RAAL-requisite SR1a - Earfield™ Monitor/Headphone - Official Thread

One of the most interesting, and unique, recent entrants into the Headphone (RAAL-requisite call them "Earfield™ Monitors) world is the SR1a. They’re the first headphone using a true ribbon-driver (known for being extremely resolving and very fast), which was developed by RAAL, in Serbia - who are probably the most well known, and well regarded, manufacturer of ribbon-drivers for speakers:

To quote RAAL-requisite on the SR1a:

The SR1a by RAAL-requisite is the world’s first Earfield™ Monitor. Experience mixing, mastering, and home listening with unparalleled accuracy and realism in a soundfield devoid of room acoustics and comb-filtering caused by work surface reflections. Earfield™ technology delivers unheard of program accuracy and a speaker-like soundfield experience.

Why is this good, and how/why does it work?

You’ll have to excuse my coarse interpretation of things … you can read up in more detail on their website.

By not using a traditional cup (or baffle), and with the full-range ribbon drivers being held away from the ears, they’re able to bypass a lot of the tuning challenges imposed by both the cup, and the more typical headphone-to-ear driver relationship. At the same time, they’er subjected to the full effects of the external and internal ear structures (which shape frequency and time-domain uniquely - as all our ears are different). The simpler version of which is that they can be tuned to be neutral, and will then be perceived by the listener with the same principal response as a flat-tuned speaker.

There are differences in how the Head-Related Transfer Function works here, as the sound is coming from in front of the ear, not in front of the head, but there is still a natural level of crosstalk between left and right channels, and the result is not only a more natural frequency response, devoid of room interactions, cup interactions and ear-to-driver positioning issues, but also with a much more natural, and dimensional, stage rendering (more depth).

Another unique aspect of these headphones is that they require a proper speaker-amplifier to operate (100w into 8Ω or 150w into 4Ω is the minimum quoted requirement).

The booth for these at CanJam @ RMAF 2018 was perpetually busy. All the listening stations were in use every time I stopped by … so it was pretty clear that interest was very high!

And … this is the spot to discuss them …


Very cool look!

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I started this thread now as I have a pair of SR1a inbound and, with a little luck, arriving before the weekend. I am, of course, planning on a full review* of these once I’ve gotten some proper time with them.

Excepting the driver technology, which is completely different, the closest headphones to these in terms of being suspended forward-of-and-away-from the ears would be the AKG K1000** and their “spiritual” (or perhaps “inspired by”) successors the MySphere 3.X (which I also have in-bound for proper review). Those both have much more vivid imaging and substantially more depth to their stage than any other dynamic headphones I’ve heard … can’t wait to see how the SR1a do in that regard!

Since the SR1a actually require a speaker amp to drive them, and a non-trivial one - power-wise - at that, I will be reviewing them with several current-production speaker amplifiers, ranging from $500 to >$5,000 and comparing the results.

*The ZMF Vérité, and long-overdue Schiit Multi-Bit DAC Comparison/Review, will come first as I’ll need time with the SR1a to evaluate them properly.
**If you ever get to visit Bottlehead (of “Crack” fame), you’ll see Dan has a bunch of AKG 1000 in the shop/demo area. Never seen so many in one place.


Wow, they look like no other headphone I have ever seen. I kinda like the look.

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I am really looking forward to your thoughts on this one.

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once seen can’t be unseen moment I’ve had looking at these… I will not ruin it for the rest of you. I look forward to hearing your impressions also @Torq and maybe sneaking in a listen for myself =)


So, will the cable that comes with these headphones have banana plugs or some other such type of speaker cable termination on one end?

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They actually have a special adapter box that you connect to your speaker amplifier using normal speaker cables. This provides a ~6 ohm load to the speaker amplifier vs. the 0.2 ohm load of the actual ribbon drivers (if you drove the ribbons directly from the amplifier it’d immediately go in to over-current protection).

The adapter box then connects to the headphones with a reverse-gender 4-pin XLR so you don’t accidentally plug a normal headphone into it.


Ah, well that makes more sense and is a lot more convenient. But if you don’t have a dedicated speaker amp for the headphones you would need one with two sets of speaker terminals or you will constantly have to muck about at the back of the amp switching cables around.

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You could also add a speaker switch between the power amp and the speakers/adapter box.

It would not surprise me if, in the future, a more flexible adapter box became available that allowed switchable pass-through operation for the same reasons. Maybe some level of treble-biasing as well (there some posts showing mods that affect the treble emphasis as it stands).

I’ll be using a dedicated power amplifier - though which one specifically will depend on both how different models performs and how much of a wait is involved in getting what I want.

