Axel Grell in collaboration with Drop is releasing a new open back headphone, with drivers placed in a radically forward position for an “ultra expansive soundstage”.
He designed numerous models for Sennheiser, including the HD 6xx series, HD 58x series, and the HD 800/800s. His bona fides are well established in headphone design.
This thread is for his new design, the OAE-1.
I think there’s some confusion about this headphone, partly due to the marketing and partly due to the placement of the driver at the front of the cup. From what I recall of Axel Grell’s presentation at CanJam SoCal 23, the placement of the driver at the front is not about simulating speakers in front of you. It’s about the optimal placement of the driver for the lowest acoustic impedance. Low acoustic impedance should give this headphone an open sound with a wide soundstage.
This blog post on Drop is a decent summary of this design approach:
An Englishman and a Usonian in green shirts with disturbingly similar hairstyles: Axel Grell’s Headphone! Hands on and impressions! (CanJam SoCal 2023)
The FR is a bit wonky, especially that cliff around 6khz. But the Signature Edition comes with an individual B&K 5128 FR measurement. So my plan is to start EQing pretty soon after arrival.
In theory the FR measurement should translate well to what we hear since the driver placement makes them less sensitive to individual HRTFs.
I’ll try it as is first, but that’s my plan as well. 
Mine should be arriving momentarily. Impressions soon.
But in the meantime, keeping up on the OAE1 topic on Head-fi be like
Mine comes on Tuesday supposedly. We’ll see, some headfiers first impressions are not so hot… It seems like fit and placement on your head are highly determinent of the sound quality.
Ok 2 hrs in mini-review:
I have both the HD6XX and HD800S. I am not a big fan of the HD6XX and I didn’t like the HD800S until I gave it a bass shelf and fed it from a tube amp. My desire from these was not a better HD650 or a speaker-like experience, but rather an HD800S with better bass.
I have a big head, but these fit me fine - at near max extension. Clamp is not bad but it seems to have a hot spot at the top of the ear cups no matter what I try. I may have to stretch them out.
Placement is not that sensitive for me but they definitely don’t sound as good if they are low. I think the imaging gets more distant if you move them forward too, but it’s not a big difference.
Sound:
Some of this could be just NRE, especially as my expectations were low. So obviously YMMV, yada yada. But I think as far as giving me an HD800S with bass - mission accomplished. It’s going to be fun comparing these to the HD800S, ZMF Atrium, and VZR Model One.
Now I’m gonna go back to listening to these things!
@AudioTool I was curious what chain or amps you are using with the Grells.
Opinions (like a**holes) on headfi are all over the place on what sort of amp or DAC works best with it, and at end of the day we each will use what we got! 
In my case it is Yggy OG with Nitsch Pietus Maximus or the Flux FA-10 Limited, as that’s what there is and those amps will do SE, since the amp I’d really want to try them with is XLR balanced only.
Anyway, when you have some more listening time on it it’ll be interesting to see if anything changes in your impressions.
Nice impressions. I’m curious, have you heard the Audio Technica R70x? I think that’s probably going to be the most apt competitor when it comes to soundstage and imaging.
I have a Schiit Bifrost 2/64 feeding all of my amps. Right now my favorite amp for these is the Schiit Folkvangr. Yep, they like tubes! But they sound really good off of my Schiit Mjolnir 3 too. I even fed them from my iPhone to try out some Dolby Atmos tracks. I still didn’t like the Atmos mixes but stereo mixes sounded pretty good.
i don’t know. For solid state amps, I tend to think if the amp is good, it is good for any headphone unless it is underpowered.
Sorry, I have not.
Some more thoughts on sound quality. These seem to really excel at live recordings and electronica. They struggle with metal. Aside: guess which genre I listen to the most 
. Listening through my music library I’d guesstimate maybe 10% of tracks sound bad, 20% ok, 50% hey that’s nice, and 20% OH MY GOD THAT IS NEXT LEVEL! Your ratios will be different depending on what genres you listen to.
