Review written by Andrew Park (@Resolve)
Headphones provided for review by a community member
The first time I spent time with the Abyss Diana Phi, I wasn’t thrilled with it. I found it did some things well, but I couldn’t get over the comfort issues where the pads would dig into the sides of my temples. As it turns out, there have since been some revisions to the Diana Phi, including a revision that changes the pads to the ones found on their lower end ‘V2’ model. I got to try these out at CanJam NYC this year in February, and while they did improve the comfort quite a bit, the real star of the show for me was what YouTuber DMS had done to modify the pads on his Diana Phi. I have to say it left a strong impression on me, both because of how much more comfortable it was to wear, but also because DMS happens to be one of the coolest guys to talk to about all things headphones in general. You can check out his YouTube channel here.
Ever since then I’ve been itching to take another crack at the Diana Phi with his pad mod - effectively allowing me to actually enjoy the comfort benefits imparted by a lightweight compact planar magnetic headphone that’s meant to compete with other flagship top-tier crazy high level detail headphones. In many ways, this was the answer to my long search for flagship level performance without the flagship level weight and comfort issues.
Thankfully a community member who bought one (and got the DMS pad mod for it) was kind enough to send it in for review.
It should be noted that the following is a review of the Abyss Diana Phi with the DMS pad mod, not with the V2 pads nor the original pads.
- Headphone type - over-ear open back
- Driver - 63 mm patented Phi planar drivers
- Case - Dual zipper canvas carry case
- Weight - 350 grams
- Impedance - 32 ohms
- Sensitivity - 91 dB/mw
- Cable - Includes cable by JPS Labs, length 1.5 meter/5 FT, with choice of 3.5 mm, 2.5 mm balanced, 4 pin XLR or 4.4mm balanced plug
- Price - $3,995.00
- iFi Pro iDSD -> Cayin IHA-6
- iFi Pro iDSD -> SPL Phonitor X
- Mytek Liberty DAC
- Auris Audio Euterpe
- Earmen TR-Amp
- iFi iDSD Micro Black Label
Build, Design & Comfort
Abyss has made a big deal about their headphones’ reliability, demonstrating this by running over their flagship AB-1266 Phi TC with a jeep. While I don’t recommend doing this to your headphones, it was impressive to see that it still worked afterwards. The Diana Phi seems to also have a solid build, and I get the feeling that it will last a long time. This is helped by the lack of any hinges or articulating pieces - the cup and arm are all one piece, with the only moving action being from a magnetic extension system to the arms.
The first Diana Phi that I evaluated unfortunately had the older style of pads, and while it was impressively lightweight, I found the headphone to be particularly uncomfortable. This was because the angle of the cups wasn’t strong enough for where the pads would rest against the side of my head, meaning the pads would sharply dig into my temples. Abyss has since moved on from those pads and gone with the softer and more plush ‘V2’ pads, but even those ones aren’t as comfortable as the pads DMS has modified. Essentially he’s taken some of the material out of the top and side of the pad to help both fit and comfort. This means that with the DMS pad mod, the Diana Phi is one of the most comfortable headphones I’ve ever used - it fits me perfectly and for long hours of use.
The Diana Phi is a single-sided lightweight planar magnetic headphone, meaning rather than using a traditional dynamic driver with a moving coil behind a cone or dome diaphragm, it uses a flat surface with a conductive trace affixed to it that’s immersed in a magnetic field. You can read up about the differences between planar magnetic and dynamic driver headphones here. What’s impressive about the Diana Phi, however, is that Abyss have managed to make this an extremely lightweight design at only 350g. Not only that, but it’s rare to see a planar magnetic headphone at this price (with this level of performance) that uses a single-sided magnetic array. We usually see double-sided arrays like the ones found in the Audeze LCD-4 at this level of performance, and so it’s been interesting to see that it’s indeed possible at lower weight classes as well.
When evaluating detail retrieval and image clarity across the full spectrum of headphones available on the market, we can group them together into a number of different categories or tiers. There’s low to mid level, mid to high level, high level, and then the ultra high top tier crazy level of detail that contains headphones like the HiFiMAN Susvara and HE1000se, Audeze LCD-4, and Final Audio D8000 Pro. I find that the Diana Phi fits into this top tier category for detail retrieval, however I’d place it closer to the bottom of this category than the top of the category.
For midrange detail, the Diana Phi is right up there with the best of them, and it’s truly remarkable that Abyss has been able to put this level of detail into such a small package as the Diana Phi. Bass and treble detail is also good, but I find it to be just one small step behind the other flagships mentioned above. This may partially have to do with the tuning, but I wasn’t as immediately ‘wowed’ by bass and treble detail on the Diana Phi as I was with its midrange.
But let me put this in as clear terms as possible, if you’ve never heard one of these top tier headphones, with the Diana Phi, you absolutely hear details in your music more clearly than you thought possible. It’s one of those headphones that gives you detail that you didn’t know existed in the music.
