The AKG K371 still the one? I'm considering a closed back for work, though higher budget isn't out of the question.
The more I'm using it, the more I find the K371 problematic in many regards, between poor channel matching, inconsistent FR depending on position (the simple act of leaning slightly forwards changes the seal / FR for me), etc. And while at the "macro" level the FR makes sense, at least below 3kHz (above it's a mess), at the "micro" level it's wildly uneven.
I find it generally difficult to go back to regular closed backs after using the AirPods Max. Not that the latter sound particularly great to me (although I do prefer it to the K371, and actually think that measured
on my head it may actually track Harman's own target better, including in the ear canal gain region, where I'm getting a decent response, unlike on most GRAS measurements you'll see around - I'm not sure of it but I suspect that the APM's rather peculiar pivot mechanism may have a responsibility in that regard), but it's just a much more stable experience. Below 1kHz the response is most often rock solid (as it uses the ANC circuit to adjust the output in real time) with perfect channel matching and up to 4kHz or so there is no high-Q feature whatsoever making it very easy to EQ, unlike most other closed backs. Besides you get the benefit of ANC eliminating your own bodily noises (heart beat, chewing etc.) and of all the ANC over-ears I've tried so far it's only one which ANC "woosh" I find nearly fully tolerable.
In the graph below, above traces the APM's R and L channels as measured on my own head with in-concha mics, below the K371's R and L channels, averages of several realistic seatings. The dotted trace is the K371's right channel when I lean forward (and by that I just mean "looking at my computer on the table" kind of leaning forward, not the full Japanese greeting), which I think can be attributed to its hinge design lacking range of motion (I'm getting a lot more pressure at the front of my ears than at the back, leaning forwards slightly breaks the seal). The APM's response is rock solid except for truly edge cases (head
very significantly rotated left / right or 90° leaning forward), because its terrible pivot mechanism is a dumb idea that compromises seal in these situations vs. a traditional yoke that naturally applies even pressure around the ear without a need to spring load the cups. Basically both have very poorly designed headband to cup attachment systems, the difference is that the APM's still works for the most part on my head (on yours it may be different) and the ANC circuit does the heavy lifting to compensate for these troubles.
Don't look at the wiggles below 60Hz, it's just that I didn't run sweeps at a loud enough volume.
Also, don't look at the absolute values below 50-70Hz, I have no way of checking whether they're somewhat correct or not, only look at relative comparisons in that range.
I would not be surprised that the instability at lower frequencies is something that most people would actually experience with most closed backs, at least to some degree.
Using that experimental DIY probe mic :
https://www.head-fi.org/threads/how...guarantee-a-better-sound.958201/post-16405751
This is the sort of results I'm getting past 1kHz (important note : these results are
not valid for you, they just
illustrate my own experience of
my own samples on
my own head. Also, don't look at the absolute values, they're necessarily incorrect to some degree, only look at the relative values between headphones) :
In solid red the APM's right channel, in solid blue the K371's right channel, in solid green as a reference the HD650 with somewhat fresh, but broken in pads.
While I'm nowhere near as confident in my measurements with this probe past 1kHz on my own head with the K371 and APM as with the HD650 or HD560S - particularly above 4-5kHz where I'm seeing more seatings variation that I'd like, using "counter" EQ to validate these measurements make me feel that they are a lot, lot more representative of what I'm experiencing than the measurements I'm seeing online, of the APM in particular (sorry but if I'm adding +10dB at 4700Hz my ears would bleed :
https://www.rtings.com/headphones/1-4/graph#16092/4011, same applies to the ear canal gain region, applying +5dB at 3kHz with a low Q value I'd go deaf :
https://www.headphones.com/communit...rpods-max-review-best-sounding-anc-headphones - in both cases adjustments that are largely above threshold of audibility).
I believe that some of the variation between my experience and the measurements seen online may at least
partially come from the fact that both the APM and K371 are quite susceptible in the ear canal gain region to compression variation, which is what I've attempted to assess with the dotted red and blue traces, which represent the APM's and the K371's right channels with very slight compression applied to the cups to try to make them more evenly pressed around my ears. The APM's headband to cup attachment system in particular may pose issues with rigs such as the one used here, which while it features a pinna doesn't conform particularly well to the average human anatomy around the ear :
https://crinacle.com/2020/12/19/apple-airpods-max-review-the-audiophiles-perspective/ ? Also, I wouldn't be surprised to see quite a bit of variation across individuals using the same DIY methodology as above, so I feel that it's likely that your own experience may vary.
All that just to say that, given the option to PEQ the hell out of it, as I don't particularly love the response above 3-4kHz
on my own head (deficient around 4kHz, peaky and fatiguing above, albeit less so than what I experience with my K371), I'd rather use the APM than any other closed back I've tried. Without PEQ... I don't really like it, but the balance of its benefits vs. drawbacks make me reach for it quite often (as an iPhone user I have to use the cards I was dealt with...).
I think that while current ANC over-ears have significant drawbacks, the ANC feature is a very neat way of solving the sealing and FR instability issues that may frequently plague most closed back headphones. This is something that
@solderdude has tested several times :
https://diyaudioheaven.wordpress.com/headphones/measurements/brands-st-x/wh-1000x-m3/
https://diyaudioheaven.wordpress.com/headphones/measurements/bose/qc35-ii/
The K371 on the other hand is a pair of headphones which I can't really PEQ, if only because of poor channel matching and unstable FR. I still enjoy it for the price though and is there a decent alternative to it in that price range anyway ? I'm not sure of it.