Raal Requisite SR-1A

Discussion in 'Headphones' started by Zhanming057, Dec 31, 2018.

  1. Zhanming057

    Zhanming057 Almost "Made"

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    [​IMG]

    Figure I'd start a thread here with some early impressions, since Danny is finally sending out review samples for these. The short of it is that other than some questionable stuff coming out from China, these are the first aluminum ribbon driver headphones. Because the internal resistance of the aluminum band is so low and because the product is essentially a pair of tweeters being press ganged into full frequency range duty, they require an external 4 ohm adapter box for tuning and protection of the amplifier.

    The box makes these things incredibly hard to drive - think 50 watts/4 ohms per channel at a minimum, and 125w+ as a good target to hit. They will actually draw 50 watts on peaks if you like higher listening volumes, so tube amps outside of a few select designs (KT88's, KT150's, strong 845's?) simply won't be able to feed them properly. That said, if you can drive them off tubes the pairing works like a charm.

    The headphones themselves are light and comfortable. Extensive use of carbon fiber means that the drivers have better weight distribution than they look. Fit is K1000-style with two foam pads and a soft overhead leather band to spread the weight around. I can wear these for hours with zero fatigue which really can't be said for the LCD-4 or the Abyss 1266's. The cable is detachable with dual 3.5mm connectors and actually accounts for most of the load from the adapter box output: more than 90% of the 0.2 ohm load is from the cable and not the ribbon.

    One would think that ribbon drivers can't deliver proper bass but surprisingly, bass is not an issue at all. It's punchy and well-defined, very much on par with the 1266 phi's, a little lean compared to something like the LCD-4. Treble is definitely the strongest point on the SR1A with incredible speed, clarity and massive dynamics. The speed is almost a revelation of how slow "normal" headphones are in terms of rapid transitions. I'd go as far to say that the treble delivery on these with the Nagra INT is a meaningful step up from the likes of the 009/BHSE combo or even the HE90. It's that good.

    Midrange isn't quite recessed per se but I feel that it's a relative weak point of the Raal's. The SR1A's midrange has enough resolution but the overall structure is a little soft, especially when you compare these to a reference-level midrange such as that of the Mysphere 3.2's. Vocals aren't intimate in the way that the Utopia or LCD4's are; the lightning fast transition speed is somewhat of a detriment in that regard. That said, I had no issues enjoying vocal-heavy tracks, and the spaciousness of the open design leads to an almost "live house" feel that I can get behind.

    So far I've tried them with a couple of integrated and power amps, and my favorite combo is probably a tie between the Audio Research REF75 and my Nagra Classic INT. Amps with midrange emphasis helps with overall coherence as do amps with a bit of treble rolloff. The more neutral Simaudio power amps felt slightly too polite with the Raal's, and Spectral's house sounds delivers a bit too much energy into the treble range.

    My impression now is that people are going to have a love-hate relationship with these not unlike that of Spectral. A lot of it comes down to how much treble energy one feels comfortable with and preferences between the free-floating bass signature of ear-mounted speakers and the larger bass quantity of high-end planars. That and actually owning an amp that's powerful enough to drive them.
     
    Last edited: Jan 9, 2019
  2. m17xr2b

    m17xr2b Friend

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    So this is a 7K hp/amp setup minimum? 3.5K for the headphones and upper high end speaker amp to drive by the looks of it. You have a 15K amp and they sound great, the other amp you like has KT150 tubes only made in russia current production, no NOS available. Hard to say it's a headphone when it needs harbeth P3ESR level of power.

    Would these be the craziest headphones of all time? Not being able to use any headphone amplifiers would be a first. I'll be curious to have an audition if it shows up at canjam, chances are the price might be worth it, 7K for an Abyss setup is understandable because it delivers.
     
    Last edited: Dec 31, 2018
  3. Zhanming057

    Zhanming057 Almost "Made"

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    I don't think they need that much (expensive) power - I have the Nagra because I run all of my headphones on it, and while it "only" delivers 100 watts at 8 ohms, the quality of output is superbly clean and I can even drive IEMs on the Nagra without much noise. But you can probably get reasonable results with a cheap and powerful integrated unit since the Raal's are power hungry more than anything, and that's something I plan to test in the near future.

    I agree that these are a much more radical departure from "normal" headphone design norms than anything I've seen. There's a "we'll build the best headphones ever and practical considerations be damned" vibe to them and I can definitely appreciate the engineering and risk-taking from Requisite Audio.

