MrSpeakers Aeon Flow Open Planar Magnetic Headphones Measurements

Click on graphs image to download .pdf for closer inspection.

I need to say right off the bat that I had a hell of a time with noise on my THD+noise plots during this measurement section. I retried the measurement numerous times and was able to make some improvements. The best take and probably most indicative plot was on the no filter measurements. I'm only going to show the image of the "one notch filter" plots image above as they're so similar. You can find all the plots here: no filter; black foam filter; one notch filter; two notch filter.

Here's an overlay of averaged raw responses for all four configurations.


In my measurements the biggest changes were in the 2-10kHz region and at the 19kHz peak.

Back to my analysis of the "one notch filter" measurements shown at the top of the page:

Raw frequency response plots show a well extended and essentially flat bass below 60Hz. the discontinuity between 60-100Hz is likely "pad bounce," which I find in audible in headphones as a rule.

From 100Hz to 1.2kHz response is a linear but gently falling about 5dB overall. I think this part of the response is responsible for the very slightly muffled or veiled character heard in listening.

Response above 1.2kHz rises to a peak 10dB higher peak at 4kHz. Usually I like to see this peak at 3-3.5kHz, but had no issues with the slightly higher frequency peak. Though the target response would have the peak 13-15dB higher than baseline, I do find 10dB peaks perfectly acceptable...and maybe even preferable given my tendencies towards a warmer sounding headphone.

The drop from 4kHz to 7kHz again is a warmer than neutral respons, but not unusual. The spike at 9kHz is somewhat variable with the different filters and is likely responsible for the slightly sparkly response that can be nicely modulated with the various filters. The peak is also common to most of my measurements and is likely an ear canal resonance that is not heard as a peak in listening. I sure didn't.

30Hz squarewave does exhibit an odd swayback shape and is likely due to the sloped midrange response and pad bounce. This may also be indicative of the slight "bloom" I heard in listening. Note the waveform remains above zero until the end indicating excellent bass extension.

300Hz squarewave overshoot is substantially lower than I would like to see, and rather surprising to me as I heard these cans as having a well balanced and clear treble. The gentle shoulder subsequent to the peak is indicative of a moderately warm headphone. Though a tad noisy, there is no significant ringing or other features, and is quite clean for a planar magnetic.

Impulse response shows a very clean initial transient with little subsequent ringing compared to most planar magnetic headphones.

THD+noise (ignoring the noise artifacts) is very low. I heard zero sense of hardness in these headphones; everything was very easy to listen to.

Impedance interestingly shows a little rise in the low and high frequencies, which is quite unusual in a planar magnetic headphone. Nominal impedance is 11 Ohms.

Isolation plot does show about -10dB of isolation in the higher frequencies. Quite unusual for an open headphone.

Needing around 140mVrms (averaged over the four plots) this is a fairly easy to drive planar magnetic and will achieve resonably loud levels from a portable device.

The measurements are good...but not nearly as good as the Aeon Flow Open sounds. Funny how that happens. Live and learn.

MrSpeakers Headphone Products
3366 Kurtz Street

Rthomas's picture

Hi Tyll,

Thanks for the review, finally it looks like we have a reasonably priced upgrade to the classic Sennheisers without any glaring weaknesses. It only took 14 years :D

A few years ago you did an AMA on Reddit where you said the point of diminishing returns was around $300.

Now that 'Mid Fi' has moved up to $500 to $1000 and TOTL cans are at $4000 how close does something like the Aeon Open get to the likes of the Utopia and LCD-4? My guess is that the Bass on the Aeon goes lower than the Utopia and the Aeon's treble is likely to be more even than the LCD4.

Considering these factors are these outrageously priced TOTLS $3200 better or $200 better at the most? :D

MattTCG's picture

I see my name referenced at the end of this well written and accurate review. I like this. Makes me feel fuzzy and warm:-) This is a great time to be in the hobby. I hope to see more manufacturers putting out sub $1k products that offer this level of performance and enjoyment with the build quality to back up the purchase.

veggieboy2001's picture

A great review as always Tyll, thank you!

was curious of your take on how easy these are to drive...Most planars seem to crave power, are these best with a beastly amp,or can you get away with less juice? I'm sure the scale well with the better you feed them.