So I think these have a place in any headphone collection but if you are looking for your one headphone, the best all-rounder for the price, the OAE1 ain’t it.
Of course this all assumes that the reason the impressions are mixed isn’t that the OAE1 are super sensitive to individual HRTF and I just happen to win that lottery.
I’m glad to hear you’re liking them overall, and in that 20% a whole lot!
How do they seem to struggle with metal? I guess I’ll find out, I’ll play some Tool through them! 
I’ve been listening to a lot of electronic music lately, and Norse/world/folk/Celtic stuff as well, like Eivor, Danheim, Munknorr, Trobar De Norte, etc. Often pretty simple arrangements instrumentally, with very dynamic deep bass drums in them. It’ll be interesting to see what the Grells do. I’ll try them with some jazz and rock as well.
I hope they work well with my head and ear anatomy too!
They sound dull, almost muddy and the soundstage collapses. These are not my favorite Tool tool - yet.
That said I’ve had some success with EQing the bass region so that it doesn’t bleed into the mids and that seems to really clean up the overall sound on busy tracks like metal. I’m wondering if there is some kind of comb filtering going on because they don’t sound too boomy out of the box(a little), but busy tracks get very blurry. Whereas tracks with lots of “space” between instruments are eerily realistic. If you close your eyes and try to imagine the performance in front of you, you’ll get like halfway between speakers and normal headphones.
Ok @robson is either too busy enjoying his OAE1 or doesn’t want to disagree with me. 
Either way I have some time to post a quick update. I have been listening to the OAE1 exclusively since receiving them and whether it’s my brain getting used to them or the pads compressing, they seem to have gotten better over that time. I’m not saying they are the best headphones I own, but I have no issues listening to all music genres including metal now. There are certain tracks where the upper bass is a bit much (EX: Tool - Pneuma), but all of my attempts to address this with EQ have resulted in thin mids in other tracks, whether tuning by ear or using measurements.
I want to do some A/B against my other headphones this weekend. It’s just been hard because I have been having a really good time with the OAE1. I did compare them briefly with my HD800S and the OAE1 are definitely better at getting the soundstage out of the middle my head. I still don’t think they sound like speakers in front of me though.
I’ve also been trying the crossfeed built in to Roon with them. It doesn’t make them sound more like speakers in front of me. The center isn’t any further forward, but it brings the extreme sides around from either shoulder to more front angled. I definitely like it for live recordings. Studio recordings I turn it off for pop or electronic where I prefer the surround sound effect. For rock and metal, I prefer it on to keep the hard panned electric guitar from playing right in my ear. I’ve tried crossfeed many times before but I’ve never liked it enough to leave it on for more than a few minutes. I could leave crossfeed on with the OAE1 and be perfectly happy.
Still gathering my thoughts, I’ll post shortly! (it didn’t come until Wed…)
I haven’t posted any impressions until now because I feel fundamentally conflicted with the Grell…
It’s both disappointing and intriguing at the same time. I’m disappointed with its ergonomics, and with its fundamental inability to do a good job resolving detail much of the time. It’s just OK in resolution. It’s also weirdly dark and bright at the same time, and while there is pretty deep bass, it’s kind of flabby and definitely lacks in definition. But occasionally it sounds simply fantastic (maybe 15% of the time), and its headstage is very interesting.
Recording quality and genre also make a difference… I tried some Bach piano sonatas with Glenn Gould, and I didn’t think the piano sounded right. It has sounded good with electronic music and some current Reggae, but not so good with some older rock recordings. I feel like the Grells sound pretty great 15-20% of the time, just OK maybe 50%, and not good or worse about 30% of the time, IDK… YMMV and all that.
It needs a good deal of power, and positioning on the head is crucial. I’ve yet to dive into EQ’ing with it, so I’ve been using it as is. It was also an oddly disorienting listen at first, I felt like it sounded out of phase or had too much cross-feed applied. I checked both, and used my trusty Stereophile test CD rip to make sure all was set correctly, and it was. It takes some “brain burn it” to adjust to it I think.
