Gramophone Dreams 32: RAAL-Requisite SR1a headphones

Tell me now: When you're there in the scene, watching Lord Voldemort chase Han Solo through the Cave of the Klan Bear, how often do you notice that the sounds you're experiencing are being pumped at you from five black-painted room boundaries, while the flickering-light images approach from only one? Moreover, in a parallel, more quotidian reality, you're sitting upright in your seat, noisily chomping popcorn while absorbing—and processing—massive amounts of sensory data: Did you ever consider the sensual, mechanical, and psychological complexity of a moment like this, and how fundamentally unnatural it is?

What I love most about cinema is how easily and effectively my brain lets me experience being there in the bed with Brigitte Bardot in Les Femmes (1969), or there on the platform of the train depot during the opening sequence of Once Upon a Time in the West (1968). My memories of both places remain vivid.

I confess, I do not understand how my mind can convert marginally realistic sounds and two-dimensional flickering-light images into me being somewhere else. But I do have this memory of my 3-year-old daughter putting a cookie in the door of our VHS player. When I asked her why she did that, she looked at me and said, with absolute matter-of-factness, "I'm feeding the Little Mermaid." It was then I realized: We are wired from an early age to assemble extremely abstract data into powerful conscious realities. This reality-forming process appears to function pretty well no matter how unnatural or abstracted the data it's working with.

Whether I'm reading a book, watching a movie, or listening to music files, the success of my brain's reality-construction depends not on the quantity or quality of data, but instead on my ability to focus my attention on the data as it is presented. The more complete my focus, the more complete my experience of a constructed reality.

I remember my college anthropology teacher explaining how, almost a century ago, explorers filmed a tribe of indigenous Melanesians. When they projected the moving images on a screen, no one in the tribe recognized the chief or his wife or anything that resembled their world. Why? Because they had not yet learned to decode the pictographic language of cinema. Because they had never fed the Little Mermaid.

And of course being an audiophile means I've spent my life staring at an equipment rack between a pair of wood boxes—watching whole operas, Horowitz at Carnegie Hall, or a sweaty Tina Turner singing "Proud Mary." I saw all this because I've spent a lifetime learning to "see" musicians both inside and outside the speaker boxes.

All this cranial-nerve anthropology brings me to the chief question of this column: Is listening to music with headphones really more difficult or "unnatural" than reading a book? Watching a movie on a flat screen? Or staring at the space between wood boxes? Or rather: Is the art of headphone listening something many audiophiles of a certain age have never learned to do—like Gen Z never learned to sit in a sweet spot staring between giant speakers? Well folks, it's never too late for old dogs, because I'm pretty sure I've found a unique non-headphone headphone—one that will instantly satisfy both headphone connoisseurs and stubborn contrarians: the RAAL-Requisite SR1a's ($3499). These radical high-tech contraptions sit lightly on your head and neither cover your ears nor put pressure on your pinna. Plus! They image outside and away from your skull—similar to floorspeakers!

Are you ready?

RAAL-Requisite SR1a headphones
I must start by introducing Aleksandar Radisavljević. He's the founder and chief engineer of Serbian manufacturing company RAAL Advanced Loudspeakers, established in 1995, which manufactures a range of dipole ribbon tweeters (footnote 1). Aleksandar is also co-founder and director of R&D and manufacturing for Requisite Audio Engineering of Ventura, California, which is responsible for the creation of the RAAL-Requisite SR1a ribbon headphones, which the company describes with the trademarked descriptor "Earfield Monitors."


To the best of my knowledge, the RAAL SR1a's contain the world's first and only full-range, pure-ribbon drive-units. To qualify as a pure ribbon, the diaphragm must be a thin, rectangular strip of metal foil, attached only at its narrow ends and energized by rows of permanent magnets at its sides. The diaphragm of a pure ribbon is not attached to a film substrate, as with Magnepan's quasi-ribbons or various manufacturers' air-motion transformer tweeters. The SR1a's design aesthetic relies heavily on laser-cut stainless-steel rectangles and thick buffalo leather. To situate the RAALs properly on my head, I needed to adjust the length of the broad leather top band and the narrower leather back-of-head band. These two bands combine to center the twin 3.77" × 0.75" (95mm × 19mm) open-baffle ribbon-drivers on the entrance to my ear canals.

Along the front edge of each SR1a baffle is a 0.65" × 4" roll of red-orange memory foam wrapped in Italian lambskin suede. That foam-and-suede roll keeps the SR1a off the head and away from the ears. The back part of each earpiece features a gusseted pentagonal wing made of what appears to be lenticular gray-black carbon fiber. That "wing" serves as a waveguide while increasing the area of the ribbon's baffle, allowing for deeper bass.