Thanks again!

coastman25's picture

If the nearest rival to these phones in terms of sound quality are the HD600's which currently sell at $240.00 ie a third of the price of the Mr Speakers then a better case than this review needs to be made to justify buying them!
I still do not understand your obsession with reviewing either exotic or expensive headphones. I could never justify spending more than $300.00 myself on a pair of headphones, because to enjoy hifi quality listening you do not need to.
Others will have either a lower of higher bar but there are loads of good quality headphones within the more affordable range of $100 - $500, which you seem to ignore these days.

Vinhcomputer's picture

HD600 is $400 MSRP though the street price is much lower and this Aeon Flow is $800 MSRP with much better bass extension, look, material, case included, blah blah with some trade off. Let's wait and see what street price for these Aeon will be. Besides, HD600s are mass produced in a much bigger scale than these just released Aeons.
But right now, HD600 is a no-brainer choice in street price and Aeon Flow is mostly for enthusiasts.

seppukusword's picture

I have both headphones you mention along with the Monolith M1060 all running custom cables with XLR balanced connections to a Jotunheim and I find it intriguing how someone can compare the sound from two completely different approaches to the end result. The Aeon Open outperform the HD600 in every possible way, except for perhaps soundstage. The HD600, for example, have zero bass capability vs the AEon's. Do you have both as well? Interested in your thoughts.

What ae you powering your cans with to do the comparison?

Vinhcomputer's picture

(somehow my previous comment only show the subject after saving so here I'm posting it again).
The HD600 is $400 in MSRP though the street price is (much) lower than that, and the Aeon is $800 in MSRP with much better bass extension, better look, material, case included, etc. with some trade off. Let's wait and see what street price will the Aeon be.
Besides, HD600 is mass produced in much bigger scale than the just released Aeon Flow so if the Aeon is well received by customers then its cost will be lower.
However, right now, the HD600 is a no-brainer choice due to its street price/performance and the Aeon is only for enthusiasts with fat wallet.
What people hope to see soon is maybe a Massdropped Aeon :).

Core's picture

“I still do not understand your obsession with reviewing either exotic or expensive headphones.”

InnerFidelity is for audiophiles by audiophiles. There will be twenty-two open circumaural headphones on the wall of fame—including the retired ones—that InnerFidelity labels as $299 to $5 250. The number of open circumaural headphones less than $299? A big fat juicy zero. So your chances of convincing Tyll to review more headphones that cost $100 to $298 are about the same as my chances of convincing the Nobel Foundation to award the Nobel Peace Prize to Kim Jong-un.

coastman25's picture

I did not know being an audiophile had a price tag that is because it does not!
Even the great Tyll, Nobel Prize pending has often said that the audiophile headphone world for him starts around something like the HD 600 combined with a bottleneck amp total cost just over $500!!! Others may have either a lower or higher starting point. I am happy to agree with Tyll.
In regards to the “Wall of Fame issue” Tyll said this in his blog dated, Mar 30, 2016.
“My general principles so far is that for each category page I need one or two headphones in each price range that I feel are the best performers. Generally speaking, I see the price ranges as: Under $100; $100-$300; $300-$600; $600-$1000; and $1000+" and
“Another problem with this WoF page is that it's missing any headphone entry for headphones less than $299, and there are no headphones between the $399 HD 600 and $1499 Ether”
He then made a plea to readers for suggestions “what headphones do you think I should consider for these empty price ranges?".
I along with many others I responded. There are plenty of audiophile quality headphones available in these price bands I think you will find.

Core's picture

I agree that there are good open circumaural headphones that cost less than $300. But I still believe that Tyll is mostly interested in reviewing the ones that cost about $800 or more. But even if Tyll reviews a steady stream of headphones that cost $2000 or more, I shall not be upset. Because this site is for audiophiles.

You may not believe it, but being an audiophile does have a price tag. That tag might say $300 or $100 for you. But for many other audiophiles, that tag is more likely to say $2000 or $5000 or—O my sweet Jesus—$55 000. And I do not think Tyll has an obsession with reviewing expensive headphones. I think Tyll might be reviewing headphones that he believes many visitors to his website might be interested in buying.

coastman25's picture

The innerfidelity website is owned by TEN: The Enthusiast Network part of the Sports & Entertainment Home Tech Group. Tyll Hertsens is merely a contributor.
You can believe what you like, whilst the rest of us live in the real world.

SoapBox Sound's picture

Yes, I totally agree with you.

Similarly, I wish car magazines would STOP running articles and reviews of Corvettes, McLarens, M-Series BMWs, and the ilk.