From what I’ve read trying to use this with a dac/dongle will result in disappointment, and even a 1W amp is most likely not enough. I’ve used it with mostly the Flux FA-10 Limited, and to a lesser extent the Nitsch Pietus Maximus, and while it sounds good on both I think the Flux is a better pairing as it more resolving, and has a bit more treble forward tuning.
The Pietus Maximus is also a very good match though, and it does help bring up the mids on the Grell. It has a very pleasing tonal balance overall.
I also had connector issues at first in spite of all the warnings about it! Inserting the cable into the cup requires and audible click for it to insert properly. Push to click really applies here!
I only briefly tried the Grell on my DSHA-3, as I just got a 4.4 to 4 pin XLR adapter. While the OAE1 sounds marginally best on this amp, I don’t feel the headphone “scales” enough to really make a lot of difference what amp (or DAC) you use beyond a certain point. I generally prefer a multibit/R2R type of DAC, and something like a Modi Multibit or Bifrost 2 paired with an equivalent amp should sound fine with it, among many others.
TLDR;
The Grell OAE-1 is a worthy effort, and I appreciate the thought and design put into it. I think it looks good, and is of pretty high quality for its price. I definitely would want to see more extension for the arms, and less clamp pressure. The overall look and package is very nice, though the SE cable is a disappointment. From the product description it sounds like both cables are comparable in materials and construction, but they are not. The balanced cable is clearly of higher quality.
Would I recommend the Grell OAE-1? Probably not, as it currently is. If someone is looking at this vs a Sennheiser 600/650/6xx, I think those are a better choice. What they do well, they do much better than the Grell. Yes, the Grell has better bass, and a much bigger/wider soundstage, but tonally it sounds off. The HD 600 series have a much more realistic presentation of what the music sounds like than the Grell.
I will also mention the DCA/Drop Aeon RT/X line as possible alternatives, which when on sale would be close(ish) in price to the Grell. Again, they are more resolving, and have a more musically realistic sound (to me anyway) than the Grell.
I will probably keep mine anyway, as it is an interesting design. The only other “ear speakers” I know of are the Raal and the MySphere, but I’ve not heard either. But I’m still undecided…
What I’d like to see in an OAE-2: bigger cups, more extension and less clamp pressure, a more resolving driver, and a smoother, less wonky tuning. I kind of view the current OAE-1 as a late beta, or a late release-candidate if it were software. Almost there, but not quite!
I’m glad you’re enjoying yours though @AudioTool!
I am enjoying them quite a bit, but I also agree with everything you’ve said. That is the fundamental problem with the OAE1. They are the most “Mary’s Room” headphone I have ever owned.
Some (not all!) of OAE1 problems are because people are expecting it to sound like a headphone, but with the music coming from in front of them. I don’t think that is a realistic expectation. I’ve used several speaker simulators and they all change the tonality. Also, and someone with more experience will and should correct me, I think a good pair of headphones will always sound more detailed than speakers.
I would recommend this headphone to anyone who has a collection and is curious. More so if you’ve owned or own an ear speaker like MySphere or Raal SR1x. You’ll need to either be open minded to the tuning or be willing to EQ by ear. I would not recommend this to anyone who is looking for the overall best headphone in this price range. It’s just too different.
The effect of these sounding better the more I use them does seem to be from brain burn-in. Switching back to conventional headphones for a time and then returning to the OAE1, they sound a bit dull and muddy. However I have had some success with EQ. @listen_r created a Headphones.com EQ preset but it doesn’t sound right. I’m going to continue to play with it but I’m not convinced this or other Harman-like targets are appropriate for these, although I can’t objectively explain why.
So instead I developed my own preset with the hope of mitigating the biggest issues with the OAE1 FR. It’s early days but this is what I have so far:
Preamp: -3.36 dB
Filter 1: ON PK Fc 180 Hz Gain -2 dB Q 0.8
Filter 2: ON PK Fc 3800 Hz Gain -4 dB Q 2
Filter 3: ON PK Fc 5900 Hz Gain 4 dB Q 3.2
If anyone tries this, I’d appreciate any feedback.