The SR1a's weigh 15oz (425gm) and come packed in a Pelican case. The RAAL ribbon's natural impedance is a near-dead-short 0.018 ohm. Therefore, they need to be driven by a 50–150Wpc loudspeaker power amplifier (not included) via an impedance-matching interface box (included). This 2" × 5" × 7" ventilated black box contains banks of power resistors that bring the SR1a's apparent load up to approximately 6 ohms (fig.1, footnote 2). The output of this interface box must be connected to the SR1a headset via a 7' Y-cable with a female XLR connector (use of which prevents the owner from accidentally connecting the RAAL headphones directly to the output of a headphone amp, with guaranteed bad results). Also included are two 2' pairs of banana-to-banana cables for connecting the output of your power amplifier to the input of the interface box.


Fig.1 RAAL-Requisite SR1a headphones, electrical impedance (solid) and phase (dashed) (2 ohms/vertical div.).

The RAAL-Requisite SR1a's, which come with a 5-year warranty, are not only the world's first full-range pure-ribbon transducer; as far as I know they are also the world's first headphones that are repairable by the user. The SR1a ribbon drivers are encased in a unique "cartridge" that simply slides in and out of the headphone shell. No tools are required, it takes just a few minutes, and electrical contact is made automatically. These field-replaceable ribbon cartridges cost $199 each or $350/pair.

Cupping and chambering
Beyond their unprecedented full-range ribbon-ness, the RAAL-Requisite SR1a headphones are distinguished by their off-the-ear-ness. This is important: It means their sound character is not manufactured or controlled by a circular padded acoustical chamber surrounding the listener's pinna—like virtually all other over-ear headsets. This is important because all circumaural over-ear headphones have one unsubtle, unnatural, and unavoidable listening component: They mechanically cup our ears, and we can feel them doing this cupping the whole time they're on our heads. (If you cup your hands right now and place them snugly over your ears, you'll experience the resonant seashell-like sounds that result from this cupping.) This air-tight pressurizing is also called "chambering," which is how over-ear headphones make bass. The problem is, this audible circumaural cupping and chambering mask detail and compress lower frequencies.


Cupping is what tells my brain that sound is being pressured into my ear canals. Even when I close my eyes, my awareness of cupping shuts me in and encourages me to imagine the band is playing inside my head. (Headphone-haters hate when that happens.)

Off-the-ear headphones like the RAAL-Requisite SR1a's and the JPS Labs Abyss AB-1266 Phi's do not cup or chamber: Instead, they hover near the listener's ear, which means they deliver free and open reproduction that requires very little brainwork to reconstruct.

Amp requirements
Aleksandar Radisavljević explains why the SR1a headphones need a 100Wpc amp:

"Since there is already a 10:1 (or higher) ratio of cable to ribbon resistance, this means that the ribbon will not be controlled by amplifier damping. (It was clear from the beginning that ribbon excursion and damping control must be accomplished by passive means: using small amounts of acoustical resistance.)

Footnote 1: RAAL Advanced Loudspeakers d.o.o., Djordja Simeonovica, 419000 Zajecar, Serbia. Tel: (381) 64 144 1111. Web:, Requisite Audio Engineering, 2175 Goodyear Ave, Suite 110, Ventura, CA 93003-7761. Tel: (818) 437-0779. Web:

Footnote 2: Using the Dayton Audio DATS V2 system, John Atkinson measured the impedance magnitude and electrical phase angle of the RAAL headphones with them plugged into their adapter box. The load seen by the amplifier varies between 5.8 ohms below 300Hz and 9.8 ohms in the high treble. It is almost a pure resistance, however, the phase angle measuring close to 0° across the audioband.


Anton's picture

It seems that would offer easily achieved upgrades and even a low cost way for people to experiment with aftermarket mods.

It's out of my budget but seems reasonable and loads of fun to be had with it.

I hope you get to keep it around and we can see its evolution.

Thanks for a killer 'turn on' to a fascinating product!

Bogolu Haranath's picture

Another nominee for Stereophile 2020 product of the year award, RAAL SR1a ribbon headphones :-) .......

Anton's picture

It went on my "Lotto" list.

Bogolu Haranath's picture

May be HR could also review the MYSPHERE 3.1/3.2 headphones ($4,000) ........ HR mentioned about them favorably in his CanJam NY 2019 report for Inner/Fidelity :-) ........

JRT's picture

One advantage of the Mysphere 3.2 is that it does not need as much amplifier to work well.

Bogolu Haranath's picture

Both MYSPHERE 3.1 and 3.2 models should work well with conventional headphone amplifiers ........ Like the RAAL, they don't need amplifiers/integrated amps, that can drive loudspeakers :-) ........

JRT's picture
Bogolu_Haranath wrote:

"Another nominee for Stereophile 2020 product of the year award, RAAL SR1a ribbon headphone"

Seems so.

jeffhenning's picture

...the Benchmark AHB-2 to drive these things. At least, that's what he said last year.

