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

They might, it’s hard to say without trying them. From what I’ve gleaned so far, particularly in reading a fair bit from the designer, the quoted power requirements (and need for stability/sustained drive into low impedance loads) are real and should be taken seriously.

If they were simply low-sensitivity dynamic transducers, I’d be inclined to think the same way - but they’re not and the reported issues with under powering* them are not just about lack of authority and lower playback levels. Regardless, it is experimentation I will leave to someone that already has such amplifiers readily available and that is similarly interested in the SR1a.

They might, but for several reasons I am very unlikely to find out. Of course, if you’re interested in how the SR1a pair with their amplifiers, then RAAL-requisite offer an in-home 14-day evaluation period so you could test them for yourself in your environment and get a much better impression than anything you might glean from my inane drivel.

*While the dual-Aegir solution is technically underpowered, I am giving that a go on the basis that a) I’ve heard it’s a combination that does, in fact, work rather well and b) because I am used to Schiit under-stating, or under-rating their power amplifiers.


I have not, unfortunately.

However, I have listened at length to the MYSPHERE 3.1, which was developed by a team including Heinz Renner, who led the development of the AKG K1000. The MYSPHERE is remarkable in its own right, and quite comparable to the SR1a.



There was (and is) the MySphere 3.x, which I believe actually involves people formerly involved with the development of the AKG K1000 (I see @pavi beat me to that!). And now there’s the SR1a, which has some similar goals, and some that are just new and different.

Those, and even the AKG K1000 (if I ever find a used set that doesn’t have issues at odds with the asking price I’ll buy them), offer the potential to significantly simplify (and improve) my listening experience, so I am very keen to see how they fare.


Interesting. What do you think is inside that adapter box that presents the nominal 6 ohm load? Given that ribbon drivers are way different than electrostatics, it can’t be what you’d find in the typical STAX or Koss adapter boxes.

And where does the heat from that power dissipate?

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A pair of large arrays of high-wattage resistors (9 rows of 8 resistors, presumably 4 resistors per row per channel, off a thick solid-copper bus, with a pair of transformers (one per channel). It presents a 5.6Ω (I rounded up) ohm load to the amplifier and 140w of heat-dissipation, instead of the 0.2Ω of the ribbons themselves.

It appears to be passively air-cooled, and the interface box requires some space around it to let that work correctly.

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And there you have it…this 100 watt brain zapper reduced even the Mighty @Torq to inane drivel! What will it do to those of us who are already challenged in staying on topic (@Pennstac…can you help)?


I can’t blame the SR1a for that quite yet … it’s still on the delivery truck …


Back in the day, The Grateful Dead (and later Phish) had the reputation of being “bands that sound great when you are high” – otherwise they were too loosey-goosey. So, the key to an optimal audiophile experience may be to induce an altered state of consciousness so everything sounds great…and this one might just do it…


Seems you’re a step or two up on us peons who are just hearing of these new ear-speakers.

@Torq; You’re aim with some used AKG 1000s has been mine for years.
Unfortunately, anyone selling their set usually seems either to have worn them down/out or ruined the purchase appeal in some other manner.

If they do happen to be in great shape, some of their owners/sellers seem to think $6500 is a fair price for headphones that sold new for $1100!

(I’m afraid to look up the cost of these new models.)


$3,500 on the RAAL website. Way out of my range but certainly in the realm of true hi-fi.


@Torq explained perfectly, but I’d put them with a layman’s term.

Below is what the inside of SR1a adapter box actually looks like:

And structure-wise it’s surprisingly similar with stax adapter box (I don’t mean their current amps … but discontinued SRD lineup which is used with speaker power amps). Look at this:

Signal-wise, sr1a box seems to serve as (1) impedance match via transformers, (2) voltage-current transformation – my bet is it’s rather similar with stax srd in the end – and (3) shelving analog EQ to tame trebles.

Speaking of the last element, RAAL said the box had the transfer function – Vout(f)/Vin(f) – as the following:

With the following input impedance curve (power amp sees this curve):

Anyway, this headphone looks very interesting. But I am thinking RAAL targets high end speaker owners rather than headphone-first listeners… For most headphone listeners it may require too much: 3.5k (usd) for headphone and 3-5k power amps (except Schiit offerings like Vidar or Aegir x2 or maybe Ragnarok 2). Overall cost requirements will resemble that of SR-009+matching Amps in my opinion.

Of course I am one of them who are waiting for @torq’s review! :smile:

@pavi : Can I ask your preamp gain setting for modern pop recordings? (DR<10 and zero or near-zero headroom stuffs) On calculation, 4V dac output and 22+6 db Aegir x2’s gain will allow preamp gain up to -12db before limited by current (ignoring Schiit’s too conservative rating haha). Just curious about how real users feel in terms of overall perceived loudness.


