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jlo

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I have an Iphone with AirPods Pro and I'm globally pleased with the sound quality and features but I'd like to share some remarks and questions :

What I like :
  • sound quality of Airpods Pro
  • Apple advanced features : Spatialize Stereo, Head tracking, Personnalised Spatial Audio
What I don't like :
  • ergonomics of Apple audio settings is poor with uncomprehensive terminology
  • settings are spread over unrelated menus
  • No on/off switch for « Personnalised Spatial Audio » so impossible to do valid comparisons
  • Spatialise Stereo adds some "unwanted" room reverberation in both fixed and headtracked modes (spatialisation itself is quite good)
What I'd like to know/confirm :
  • does Dolby Atmos deactivate « Spatialise Stereo » but keep HRTF of « Personnalised Spatial Audio » ?
  • Ear Tip Fit Test seems to be just a low frequency test : no LF correction is applied
  • which EQ preset is best to get a response near Harman target : maybe "Acoustic" ?
I also tried to clarify audio settings :

menus.jpg


If you have more informations, please let us know.
 
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Spatialise Stereo isn't a simple cross feed. It's using a generic HRTF with head tracking.

Still can't get over how good the system is. I ran through a 7.1.6 tone test & the accuracy of placement is amazing.
 
Spatialise Stereo isn't a simple cross feed. It's using a generic HRTF with head tracking.
Why do you think it is a generic HRTF ?
I hope that Apple is using the personalised HRTF, derived from head scanning : HRTF at +-30° ?
 
  • does Dolby Atmos deactivate « Spatialise Stereo » but keep HRTF of « Personnalised Spatial Audio » ?

Dolby Atmos is the content's format. Spatial Audio is Apple's terminology to talk about their renderer, which for compatible devices is a system-wide feature. Any time the system-wide renderer is active, whether it's to binauralise a stereo, 5.1, or a Dolby Atmos file, Spatial Audio is activated. The personalised profile is used if available, whenever the system-wide Spatial Audio renderer is active (or with third party headphones in Logic Pro, but that's an exception).

  • Ear Tip Fit Test seems to be just a low frequency test : no LF correction is applied

The APP2 continuously adjust the FR up to 3-5kHz or so to try to deliver a stable FR across users or fit (including leakage), regardless of the mode they're in. Active headphones with a feedback control loop (ANC) can mitigate leakage / fit issues already up to a certain frequency (typically 300-800Hz), but the APP2 use additional systems on top of it to reduce potential errors (notably parasitic leakage), extend their capability to actively adjust the response at higher frequencies, and be able to do so when the feedback control loop is off (ANC off).

The ear tip fit test simply tests whether or not the amount of leakage is beyond the threshold that Apple considers the limit of what the APP2's active systems can handle to deliver the intended experience, but the APP2's systems already are very capable (compared to other IEMs they can handle a lot of leakage while still being able to deliver a reasonable FR).

  • which EQ preset is best to get a response near Harman target : maybe "Acoustic" ?

Perhaps that rather depends on which Harman target you're looking for, which volume level are you listening them at (the APP2 adjust the FR depending on volume), exactly how their active systems behave when they're seated in your own ears, the length of your own ear canal (which I believe for IEMs is a significant contributor to the eardrum HRTF / HPTF mismatch for some individuals, and not just because of the length mode resonance between 6-10kHz, which would require you to interpret graphs a bit differently past 1kHz), etc.

At low frequencies at least, if what you want to emulate is the Harman OE, I'd leave the Music app EQ off. It's quite close to begin with.
 
The personalised profile is used if available, whenever the system-wide Spatial Audio renderer is active
Thanks. Where did you get this info or did you measure it ?
The ear tip fit test simply tests whether or not the amount of leakage is beyond the threshold that Apple considers the limit of what the APP2's active systems can handle to deliver the intended experience
OK for this confirmation.
At low frequencies at least, if what you want to emulate is the Harman OE, I'd leave the Music app EQ off. It's quite close to begin with.
I did not do any measurement but I think you are right : EQ Off gives a small boost at low frequencies that may be similar to Harman target.
EQ "acoustic" seems to have a flatter response in LF.

Thanks a lot for those valuable infos.
 
Thanks. Where did you get this info or did you measure it ?

The system-wide renderer doesn't really have a way to select which content will receive the application of the personalised profile or not, as long as it follows some specific API implementations to enable Spatial Audio in the first place. If so they all go through the same pipeline and will be treated the same.

When I say "system-wide", I mean whenever you see this interface come up with compatible devices when content is playing (whether the content is stereo, 5.1, 7.1 or Dolby Atmos, etc.) :
Screenshot 2024-06-13 at 09.40.11.png


Games are a bit different though.
 
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