In any event, man, the whole package is a lot to spend on headphone listening and a lot in general, mastering engineer or not. This is not an insignificant amount of kit for headphone listening.

Possibly, if I could write the system off as a business expense as an audio engineer at a ridiculously successful studio. Even if I won the Powerball, these would be really, really low on my list.

Would love to hear them, though.

Glotz's picture

Perhaps that was the reason why he heard them 'brittle and bright' on some recordings?

I wish I could read JA2's follow-up, as I can't find the issue nor remember all of the findings, outside of the RC blurb.

More to the point, $3k is pretty inexpensive for the company is competes with. It's not easy to compete with 5-figure amps at this price point.

That being said, I did purchase the Benchmark HPA-4 (LA4 with headphone amp), and it is fantastic and my feelings very much echo the thoughts in several pubs.

Straight wire with gain, baby!

partain's picture

Just a quick comment on the natives not recognizing the chief.

Ortofan's picture

...a seasoned headphone connoisseur who has been in the game for a long, long while, is a confirmed music aficionado and already owns the venerable Stax Lambda Pro earspeakers.

As a replacement, and with a budget of about $3,500, he is considering the Stax SR-L700 MKII paired with either the SRM-007 TII (tube) or SRM-727II (solid-state) driver units.

Would such an individual be likely to find the sound quality of the RAAL-Requisite SR1a to be astonishing, revealing, revelatory, revolutionary - and, above all, a must-have?

Anton's picture

Perhaps, maybe, yes, to quote Kraftwerk.

It's up to the audiophile you mention.

Bogolu Haranath's picture

Yes ..... If that audiophile is also rich :-) .......

Bogolu Haranath's picture

BTW ..... Why not that audiophile get both tube and transistor drive units with those Stax headphones? ...... He/she can have both flavors :-) ........

Bogolu Haranath's picture

Or .... That audiophile could go for the new Stax flagship SR-009S electrostatic headphones with the matching SRM-007T tube amplifier and SRM-007S transistor amplifier :-) ........

Herb Reichert's picture

I am listening to the SR-009S right this minute


Bogolu Haranath's picture

Great ... Looking forward to reading that review ........ Try them also with the matching Stax amplifiers, if you aren't already doing so :-) .......

Ortofan's picture

... the finest headphones (or earspeakers) on Earth, you can then use them as a reference transducer with which to conduct listening evaluations for your upcoming survey of cables.

Note that the cable for the SR-009S is silver-coated 6N copper. You should inquire as to whether or not the conductors are twisted - judging by the flat cable, it would appear that they are not. But don't do it while you're harbor-side in Cannes, lest it disturb your reverie.

Bogolu Haranath's picture

Wait .... We want HR to review the Warwick Acoustics Aperio electrostatic headphones with matching DAC/headphone amplifier ($24,000, reviewed by Hi-Fi News) ....... Then, HR can tell us which headphones are the world's best :-) .......

Herb Reichert's picture

the SR-L700s just arrived


Bogolu Haranath's picture

I'm trying to guess which amp HR is gonna like ...... Tube or transistor? :-) ........

Ortofan's picture

... of my seat.

Bogolu Haranath's picture

'Watchin' the tide roll away'? :-) .......

Bogolu Haranath's picture

Schiit Audio just came up with an integrated amp to specifically drive the RAAL ribbon headphones, Jotunheim R ($799) ......... May be HR could review that integrated amp? :-) ........

Herb Reichert's picture

of course (it is on its way)

Bogolu Haranath's picture

Looking forward to reading that review, including comparison with other amplifiers :-) ......

JRT's picture

Thanks for the well written review.

Bogolu Haranath's picture

The 'Cupping and Chambering' problem HR describes above in his review, gets even worse with 'closed-back' versions of headphones ...... That is one of the reasons why, most of the headphone listeners prefer 'open-back' headphones :-) .........

dcrowe's picture

I have the immense pleasure of owning the SR1a and using it with a Schiit Vidar which has adequate power and current for my listening. I do look forward to obtaining the AHB2 with DAC3 though.

agb's picture

Has no cupping problems, none, nada, and even though it fits into the ear (lightly for me), no bass pressure build up. OK, I recognize it is a "different" type of earphone. In my experience, two years or more after its release, it still trounces many other would-be's I have here. Lastly, I don't miss the weight like a brick on top of my balding head. There's a lot to be said for small and light, the great sound - and portable. It being what it is, it's magic.

Incidentally, worked with Julius Futterman for a while who also built me two ESL headphone amps for the two Staxes I had back then. One didn't sound like the other.

Whatever headphones do wrong, speakers always had a tough time catching up to them. And regardless the cost and expense, they still do.

Let's face it, with few exceptions, the room screws up the sound, one way or another. If not the room, it'll be your wife.

Earphones are hardly perfect...rooms far less so.

jww1's picture

Your favorite headphone amp? May be a silly question but By what means do you accomplish this?