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Yes, a more flexible adapter box that allows switchable pass-through would be a very good idea. Treble biasing on the adapter box or why not just EQ the way you would any other system?

I look forward to reading your review.

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Not everyone can (or wants) to run EQ in their setup.

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I’ve been listening to the SR1a for a couple weeks now, and it’s impressive.

My chain is Roon -> Yggdrasil A2/Convert-2 -> Phonitor X (balanced preamp) -> Aegir x2.

The SR1a is certainly the widest, most focused, and realistic soundstage I’ve heard on headphones. Very detailed and distinct layering of sound. Astonishing resolution and detail. Clear, strong and bright treble; rich, sweet and full mids. Lower registers are clear and natural, and even full - but distinctly different from the Vérité, LCD-4 or the Abyss. Truly delightful.

Overall, a transparent sound - very comparable to live music (I listen mostly to jazz).

A bit awkward wearing them - but they’re comparatively light and comfortable once you get them situated. They had a weird burnt odor at first - I’m guessing that’s from the foam they were packed in. The design is utterly functional without much regard to aesthetics. They’re advertised as “ear-field monitors” and that sounds about right.

Twin Aegirs in mono seem plenty, though I have no way to compare. The Convert-2 has interesting synergies with the SR1a.

My preferred chain is still Yggdrasil A2 -> EC Aficionado (300B) -> ZMF Vérité. But this could be right there beside it.


I’m guessing it’s from your sizzling hair due to 100 watts shorting out next to your head! :stuck_out_tongue:


As a huge fan of ribbon speakers - I had Apogees until my wife decided they were too big - I’m really interested in these. The sound of a good ribbon speaker is hard to beat, assuming you’re sitting in exactly the right spot, and have the appropriate amplifier power available. Can’t wait to hear what you think, @Torq


That was one amplifier configuration I was going to test, and include in my comparison, as part of a full review - but also something I planned to put in an early “stream of consciousness” commentary ahead of that.

Unfortunately I waited until I had confirmation of my SR1a shipping before placing the Aegir order, and now they’re back-ordered until 7/2! So, it’ll still happen … just it’ll probably have to wait for the full review.

Comparisons will also include Vidar (stereo for sure, maybe dual mono also …) - which will get early coverage/comparison. The SPL Performer s800 (these are rare as hens teeth in black right now, with no clear indication when I can get my hands on one). Maybe the Benchmark AHB2, since that’s what they were developed against (they’re backorder for the next two weeks). A Linn Akurate 4200. And then a smattering of other amps ranging from ~$500 on up.


looking forward to your impressions, @torq


I’m interested in this. I’d be particularly interested in hearing how they sound with different kinds of decent amplifiers. Despite their nominal requirements, I’m pretty sure they’d work fine with either vintage (Dynaco) or modern tube amps in the 60-75 watt RMS per channel range, and there are a lot of candidates out there.

The majority of us mid-fi and upper mid-fi folks probably have transistor amps, class AB in that range, and I went from a nice vintage Sansui AU-919 (100 RMS per channel, very low distortion) amp to a modern class D (Wyred4Sound) and don’t regret it a bit. So I hope you get a chance to try it with something like that. Pehaps the Wyred4Sound folks would even lend you a demo model to test.

I’m looking forward to the review.


I hope these sound as good as the technology that appears to be behind them.
@Torq; I can’t think of anyone who’d be more likely to offer a truly balanced review of these very interesting ear-speakers. I am truly looking forward to your thoughts on how this new implementation stands up to (or exceeds?) the AKG1000, as the AKG is one if the few headphones I regret not buying when I had the opportunity to do so.

I recently made reference in another thread to the AKG1000; but when doing so, I’d not even the slightest hint that a similar headphone was again in the works (at least in appearance and functionality).
Could this “back to the future” endeavour, by a company that seems to know a good thing when it sees/hears it, have managed to get this difficult concept implemented well enough to make a real hit in the new (and crowded) high end headphone market?
I’m betting a good bit of $ went into R&D for this offering, even if the concept was tried by AKG many years ago.
The exceptional resurgence of headphones in the audio world may finally have made room for these beautifully intriguing ear-speakers…let’s just hope the SQ matches the concept!

PS: I hate to bring up or even guess at what these are likely going to cost, as the AKG1000 was one of the most expensive HPs in its day.

But with the price of flagship cans from all companies being what it is today, if this HP is able to achieve a SQ that even approaches the high end of the RALL ribbon tweeter (especially in the bass frequencies), then this piece of gear could really be something to write home about…regardless of cost.


Did you ever listen at any length (or at all) to the AKG1000?