Speed & Dynamics
The Diana Phi is also one of the fastest sounding headphones for the immediacy of the initial leading edge of each tone that I’ve ever heard. It’s once again right up there with other flagship planars, and for speed I think it may even be closer to the top of that category. This means that everything sounds tight, well-controlled and well-defined.
For dynamics the Diana Phi is also decent. For a single-sided planar magnetic headphone, it’s actually better than decent. It doesn’t slam as hard as some of the Focal or ZMF dynamic driver headphones, and similarly it doesn’t have quite the dynamic range of softs to louds throughout the rest of the frequency response, but for a planar magnetic headphone it’s still on the punchier side of things. I find it’s still slightly behind that of the Audeze LCD-4 and the HiFiMAN Susvara, but ahead of all the egg-shaped HiFiMAN headphones like the HE-1000se.
Soundstage & Imaging
Soundstage and imaging is where the Diana Phi shows some limitations - at least to my ear. It has decent lateral definition, and pretty good forward presence as well for the center image, however front left and front right aren’t as evenly distributed or have as much depth presence as I would have liked. I also find that when you hear an instrument or sound pan from left to right or right to left, the crossover in the middle is much more immediate, once again showing some limitation when it comes to image placement and even distribution across the front.
Still though, it’s not tight or in-your-head sounding, and it’s spacious enough to not get in the way. I think for most audiophiles this won’t be a problem, even if it may not satisfy gamers as much - although I’m not sure how many prospective customers would be getting a $4000 headphone for gaming. Maybe there are some out there with deep pockets.
It’s important to separate timbre into both a material and transducer related analysis and a frequency response related analysis. The former considers timbre as an analogy to instruments having a different tone to them even at the same pitch, and the latter considers timbre as the way the headphone impacts the timbre of instruments being played in recordings being listened to. In many ways, the latter consideration can also be thought of as tonality and tonal balance, just in how it affects instruments specifically.
To be clear, it may be the case that material and transducer related timbre is captured by frequency response, and there may be some correlation to be drawn for certain characteristics of planar magnetic headphones in comparison to dynamic driver headphones. But as of yet I’m unaware of any particular area of the frequency response or behavior that we can point to and call ‘timbre’.
The Diana Phi doesn’t have any major problems when it comes to material and transducer related timbre, meaning it doesn’t have a sense of dryness or unnaturalness imparted by the planar driver. It’s frequency response related timbre on the other hand is particularly unpleasant and unnatural. In particular it has a kind of steely and shimmery sound for most recordings, especially for instruments that token upper frequencies like cymbals. It turns out there’s a reason for this, as we’ll find out when we look at the frequency response below.
Frequency Response & Tonality
The following is how the Abyss Diana Phi (DMS Mod) measures on the GRAS 43AG standardized measurement rig relative to the combined Harman target curve (Harman 2013 bass but Harman 2018 mids and treble). For reference, the Harman 2018 bass is substantially elevated - far too much for what I think most audiophiles would consider appropriate, even if some bass heads may like it, so I prefer to use the more modest 2013 bass shelf. In any case, these are raw measurements, meaning it should not look like a flat line across. This instead shows the raw measurement relative to the target that would otherwise be normalized in compensated measurements.
How do you read this? The dotted black line is the target (how we might want it to measure), and the blue line is how the headphone in question measures. Effectively, this shows how significantly the headphone’s frequency response deviates from the target.
It has to be said that the Diana Phi both sounds and measures quite differently depending on how it's positioned on the head. The following graph is how I found it to measure most consistently with the middle position, which was also the one I tended to prefer.
Diana Phi with DMS Pad Mod - Middle Position
At first glance the frequency response looks pretty good. It elevates at the appropriate range between 1khz and 8-9khz, meaning that it follows the ear-related gain factors our brains expect to hear for the most part. But with that said, there are some oddities worth diving into.
The bass is well extended, and even follows the 2013 Harman shelf to some degree, which is rare for open-back headphones. It should be noted that when you pull the Diana Phi away from your ears slightly, the bass seems to go up (similar to what happens with HiFiMAN headphones, and it’s not uncommon to see this with planar magnetic headphones), and that’s why we see the high variation for bass measurements depending on positioning. For the most part, I think the averaged line is the typical bass response though, but for anyone wearing glasses, or if you have a smaller head, you may find there’s more bass presence.
Thankfully the bass stays well-controlled and doesn’t bleed into the mids at all, which are also excellent up until about 1-2khz where there’s a bit of forwardness. It’s not enough to be a significant issue, but it does impart a slightly thicker and more congested kind of sound to the mids. Then things start getting a bit odd in the upper mids. There’s a noticeable peak around 3khz depending on the headphone’s positioning (backward or forward will shift where this peak is). The 3khz bump is mainly an issue because of the gaps on either side of it, meaning that overall it has a slightly disjointed or convoluted sound to the upper mids. Once again this isn’t a huge problem, but it has the effect of not sounding as ‘filled-in’ for orchestral swells often found in classical music.
Then we get to the treble, which is where the only substantial issues lie - at least to my ear. While there’s no emphasis to sibilant tones throughout the consonant region, making it smooth and agreeable for the mid treble, the Diana Phi unfortunately has a substantial peak around 10khz.