    I'm going to ask Danny about Canjam plans. He was at RMAF so chances are he's going to at least send someone over. I'll probably bring my pair to Canjam NYC if he's not around for that.

    Edit: Here's a photo of the adapter box and headphones alongside my rig!

    [​IMG]
     
    Last edited: Dec 31, 2018
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  4. MuppetFace

    MuppetFace Sultana of Seafoam Green - Moderator

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    I’ve been keeping an eye on these things for what seems like the better part of a decade now. Or at the very least, the project that was to become this (these look quite a bit fancier than I remember).

    I know I’m not alone there. Ribbon headphones have fascinated planar-heads forever; you can see talk of them in some of the oldest threads on head-fi and others.

    Will be positively strange to finally hear these things.
     
  5. bengo

    bengo Friend

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    Interesting tech.

    Vidar 200Wpc/4Ohm Class AB £700
    Nord 500Wpc/4Ohm Class D £700
    Pick your poison.

    Probably someone could design a specialized HP amp which can drive these directly (without the transformer, or whatever's inside that box).
     
  6. 9suns

    9suns [insert unearned title here]

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    Yup, that would be something incredible, but it would have to be a monster transconductance amp, and for optimum results paired with a a similar DAC (kinda like the Bakoon DAC and it's "Satri link" outputs to have an all current drive setup).
     
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  7. Zhanming057

    Zhanming057 Almost "Made"

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    That's a pretty interesting idea. Although you'd still want a way to physically prevent the headphones from being plugged into a "normal" amp, and an all current drive system will be even more of a specialized product than a strong power amp. Maybe something to be sold as a special bundle with the cans would work.

    Still really enjoying them, with the strap set up just right I can wear them without the stabilizing rear strap, which makes them just as comfortable to wear as the original K1000's.

    [​IMG]
     
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  8. Armaegis

    Armaegis Friend

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  9. 9suns

    9suns [insert unearned title here]

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    That would be a solution, however not the most elegant AFAIK, as the amp also has an I/V converter inside to be used with "regular speakers".
    A true current drive amp has no damping factor, and it's power doesn't double if the impedance halves, however it can only be used successfully with speakers or headphones with a purely resistive impedance.

    An amp that would work with the Raal headphone, should have (according to the power requirements provided by @Zhanming057 ) 125 watts, and, to be used directly, be capable of doing it at 0.2 ohms impedance (the black box provided uses caps and resistors to up the impedance to 4 or 5 ohms to allow the use of more common amps) constantly without going on fire. That would be quite a monster amp just for the headphones.
    A DAC with current outputs like the Bakoon one would be the icing on the cake for the all current drive setup.

    Edit: Also, the amp can't have turn on/off transients and must have 0mv DC offset, as ribbons are extremely sensitive to it. There's plenty of info at the Apogee Forum and some Diyaudio threads about direct driving ribbons, very interesting reads.
     
    Last edited: Jan 1, 2019
  10. dBel84

    dBel84 Friend

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    As MuppetFace mentioned, ribbons have been the allure of planar heads for decades. RAAL was not the first to hint at a commercial ribbon headphone, Transmission Audio first teased the world with images of their driver back in 2010 [​IMG]

    although you might argue that RAAL had a working prototype in 2008 already

    [​IMG]

    Sadly for us headphone geeks, Transmission Audio didn't pursue their headphone product but did produce an incredible high frequency driver for cars

    [​IMG]

    @MuppetFace is one of the few people to ever own the piezo / heil headphone from TakeT


    Fun times with Quad, Raal and all the others stepping into the market. Funny to think that I find most pleasure in the simple vintage yamaha's that started this revival with Wualta and his EPIC thread

    ..dB
     
  11. Zhanming057

    Zhanming057 Almost "Made"

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    Ailun has a ribbon cable open back headphone on sale in China since late 2018 for about $300. It's not very good though, at least from what Ive heard. It must be pretty difficult to tune these things if the project from Real stayed in development for so long.

    Between Real and Mysphere, I've been quite impressed with the new crop of ear mounted speakers. Even more for Real because it's such a different design and coming from companies with no headphone design background.
     
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  12. taisserroots

    taisserroots Friend

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    It's surprising that it has abyss levels of bass despite being a suspended design with no earpads to create a seal.

    Given that they've adapted a tweeter for this, seems a bit weird that it has this design and a warm tilt. With good subbass extension
     
  13. Zhanming057

    Zhanming057 Almost "Made"

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    I wouldn't call it "warm", more of a "punchy but neutral". The bass extension is great but you're not getting Abyss 1266 levels of bass quantity. That's probably just a fundamental design constraint though, and of all the no-earpad designs I have heard, the Raal's have the best bass hands-down.

