I've seen drastically different measurements from this headphones. I have not tried one yet.
Crinacle with GRAS measured identical response. On B&K 4128c it's a different story.
So this time it's not only the test equipment itself is different but also the headphones are dynamically eqing on the fly according to the pinna.
I don't think so. It uses only a single microphone in front of the driver like most other ANC headphones and the optical sensor is your typical basic one, and besides it sits behind the ear lobe (
https://www.52audio.com/archives/67123.html). So it has no way of knowing whatsoever what is the shape of your pinna
.
I think that if it were able to compensate for pinna variation it would also compensate for positional variation during spatial averaging which isn't the case :
Adaptive EQ seems to only work up to 800Hz or so, like most ANC headphones with a feedback mechanism.
While I can't talk about others' experience, my own experience with them does not match most measurements I've seen online. If I were to apply Amir's recommended EQ, they'd sound definitely very wrong to me.
The limited measurements I can make of them
on my own head, comparing them in relative terms with other headphones, makes it plainly apparent why : I just don't get anywhere near the amount of ear canal gain deficiency as what can be seen in most measurements of the APM online - all of which show some degree of deficiency in that area, but are also all over the place in terms of its magnitude - and I can only notice that sometimes even simply changing the pinna (ceteris paribus ? I'm not sure) seemed to result in quite a big difference
:
Using this little guy, calibrated "flat" against a UMIK-1 with a speaker in near filed conditions :
And comparing my APMs with the HD650 (fresh but broken in pads), HD560S, and K371, I get this :
Traces obtained during the same session (the microphone wasn't moved), APM in orange, HD650 in red, HD560S in blue, K371 in turquoise.
A legitimate question would be : how confident can I be that these traces are providing decent information ? The long boring answer would compare all of these :
and involve nebulous graphs like these :
But the TLDR is that
in the ear canal gain region (1-4kHz) I'm tempted to think that, for
relative evaluations only, a 1dB inexactitude is a decent allowance
for the APM, HD650, HD560S (less so for the K371 which has more seatings to seatings variation).
Please don't look at the absolute values, they're inaccurate - only the
relative values between HPs. And don't over-interpret them (it depends on both the specific headphones and for which specific part of the FR spectrum, and is influenced by numerous factors).
So in general, for me, the APM tends to track somewhat well the HD650 up to around 2.5-3kHz, and then veers off a little lower around 3.5kHz. I also find it deficient, but rather specifically at around 4kHz, and certainly not by the tune of 8-10dB.
The only hypothesis I could draw is that the acoustic design may be a little bit more sensitive to pad compression / front volume "volume" than others. The way the APM (or most other headphones for that matter) sit on my head and relative to my ears has little in common with how it sits on a GRAS hammerhead style fixture and while that may not cause a problem with other designs perhaps it might with the APM.
During another session I tried to compare it as it sits naturally on my head with how it performs with a little bit of extra force at the bottom rear of my ears to more evenly balance out how the pads are compressed, as its headband to cup pivot design doesn't work well on my head to naturally evenly compress the pads. I noticed that it changed the response in the 1-3kHz area independently of what happens below 1kHz and between 3-5kHz :
Compressing it a little bit and making the pad's compression a bit more even around the ears seemed to improve the response a little bit between 1 and 3kHz and eliminated a null that occurred at around 5700Hz.
So I'm not certain what to make of it to be honest, other than being quite certain that my own experience of them, while not being particularly enjoyable (I don't particularly care for the response above 3kHz), isn't well aligned with how some (most) measurements I've seen online portray them. And I wouldn't be surprised to learn that individual experiences may vary quite a lot more than with some other HPs.