Now it doesn’t look all that bad, and indeed it almost looks like it gets closer to the target and that this should be a good thing. But this is actually where there should be a dip from interactions with a certain part of the ear (concha). The fault for how this looks is with the target, and it should probably be dipped there as well. While this kind of target is useful for getting a sense of general tonal balance (Harman 2018 in this case), it’s not so good for diving into the intricacies of how our physical ears impact sound before it hits the eardrum. Basically, we have to remember that the Harman target is an averaged consumer preference curve, and it doesn’t take into account what our ear shapes are doing to the sound - meaning it doesn’t appropriately reflect how headphone measurements should look with a more fine-grained analysis.
Instead of the elevation at 10khz that we see on the Diana Phi, we should see a dip anywhere between 9-10khz. Because, without this dip, there’s a very strong resonance that comes across and imparts the kind of unnatural ‘shimmering’ effect that permeates large portions of the mix. It’s mostly noticeable with cymbals, but I even hear it coming through in the background for certain vocals. I think this may have been one of the areas that was difficult to identify during show conditions at CanJam in NYC when I first heard it - or it may have been from a particularly warm source.
In any case, the rest of the treble sounds pretty good with a decent amount of presence at 12-14khz, but then above that there’s another striking resonance that shows up. I think this last one won’t be as bothersome for most people - or at least how bothersome it is will likely depend on the age of the listener. As we get older, our hearing tends to roll off at around those frequencies, and while we may still be able to hear 16-18khz when paying close attention, the overall volume of those frequencies is usually a lot less. Still, I do find it to come across occasionally for certain cymbal hits, and this causes the upper edge of the sizzle quality to overshadow the fundamental tone of the cymbal hit, emphasizing the somewhat unnatural sound.
Overall, however, apart from one significant issue in the treble, I find the Diana Phi’s frequency response to be quite pleasant. It has a somewhat warm kind of sound to it with a bit of that forward mid presence over the lower treble with good bass extension. It’s really just the somewhat steely and unnatural shimmering quality around 10khz that needs adjustment, but once that's done this is a wonderful sounding headphone.
For anyone not willing to EQ, I recommend using the Diana Phi from a warmer source to help curb that treble shimmer, however for anyone looking to get into EQ, I highly recommend doing it with this headphone. The main (and potentially only) area to adjust is to add a 10khz peak filter with a Q value of around 5 or higher, and reduce it by about 6.5 dB. Keep in mind, this should be done by ear, and not by the frequency response you see because it will change depending on how it’s positioned on the head.
With that said, here is my EQ profile that also evens out the mids a bit:
Compared to the Focal Utopia, I find the Diana Phi has slightly better detail retrieval with a bit better lateral definition and forward presence, but the Utopia has a more agreeable frequency response and tonal balance and has slightly better dynamics. The Diana Phi is also quite a bit lighter and more comfortable for long listening sessions when using the DMS pad mod.
In my mind the Diana Phi after EQ is a direct competitor to the HiFiMAN Susvara. This is because these are the only two headphones in this top tier flagship crazy detail category of headphones (apart from maybe the HE1000se) that are actually comfortable to wear for longer periods of time. I find the Susvara has better tonal balance, better soundstage, and better detail for bass and treble, while the Abyss Diana Phi has very similar midrange detail, is lighter (more comfortable with DMS pads), and will likely last longer - although I haven’t seen any failure rates for either. In my mind the Susvara is worth the extra $2000 if you’re not comfortable doing EQ, but if you are okay with it or finding some way of adjusting 10khz on the Diana Phi, then it becomes a solid competitor.
I find the LCD-4 to have better bass detail and slam, but the mids are about on par with the Diana Phi. The LCD-4 may be better extended in the bass, but it also sits a bit lower than the Harman shelf, whereas with the Diana Phi I found that some positions actually elevated the bass quite a bit. The LCD-4 has really good treble detail as well, and I think somewhat cleaner sounding than the Diana Phi, but the LCD-4’s tonal balance issues aren’t as granular as they are on the Diana Phi as well, so maybe that’s where some of the difference comes from. As much as the LCD-4 is a very impressive headphone, the weight of it is a bit too much for me to handle, and so I would happily take the Diana Phi over the LCD-4, since both do need some EQ in my opinion.
The Abyss Diana Phi with DMS pad mod is a headphone like no other. Yes it has some tonal balance issues and that unnatural ‘shimmering’ issue that needs some EQ, but if you’re comfortable doing EQ, or maybe you have a warmer source to use it with that curbs some of the treble resonances, the Diana Phi gets my recommendation. This is the first truly lightweight and compact planar magnetic headphone that achieves top tier level technicalities and it should be celebrated for that reason alone. This has been one of the most fun headphones I’ve ever had the pleasure of spending time with, and if anyone is considering getting a Diana Phi, I highly recommend asking for the DMS pad mod as well.
-Andrew Park (@Resolve)
Watch the video review here: