Abyss AB-1266 Phi TC

susvara,sr1a,lcd-4…including the TC best I have heard

Yes that is the order

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… looked interesting. Much like the 1266, but easier to fit. BUT … more expensive!

It’s more expensive because marketing and the whole selling to dealers only.

Great review from @directorsgarage. I previously didn’t really appreciate its adjustability for fit and sonics. I need to pull that Simon and Garfunkel album.


Okay guys, I’ve spent some time with the AB1266 Phi TC and am ready to post my thoughts/conclusions. There will also be a video review coming out soon that I’ve been working on. For anyone wondering, this is a recent unit from sometime this year, and it was sent in by Humble for review - big thanks to Humble for sending it in!

Video review:

Non-audio stuff:
Heavy… good lord. I don’t think I’d be able to wear this as long as I typically like to listen. BUT, the suspension strap helps with top of the head fatigue that would otherwise occur. So, despite the weight, this is not as uncomfortable for me as I was expecting. I think others may find it more troublesome, since it’s also a super unique fit/wearing situation. You almost have to walk into them like you’re about to get an X-ray at the dentist (I just had that done and I was like “this is exactly what it feels like”).

Also, this thing is built like an absolute tank. I mean, they ran one over with a jeep.

Default Frequency Response (middle position with a seal, how I ended up wearing it most of the time):

This is a weird one. Definitely not a particularly neutral or even frequency response, but it’s also a bit interesting. Mainly there are two things to note - there’s a particularly forward area around 1.2khz that causes quite a bit of honk/glare to certain instruments. The second thing is that there’s a resonance around 5khz that stands out. Normally this is something I’m particularly bothered by, but in this case the upper treble emphasis serves to balance out those harmonics reasonably well. This means it doesn’t have the typical ‘percussion compression’ issue as I like to call it when you see a 5khz peak that dominates the FR causing a harmonic imbalance. So… the upper treble air is maybe a bit boosted there, but… it sounds smoother than it looks.

On the flip side, the midrange glare causes the whole thing to sound a bit weird - almost ‘boxy’ and metallic at times.

For owners of this headphone, I have a suggestion worth trying - and I’m curious to hear feedback on this - try reducing 1khz (or around there) by like 3dB with a fairly wide Q value if you can and see how that sounds. You could also drop 5khz but I hesitate to suggest too much EQ on this headphone, partially because you’d need to use some narrow pk filters that might be tricky to get right.

Channel Matching (for Crin!):

I’m mainly just posting this because there seemed to be some question marks regarding channel matching on this headphone in certain places. It’s generally not a problem on this unit at least - but it may be difficult to achieve it in measurements due to the semi-sealed positioning variation on this headphone. But… I tried at least.

FR Backward Angle (this was uncomfortable for me, so I didn’t typically use it like this):

In addition to seal vs no seal - and forward/backward differences, I noticed some change to the FR when the headphone is worn at a slightly different angle. The top headband piece can be angled inward, remain straight across the top, or angled backward. I typically found it to be best when it remained straight but I did find some slight differences when angling it, but generally I had a hard time with comfort at those positions.

FR Air Gap (shows driver resonance frequency plus damping Q factor):

So this is interesting, perhaps more so on this headphone than others, and that’s largely because it’s not obvious that it’s supposed to be worn with a perfect seal. This means that in certain situations you could get a much stronger bass response. Not only does it have a reasonably low driver resonance frequency, the Q value is extremely high (narrow). I’m actually shocked at how massive the driver resonance is for this headphone, I don’t think I’ve ever seen anything behave like this.

On-head Response (do not compare this with GRAS or other industry standard rigs, this is just for bass and coupling evaluation):

The on-head response here shows that I was getting some minor leak, as you can see by the slightly elevated bass response there. I was curious to see how well it was sealing on my head, and the top piece can be adjusted so that you intentionally get a leak, but in my case I just preferred it as is and this was the result. Kind of a clever way to get a bass boost in an open planar.

Distortion Channel L:

Distortion Channel R:

So this distortion is… uncharacteristically high. Also what’s weird is that there seemed to be considerably more stuff going on with one channel than the other, but looks to be in the same places. It’s important to note as well that unlikely to show an exactly repeatable distortion measurement that looks the same every time.

In any case, the question here would be… is this audible? My answer is… yeah, with test tones at certain volumes. Is it audible with music playing in normal situations? At the very least this is far less likely. The major downside to me is that I’d worry about applying too much EQ to this headphone, and that’s something that I find it could use.

Subjective Findings:
For anyone wondering, I’ve run this off of all kinds of sources, including the Topping A90, the Burson Conductor, the Violectric HPA V550 (balanced out), the Bakoon Amp-13R, and on the lower end I did try it with the Heresy as well. This should be obvious but… you really need an amplifier with this headphone.

  • Detail - Outstanding. This is up there with the very best when it comes to certain things like the immediacy of the initial leading edge, and clarity for trailing ends of tones. Separation and incisiveness is also top tier.
  • Soundstage - Mostly normal, not super wide but not tight either. I can also hear all the instruments in very distinct places within the mix, so I’d say it’s solid for depth and layering.
  • Macro Contrast (Macrodynamics) - Remarkably punchy. This rivals the HE-6 for physicality, tactility and liveliness. There are so far only three planars that I’ve heard that do this exceptionally well, and the Abyss is one of them.