By the time the Grateful Dead reached Workingman’s Dead and American Beauty, they were hardly loosey goosey. Oh for days of Anthem of the Sun and Aoxomoxoa. There, not a help at all for staying on topic.

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Fortunately, you can get good and adequate power - 100 watts RMS per channel - on the used market for about a tenth of that. In the 70s and 80s, tube amp power was on the wane, and transistor-powered amplifiers were going up-market in an environment where they weren’t competing with computers as the kings of home electronics. Companies like Marantz and Sansui were putting out amps that hold up today as very high quality. Since they don’t have the cachet of tubes, you can often find good examples in local classifieds, on eBay, or audiogon. There are still local electronics shops that can go through them and replace any aging capacitors and make sure the controls work cleanly.

That Sansui AU-919 integrated that I have weighs 54 pounds, is class AB, Total harmonic distortion: 0.008%, Signal to noise ratio: 74dB (MC), 90dB (MM), 100dB (line). It does want an 8 ohm nominal load, but we all know that speaker loads vary significantly with frequency, and I haven’t found any issues with it driving my old STAX SRD-6 adapter or any speakers I’ve paired with it.

I keep it for a backup, just in case I ever need it…


sadly, one of my aegirs went on the fritz - and i’m unable to reset the fault. i’ve contacted schiit for help, and am waiting to hear back. when things are back to normal, i’ll test it for you - pretty much only listen to jazz in general.


Yeah, going for old good amps could be very sane and often brings something nice to the table. No doubt! However, I am always wary of such products regarding generalized discussion.

Typically old amps use less negative feedback and less active dc servo circuits. This per se is desirable in my opinion. The problem is that such circuits assume internal parts remain good. I know some followers of a legendary Japanese amp like Panasonic M-22. And I’ve also seen some of them needed to be overhauled or repaired to get things right. Not sure about Sansui or Marantz but I am suspecting product-to-product aging variation to the same extent.

If I go for SR1a, I am not willing to spend that much money. Can’t afford it. :sob: Schiit’s power amps seem more plausible ways – but not sure about how they paired with SR1a. In this regard, @pavi’s report is encouraging and @torq’s (comparative) review can help me too. Nevertheless, reading SR1a threads in various places, it is just a realty that a median SR1a user spends at least $3k-ish (new) in their power amps to drive this headphone.

Off-topic, if Aegir x2 could drive sr1a, then I am hoping Vidar (stereo) could do the same thing voltage and current-wise. :wink:

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That’s too bad to hear that…

The reason why I am requesting modern pop is that generally it has much narrower dynamic range, so that loudness perception is rather stable during the whole track.

For example, Taylor Swift’s Welcome To New York has -0.01 db at peak, -7.7 db on average (rms), and estimated dynamic range is around 5.0 (db).

By contrast, Bill Evans’ When I fall in Love has -0.26 db at peak, -19.3 db on average, and 13.9 db of calculated dynamic range.

For loudness testing purposes, I believe the former is easier to make arguments. :smile:


I got my Sansui for under $300. Overhaul was $150 originally. I used it for about 8 years, and took it in for servicing for about another $175. When you buy a quality older amp, you should budget for some cleaning and servicing.

If you’re looking for something more modern, I just checked Audiogon, and there is a Macintosh MC754 (about 1990), An Emerald Physics EP100.2 SE (model still being produced), Arcam Diva P90 Stereo Power Amplifier (about 2004-2008) all for about $600.

By contrast a new Vincent hybrid is about $2K,

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Well … they arrived yesterday … just in time for me to set them up, make sure they worked, play a couple of tracks … and then head out to a charity fundraiser for the night …

I’ll take a few, basic, pictures in a bit.

Running these out of my reference-chain (RME ADI-2 DAC, SPL Phonitor X) for now, in conjunction with a modestly priced ($600) speaker amp (150w into 8Ω/225w into 4Ω, toroidal transformer based linear PSU, solid-state analog class A/B, THX-certified* - with decent measurements - so likely a fair amount of negative-feedback).

Initial impressions are, well … striking …

The SR1a are doing things that I’ve not heard from a headphone before.

The build and aesthetics are awesome … the best way I can describe it is as high-tech, high-end tooling. Adjustment is easy, and driver-angle has very audible effects on sound and stage.

There is actual stage depth.

Resolution, speed and impact are remarkable - even off this comparatively inexpensive amp.

And they really are neutral.

Interface box is running cool (79℉) even after several hours of, shall we say, “spirited” listening.

Didn’t expect this off such a, comparatively entry-level, amplifier.

I don’t think anything productive is getting done today.


agreed. i certainly don’t have your breadth of experience, @Torq, nor your depth of evaluative skill, but to my ears, this is utterly true.