Since it is measured on a rig, often those peaks will either be in a different area when on your own head. So you might accidentally be EQing the wrong way. As well some narrow dips are phase cancelations in which it doesn't matter if you try EQ it back, the dip will still be there regardless

EQ can change a lot, and completely transform a headphone. One thing though is that it's better to EQ with wider filters, as trying to EQ narrow peaks and dips can cause issues. So in that sense, you can EQ most headphones to have very similar sound signatures, but usually there's small details in the Frequency response that are harder or unable to be EQd.

Remember that the frequency response changes quite drastically on your own head, compared to what you see on a measurment rig. So even if you EQ two headphones to have an almost frequency response on a graph, on your own head the FR at your eardrum may be drastically different.

If you were to measure the response of your own ear, and then EQ the headphones to your own ear response, then you can get something much closer. This is one method that Harman used to blind test headphones, they would virtualize different headphones with one test headphone (as well as using the real ones), and they found the results of prefrence tests using virtual headphones were 95% similar to the results using the real headphones.

So there are a few things to dissect here. A number of years ago, there was a lot more emphasis on alternative measurments like impulse, square wave, CSD, ect. But over time it became much more clear that SPL frequency response is most of what you need when it comes to headphone measurments. Due to them being mostly minimum phase, time relevant measurments are most often consistent and predictable. So simplifying things to just frequency response removes a lot of confusion, and is more representative of audible differences when it comes to headphone measurments.

On to your point about speed. How fast a driver can respond to a signal, it's common to initially think about inertia and how mass causes some lag in motion, but when it comes to headphone drivers, they are so light and thin that most are capable well beyond what is required. Many drivers are capable of over 40khz, but the audible range is up to around 20khz at best. That means any thing within the audible range will be reproduced "fast enough". If it wasn't able to respond fast enough, you would see a drop in the frequency response and an increase in distortion. Similar to what you may see in some sub woofers when they try to play above their frequency range.

On to your point about playing multiple frequencies at once, it's good to look into fourier series. When multiple frequencies are played at once, the amplitude is all added together. So when there is a rise, the amplitude is added together, and if there is a rise in one frequency and a decrease in another frequency, it's subtracted. This means many different sound waves are able to be layered in a single motion, and your ear works as a fourier transform to separate the frequencies and phase from the single combined motion into its individual frequencies. So when playing multiple sounds at once, the driver can make seemingly simple motions, that contain all the frequencies needed to hear multiple sounds at once which is then separated into its frequencies at your inner ear and brain

It's just not really needed. With loudspeakers you're working in a different environment and having multiple drivers can be more beneficial. For headphones, the drivers are often small enough and light enough to reproduce all audible frequencies without issue, and they also work in a different type of environment and produce sound pressure differently than loudspeakers in an open air environment. XM4 probably isn't the best example of a headphone for comparison as they're just not tuned all that well

I guess so. The 600, 650, and 660s haven't come with the hard box for a few years now

On my review of them, I found that every couple seconds the group delay would have a spike where it would delay more than the rest, and then work it's way back, before having a spike again. As well, in the FR you would see a spike or dip in SPL when this happened as well. This was consistent with time, so if you measured it quickly, it would happen once, but if the sweep was much longer, you'd see repeating patterns of this. It's definitely something weird with the dac in it. As well, yeah the pitch seems to keep shifting

Just a baffle between the front and rear volume, with some paper between it

Try lowering between 4khz and 7khz. That range in Harman seems to have the most problems for people

Fair enough. It definitely does get confusing when terms are used differently by everyone

I think resolve lately refers to those terms as "subjective things that aren't easy to see in FR, but may be contained in FR"

No, this is something that's often misunderstood, but in real world use, you can't easily EQ one headphone to another without knowing how that headphone or IEM response on your own ear. Even if you could EQ two headphones to appear to have the same FR on a measurment rig, on your own head the FR at your eardrum can still be drastically different

This is part of why "detail" is a little disagreed upon in terms of definition.

Some define it as a property of the driver that reproduces things others can't, and others define it as parts of the treble that emphasizes smaller nuances that are always there, but either masked or not as pronounced in most other headphones

If I'm not using stock, I tend to use spinfit tips

If you want to try something else (that's budget but sounds good), try the Koss KSC75, or 7hz Salnotes zero

Semi-open may as well be open back. They don't isolate much.

So in headphones, yes frequency response at your eardrum (not what is seen on a FR graph), is in theory everything that matters. Given that distortion is below the audible threshold, and the headphones are operating in minimum phase.

The frequency response of a headphone affects the sound waves that are generated, and how they are shaped when combined. When it comes to "Technicalities", yes it can be linked back to FR, but not simply as something that you can point to one area and pick out. More how different frequencies are emphasized and what is affected by auditory masking.

That aside, there are a lot of outside factors that can affect what we hear or perceive, such as how the headphones feel, how spacious the cups are or how isolating they are.

Our senses are a mix of "simple" systems, that are filtered through our brain and can be changed by other senses, or interpretation

CSD will change with EQ in headphones. Since they are (most often) minimum phase. CSD is good for room measurements with loudspeakers, but for headphones it will tell you the same information as FR.

On a headphone CSD graph, if you see what could be interpreted as a "ringing," when you EQ the peak down, the "ringing" disappears as well

It may be easier if you compensate (flatten) the graph, as comparing curved lines is inherently harder. You can do this by pressing the little squiggle line next to the target on squig.link

You'll notice that once flattened, the S12 has more emphasis in the treble than the Zero.

One thing to note with these IEM graphs is the 8khz peak is a resonance from the coupler itself, and the following dip and secondary peak are also due to the coupler, so the treble above 8khz on these graphs are not always representative of what your hear in your own ear

The overall balance of the two IEMs. The treble boost of the S12 pro could tilt the tonal balance towards more treble emphasis, while the darker tone of the Zero could lead to a down tilt in the response making is sound more bass focused

Same situation. I'm only an hour out of Vancouver, but I never go into the city, but I want to go to the headphone bar eventually

Do you have the link? I can't find them on Amazon.ca Edir: Nevermind, I found it

The Harman research says to adjust bass to your liking. The bass shelf was originally there because that's what room acoustics do when you take flat speakers and put them in a normal room, which was the basis for the target. From that there was some adjustments based on different user groups for the amount of bass, and the current shelf is what 60% of listeners preferred, but the research also says that more "trained listeners" prefer less bass, and again you are supposed to adjust that to your preference.

People hyper focus on the bass, but the upper mids and treble is a big part of the Harman target. If you put the HD600 response on the Harman target and compensate it to the target, the HD600 looks very consistent with the target above the bass.

I wouldn't really call it v shaped. More of a downward tilt with an optional bass shelf.

So you're looking for something with less mids and more treble?