After all, my 1981 Dodge Aries was Motor Trend's Car Of The Year; don't tell me that the Porsche 911 GT2 RS that just ran Nurburgring 6:47.3 is better than a K-Car.

coastman25's picture

Speed isn't everything when it comes to cars!
A Porsche 911 GT2 RS is just another car in a traffic jam only burning more fuel.

Core's picture

The Enthusiast Network also owns Stereophile. If you think the headphones reviewed by Tyll are expensive, what is your opinion of the prices of devices reviewed at Stereophile? Is it possible that both of these websites are targeting the same individuals? Is it possible that Tyll’s boss asked him to put a heavy emphasis on reviewing expensive, very expensive, and extremely expensive devices? Just like at Stereophile?

Once in a while, Tyll will review inexpensive or moderately priced headphones. But I think the vast majority of headphones reviewed by Tyll will continue to be expensive, very expensive, or extremely expensive. Real world? No. What the typical audiophile is going to buy? Yes.

Vinhcomputer's picture

@coastman25: Could you please list top 10 headphones/earphones about $300 or less (the street price of HD600/650) that haven't been measured by Tyll so people can vote and help him choose some pairs to measure or review? I'm also very interested in that. Let's set aside build quality for that price tag though.
I believe that true engineering gems can only be found in moderate to low price things since even novice can create somewhat better things in some aspects with exponential increase in price. Masters put full pride in their work so they don't do that kind of thing.

coastman25's picture

I think this is up to Tyll. If he wants he can ask his readers for suggestions. However someone like Tyll who attends many shows and is well versed in the headphone world will have no lack of possible contenders. Its his Blog so up to him and the owners of the site I guess.

seppukusword's picture

I agree 100%. If you want budget headphone ratings, there are plenty of sites for those. It's not worth the energy or time to do a full review and measurements on low quality closed cans we all know do what they do.

I have the Aeon Opens and find it amazing how people prejudice a headphone because of a price. If anyone things the Aeons are overpriced, listen to them on a Jotunheim with balanced XLR cables and you'll no ever say that again!

Martin.'s picture

I wonder how these do against the Elear? Seeing as his review for the Elears was full of praise, maybe they are worth the extra 200 bucks? Maybe the Aeon open are easier to drive?

dpippel's picture

Great review Tyll, and thanks as always for your opinion. Speaking of which, any idea when you'll be getting around to to doing a review of the Sennheiser HD 660S? I'd be interested to hear your thoughts on how it compares to the AFO.

JMAX2016's picture

If Tyll says it’s the best sub $1k open headphone, that means it beats the Elear. Right? If so, I have to hear these. I live in PA, any idea where I could hear them? And any idea where I could buy at a discount from MSRP?

seppukusword's picture

there is somewhat of a thriving market in sales and trade of pre-owned Mr Speakers headphones. Just Google around and you're bound to find them for about $400-$500.

I'd never sell my Aeon flow's. They are just that damned good and I've compared them to many, many options.

gixxerwimp's picture

You say in the video (9:00) that you saw the FR curve and thought the bump would adversely affect the sound. But in your "How Tyll Reviews Headphones" video, I recall you saying that you always listen for impressions before you measure so that you aren't influenced by them. Wonder if you can clarify.

Harry Manback's picture

It's interesting to see ads on head-fi for Mr. Speakers headphones with a quote from Tyll and a "wall of fame" badge.

I think that objectivity in reviews are now fair game to question. It saddens me that there are fewer and fewer truly objective reviewers around anymore.

So long I may visit you on occasion, but not regularly any more.

AncientWisdom's picture

It's a chicken egg thing. You're insinuating the ad is the chicken. But I (and I think most visitors here) believe the review is the chicken. If the review is objective and truthfull, what's wrong with Mr. Speakers using that in their advertisement? It's a truly thing in their favor. Something brands always struggle in in marketing is how to convince people that it's not just them themselves that think a product is great, so it makes sense to me to use such an endorsement.

seppukusword's picture

I get a kick out of some comments here where people make definitive statements about the Aeon Flow's vls the HD660's or the M1060's without every owning or hearing any of them. How does one become an expert on something without ever touching the unit?

Being in the position of owning the Aeon Flow's, the M1060, BD 1990 and the HD660s I can definitively say the Aeon Flow and the HD660 are so divergent from one another that comparing them is like comparing a tricycle to a Mclaren.

Spike_Goldman's picture

Whatever you do don't plug these Aeon Open headphones into any decent headphone amp and try to work. Right now I am supposed to be working and Van Morrison's Healing Game has me totally engaged and distracted.

Most money I've ever spent on cans. Worth it.