience to use and interpret a measurement system's results. If the measurements are more standardized, then users have to spend less time learning how to intepret a particular reviewer or grapher's plots. And can spend more of their time just comparing and analyzing the brightness, darkness, warmness, bassiness, sibilance, tonal balance, etc. of some different headphones. So it's alot more efficient and useful.
I don't know if you and others here have noticed this, Robbo99999. But it seems like there's been a somewhat growing movement in certain audio circles, and perhaps also among some ordinary Joe-audio types
against the use of measurements. And I think one possible reason for this could be the lack of standardization in measurements. Because the harder they are to read and interpret, the more frustrated people get. And the more likely they probably are to just throw up their hands, and say this is all meaningless!
Laugh if want, but some of these folks apparently have a pretty big following among some audio users and enthusiasts.
Reading graphs isn't particular easy either. There's probably only a tiny fraction of the headphone users out there who can actually make sense of most frequency response graphs. And really understand what they mean. And even many of the so-called experts on the subject are still in the dark about alot of stuff. (I think even Resolve might possibly concur with me on that.)
Standardizing the measurements in such a way that the data is more readable, usable and comprehensible to a variety of users, and more easily interpretable across the different measurement platforms would, I think, not only help alot more people with their buying decisions. But it might also help to put the brakes on some of the anti-measurement sentiment.
I've spent a good part of the last decade or so looking into this subject, for example, and I
still have some difficulty accurately pointing out to others what a neutral response looks like on both raw and also compensated plots! The Harman curve made some good steps towards answering those questions. But it really didn't go far enough in my opinion. And based on some recent comments from one or two of the key researchers at Harman, I think they also believe that there's probably still some more work to be done on this subject as well. (Which was actually somewhat of a relief to me.) This brings me to point number three...
C. If someone like Harman could ever come up with a truly neutral response, then the standardization of measurements between different rigs (via something like DF compensation) would make it alot easier to accurately translate or adapt that target response across a much wider variety of measurement platforms. Instead of having to use it on just one closed system like the GRAS 45C, or something else. And it would also save folks like Jaakko the trouble of having to figure out how to adapt the target to the measurements of several other different systems.
What if someone using a different measurement system, like, say the new HBK 5128, or something by Head Acoustics, came up with a
better and more
accurate target than the Harman curve. And then decided they didn't want to share it with the users of other measurement systems? I wonder how that would make all of the GRAS users feel? Because that wouldn't be very cool. And I suspect that many folks using systems other than GRAS probably feel similarly about the Harman curve.
Tyll Hertsens of Inner Fidelity was one of the key figures who promoted, publicized and supported Harman's work on a new target headphone response curve, through his articles and videos. He was even invited to Harman's reference room to do some in-ear measurements on his rig. The Head Acoustics system that Tyll was using was different than the system Harman was using though. So in the end, there was really no easy way for him to deploy the new target response curve (that he wrote so many loving articles about) for his own measurements.
I watched Tyll struggle with this problem for months and years. To find a way to make the target work correctly with his measurements. And I tried to also help out a little where I could. And also suggested using DF compensastion as a possible method of translation. But that idea was rebuffed by some of the "smarter" kids in the room. It was like watching someone trying to put a square peg into a round hole though. And it wasn't that enjoyable for him, I suspect, or for the rest of his readers.
I'm sure Tyll had other more important reasons for closing up shop, and leaving the profession. But I suspect that experience left a somewhat bitter taste in his mouth, after all the support he'd given to the folks at Harman... Water under the bridge as the say.
So standardizing the measurements would make this kind of thing more open and accessible to a wider variety of graphers. And consequently also to a wider variety of headphone manufacturers, and also consumers. I think that was actually Harman's original goal in the beginning. And why they made most of the research on the subject of their target public. But then somewhere along the way, the Harman target ended up becoming more of a "perk" for all the users who happened to own systems similar to Harman. And a bit more of a hurdle to get over for just about everyone else. Which was a bit of a shame.
I'm sure I'll think of some other good reasons to compare measurements as well. But since this post is already gettin gargantuan in size, I'll stop with those.
And maybe come back to this again another time.