My experience with the Abyss AB1266 Phi TC has been an odd one. I keep thinking that if Abyss could get their headphones tuned a bit more in line with common preferences - especially in the mids and upper mids, they’d have some real winners on their hands. In addition, that distortion behavior… while it’s not an indicator of sound quality the way FR is, I lean towards thinking this should probably be a bit more under control at this price - especially when you consider how that might impact EQ potential.

But with that said, the experience here for all of its non-tuning related qualities is near top tier in every category I value. So, I’ve been struggling how to think about this - because I definitely still prefer the HiFiMAN Susvara - but the AB1266 Phi TC is like… a weirdo Susvara but with better slam. It’s definitely too ‘colored’ for my taste, but I also do see why people like it.


The 1khz peak goes back to even the original AB1266. I’ve tried various EQ settings with the original, the Phi, and TC, lowering that 1khz peak, at various Q settings, and for some reason, it always ends up not sounding as good to me over the long run. Initially I might find it “interesting” sounding, but I always end up going back to the stock tuning, for whatever reason.

Yet, when, out of curiosity, I try boosting that area with other headphones, it never sounds right to me either, always sounding kinda…weird.

I think, for whatever reason, the 1266’s tuning just “works” for me and my ears, but there are absolutely people it doesn’t do it for. Which of course, is why there are all sorts of headphones and tunings out there :slight_smile:

“a weirdo Susvara but with better slam.”

thats a very good way of putting it IMO :slight_smile:


this is gonna be a nice spicy review with those distortion measurements when that vid drops haha. What was your favorite Amp you tried with the abyss?

So the distortion measurements are once again pretty shocking because this absolutely sounds like one of the cleanest, most transparent headphones I’ve ever had. I currently also own the Susvara and I expect it to measure better with distortion. The Susvara sounds warmer, more relaxed, and I guess that could be because of the lower distortion (again assuming here as I don’t have the measurements on hand).

Whatever the measurements may indicate, subjectively (controversial word, I know, hehe) the Abyss TC are one of the most exciting, tactile, satisfying headphones I’ve ever owned. They absolutely envelop me with sound and demand my attention and involvement in the music like no other I’ve tried.

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Well I write this while my Susvara sits next to my AB 1266 and I can say I don’t get these measurements at all. While I prefer the Susvara the 1266 sounds outstanding. I wonder if you can get good measurements off this weirdly styled rig which I still don’t like wearing. Its all too much. I am going to put on my ZMF Verite C and think about it a while.

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Actually the measurements were quite consistent with that position. It only changed meaningfully when I deliberately changed the angle or the forward-backward tow. But yeah if that’s what you mean the results will be a bit all over the place. Did you get a chance to try -3dB at 1.2khz? I’m curious how that sounds for folks with this headphone.

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Don’t get me wrong–I treat you like those mentally challenged guys do Zeos. You say it I buy it. Got $100k bill to show for it. But if you watch the Abyss how to use our grossly expensive stuff videos they talk about angling the pads and moving back moving forward. I still dont get it right so maybe I am just too deaf or dumb. I am going to do the EQ tomorrow. Up to this point I have not even bothered after 6 months. Will report back over weekend.

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Is the Abyss worth the price tag?

Thanks for the review, it matches my impressions of the 1266 for the most part. I’ve owned them for about 4 months now and use them with the Formula S and Powerman and the Pontus II dac. What dac were you pairing with the amplifiers you tried? Compared to headphones that I’ve used I would describe the 1266 TC as a cross between an HD800S, an LCD-4z (haven’t heard the 4), and a subwoofer.

I will do some listening tonight and will have to try out that EQ setting of decreasing 1k by a few db. I’m generally not a fan of EQ but I am interested in what this does to the sound of the 1266.

For me the 1266 TC is the best headphone I’ve heard and make my HD800S and LCD-4z mostly irrelevant but I still listen to them from time to time as the 800S are a bit more comfy and do well with jazz while the 4z has somewhat more forward vocals that can be nice although the texture on vocals doesn’t quite match that of the 1266. I’d like to hear the Susvara at some point but for now I am very happy with the 1266 as my main headphone.


It is a close call. It is in my opinion overpriced but not so much as to make me regret buying it. If I had to choose though I would take Susvara which cost me $4400 straight from factory. I can make an argument for the price but it is a heavy indulgence. Definitely great headphones though.

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I also own both, and I prefer the Susvara for about 70% of what I listen to over the 1266.
The measurements don’t really reflect what I hear.
A friends gf who wasn’t an audiophile and preferred the Susvara (to my surprise) had the most insightful comment on the 1266 I’ve heard she called the sound more chrystaline which resonated with what I hear.

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I’ve been using these PEQ settings in Roon and notice a more comfortable sound, if anyone wants to try them. They’re a slight modification of the PEQ posted on ASR

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Interested in whether the 1266 or Susvara would better compliment ZMF VO? I’m looking to purchase one, however unable to audition due to COVID, often don’t listen to all that well recoded music… appreciate any thoughts!

I tried the -3 db at 1k with a Q of .7. It sounds like it softened the attack of some instruments and vocals in that range. I like an exciting sound so I’m not sure I like this adjustment much but for those that may prefer a smoother frequency response I think this is definitely a step in the right direction

Thank you. Going to give that one a try for sure. Appreciate it.