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Hifiman Ananda Review (headphone)

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#44
I'm starting to form the hypothesis, that group delay (as well as frequency response; particularly around 8 kHz and possibly around 2 kHz - aka, the Blauert bands) is responsible for much of the out-of-head soundstage (or is it instrument separation? I dare not answer that question yet) phenomenon. To wit, compare the Focal Celestee with the Utopia, Ananda and HD800S:

Focal Celestee Group Delay Measurements.png Celestee: "soundstage is mostly whacked in the middle of your head"

Focal Utopia Group Delay Measurements.png Utopia: "You get a halo of sound about 25 to 30% outside of your head with very nice instrument separation and excellent clarity."

Hifiman Ananda Group Delay Measurements Open-back Planar headphone.png Ananda: 'You do get nice sensation of "speakers away from your ear"'

1608853778796.png HD800S: "What was remarkable and uncanny was separation of instruments."

I've played around with increasing and decreasing the 8 kHz peak^1 of the HD800 (not S), and have noticed, that the soundstage collapses when the peak is decreased; and increases when the peak is increased. I've also tried putting this peak on other headphones, with mixed results: though the soundstage might increase, an audible resonance peak is then detected. Clearly, frequency response alone isn't responsible for soundstage. I'm now suspecting, that the cause is reflections, as evidenced by group delay over specific frequency ranges. This also explains why fiddling with frequency response alters soundstage: as response changes, so does reflection intensity.

I'd love to further test this hypothesis with iems: I suspect, that they have no group delay at all, indicating no reflections, indicating a lack of soundstage. I'd also like to test whether or not simulating reflections and group delay, say by increasing reverb over specific ranges, increases soundstage. I tried this once, but the plugin I used was insufficiently precise. I wonder if the famed Smyth device does something like this....

Thoughts and opinions? I wish Axel Grell or other headphone designers were members of this forum: surely they have the knowledge we seek!

^1: Or is it a peak? If the frequency response is flat, but there are a tonne of reflections, would the frequency response curve show a peak where none exists? In such a case, the frequency response curve is not just measuring frequency response - but also reflections. Perhaps a free-field measurement could answer this question.
 
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sweetchaos

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#45
Apologies if this was explained in a prior post, but these graphs are showing the different EQ settings between Amir and Oratory/Jaakkopasanen, right?
Correct.

It all started when Amir was trying to explain the differences between his PEQ and Oratory's PEQ profile, for AKG K371, back in January 29.
So I simply imported Oratory's PEQ profile and made a gif to compare both.
People liked the idea, and here we are... :D
 
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charleski

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#46
@amirm I just noticed that rtings.com also measures group delay. The scales are quite different, but theirs still seems to be way better overall. Can these measurements be compared directly? https://www.rtings.com/headphones/1-4/graph#670/4014
That RTings group delay graph looks heavily smoothed, which makes it useless for detecting reflections. It also uses a radically different scale, amir's plot is only +/- 5ms, their's is ten times larger.
 

Resolve

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#47
I saw those too. As I noted in the review, no amount of pushing against the pads generated the sub-bass results they show. In addition, in listening tests the sub-bass is just not there. So I have good confidence in my measurements.

In addition I see a lot of smoothing in other measurements posted which get rid of a lot of the fine variations I show.
Just a note about this, pushing on the pads for these types of planars wouldn't necessarily yield a higher bass response, depending on FS behavior, however more representative coupling might. It actually looks like in your measurements you're seeing the rise from an air gap of some kind that's more related to coupling integrity than pad pressure or compression, which would then show the subsequent dropoff behavior you've observed here. I'm HIGHLY suspicious that this is the result of the ear and cheek simulators not being actual human heads (including both the 45CA and our 43AG) - meaning they don't have the same contours - and with these egg shaped HiFiMAN headphones you're bound to get some of that behavior showing up.

Granted, we don't have 5128s that might help with this, but if RTINGS still uses in ear mics to test coupling integrity then theirs would actually be representative for SOME human heads for that at least.
 

tential

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#48
Another review that will cause Shockwaves through the community. Almost feels like you do it on purpose.... Jk. I will look through comments to learn new ways of justifying why your conclusions are wrong that I will be able to apply to any review I don't like.

Well, I'm really interested in the he6se v2 now. Happy I held my wallet this long.
 
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#49
@amirm the bass bump and drop you have there is indicative of not getting a good seal. Its what happens when you pull the hifiman headphones away from your head to break the seal slightly (like how the SR1A, TC1266 or AKG K1000 are designed to be). Creates a big bass bump.
 

zepplock

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#50
That RTings group delay graph looks heavily smoothed, which makes it useless for detecting reflections. It also uses a radically different scale, amir's plot is only +/- 5ms, their's is ten times larger.
How much of group delay is perceived by brain/ears?
With channel imbalance it can be as low as 0.5db, with distortion I think it was 1% (not 100% sure on the last number).
 
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#51
Unexpected result. I listened to a bunch in the store and the Anandas easily sounded best to me (among the price range I still deem "sane", at least). Kind of surprised by the middling performance here :) I found the unEQ'ed sound to be quite good, myself.
Congratulation, you hit the bar where science is not everything. :)
 

Cahudson42

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#53
Perhaps we need to consider several different Distortion tests, rather than just the three SPL levels done now?
 

Helicopter

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#54
Thanks Amir. These have been high on my list for a while, and if there had been a recent and exceptional sale, I would have been another casualty. I already have LCD-X, so I don't need another efficient planar that only sounds good with EQ. Granted, these are cheaper, lighter, and are not as broken without EQ, but still, not a good compliment to what's already here... back to listening to HD800S :cool:
 

GDK

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#55
@amirm the bass bump and drop you have there is indicative of not getting a good seal. Its what happens when you pull the hifiman headphones away from your head to break the seal slightly (like how the SR1A, TC1266 or AKG K1000 are designed to be). Creates a big bass bump.
But the EQ Amir added supports the measurements.
 

Cahudson42

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#56
The DCA Aeon RT closed back test - no bump. Low distortion.
Better seal? What other possible test variations/differences??

So far, two HiFiman with 'unexpected' high distortion - the Ananda and the HE400i. One double-magnets, one single..
Need the rest..:)
 
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amirm

amirm

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Thread Starter #58
+1 to @antdroid's comment:

You didn't get a proper seal.
With such giant headphones, how do you know you are getting "proper seal?"

So there is no confusion, the pressure I put on the headphone was to close the one gap that was facing forward. That simply pushed the 40 Hz resonant peak higher and actually made the bass droop faster. The rest of the headphone sealed really well. Indeed you could move it around and it would make almost no difference. It couples quite well to the fixture.

Many of the measurements out there have unknown amount of coupling. Some are using a single cup measurement and by definition putting a lot of pressure on the one cup to seal (using mechanical pressure).

The ultimate test here is equalization. Adding the bass boost most definitely brought up the sub-bass to acceptable level. Without it, there is very little of it.
 
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#59
Throwing my hat into the ring to say that getting a proper seal on most Hifiman headphones is pretty easy and I don't hear any sub-bass roll-off. @amirm might have some issues with his placement methodology and this isn't the first time our data disagreed with each other with regards to seal integrity either.

At any case even if we assume Amir's measurements are 100% representative of real world performance (I don't), a roll-off under 30Hz isn't the end of the world considering that it's still relatively emphasised AT 30Hz and there's not a lot of data around 20Hz anyways. Significant for a sub, sure, not so much for headphones.
 
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amirm

amirm

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Thread Starter #60
At any case even if we assume Amir's measurements are 100% representative of real world performance (I don't), a roll-off under 30Hz isn't the end of the world considering that it's still relatively emphasised AT 30Hz and there's not a lot of data around 20Hz anyways.
I have a complete playlist of files with significant content between 20 and 40 Hz. This is why I discuss sub-bass performance almost all the time in my headphone reviews. It is an area that a good headphone can easily outperform even the largest tower speakers with flat response down to subsonics. It is an absolute delight when the headphone can reproduce such low bass. It is an entirely different animal than a sub in a room.
 
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