    My understanding is that they're getting the bass from allowing the ribbon more capacity to move and push more air volume to deliver at lower frequencies. There's definitely a bit of mid-range performance tradeoff but it's a fascinating take on the issue.
     
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  14. Zhanming057

    Zhanming057 Almost "Made"

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    I recently got some more time with the SRH1A on a couple power amps against the Abyss, the Shangri-La Jr and the 009 + Kgsshv Carbon combo. This might be a bit of a hot take, but IMO if you're (1) not chasing a particular bass-light signature (2) okay with the general open-ness of ear mounted speaker designs and (3) either own or is open to buying a strong power amp, the SRH1A almost strictly dominates top tier electrostat systems.

    Compare to the 009/Mjolnir Carbon system, the SRH1A on the Octave V80SE (which is, granted, about $3,000 more amp street price wise) has better treble extension, better speed, almost incomparably better bass extension and quality. The tubes slow down the SRH1A just a bit and adds much appreciated warmth to the lower midrange. What you do lose with the SRH1A is the intimacy of regular cans and the 009 in particular, and you can get more bass quantity out of very strong electrostat systems (e.g. non-jr Shangri-La).

    I listen to a lot of electronic music and the SRH1A with the DMA400 monoblocks is absolutely amazing for that genre. The speed of the treble response is almost surreal and extremely accurate. Surprisingly sibilance is quite well-controlled and at no point did I feel that the treble was anything less than smooth. This is still quite an extreme pairing and Spectral exposes the thin-ness problem with the SRH1A's mids that tube amps hide very well. For classical and orchestral music even relatively cheap KT150 amps perform quite respectably with the SRH1A, it's mostly a matter of how much treble response is being traded off for warmth.

    The TL,DR is that if you're considering a high-end electrostat system, and especially if you like fast treble but wished that the Stax's had more bass energy, try to spend some time with the SRH1A before pulling that trigger.

    Edit: Danny won't be at Canjam NYC but I will be and I'll bring the SRH1A if I can figure out what to drive them with. I'm not even sure if I can find an amp that delivers enough power at Canjam.
     
    Last edited: Jan 7, 2019
  15. Zhanming057

    Zhanming057 Almost "Made"

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    Aleksander at Raal has asked me to post a few words about amp pairings with the Raal SR-1A (yes, that's a name change from the SRH-1A).

    An amp that is only rated at 100w at 8ohms will run out of excursion on bass-heavy tracks with the SR-1A and display clipping. I tested this on my Nagra Classic INT and didn't notice an issue compared to the DMA150 at what I would consider listenable volumes, and clipping did not happen when the amp was pushed to the max volume. That said, it's possible that Nagra is rating their gear conservatively, or that the amp is pushing out significantly more than 100wpc on a 4ohm load. As a general guideline though it's probably a good idea to shop for an amp rated at much more than 100wpc at 4 ohms for the SR-1A.

    All development, voicing and setup of the SR1A, was done with the Benchmark AHB2 amplifier and Benchmark DAC3L. This is also the "reference" combination that Aleksander recommends for the SR-1A. I have not tried this combination although it's possible that the SR1A will be at the Benchmark booth at Canjam with the AHB2. My take on the AHB2 is that it's quite good value for the money, if a little polite and a tiny bit hot in the treble range.

    Danny runs his pair on the Bryston 7B³ monoblocks and also with custom-built KT88 monoblocks rated at 120wpc.
     
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  16. Zhanming057

    Zhanming057 Almost "Made"

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    Forwarding Alexsander's post from Head-fi to here:

     
  17. Garuspik

    Garuspik Tovarisch Ukrainian Terminator MOT - Verum

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    Unlikely I have a chance to hear those headphones but almost everyday I listen to my speakers with Raal 140-15D tweeters and consider them to be among the best non-dome tweeters ever.
     
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  18. Zhanming057

    Zhanming057 Almost "Made"

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    Raal is in Serbia and as far as I know they have an engineering unit and is finalizing the first production run, so if you were to make that trip you might be able to demo both their tweeter lineup and the SR1A. Alternatively, Alexsander can probably send you a demo, although I'm not sure how complicated shipping is from Serbia to Ukraine.
     
  19. Zhanming057

    Zhanming057 Almost "Made"

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    [​IMG]

    Another day, another system for the SR1A :) Waiting on my production version for the big group photo.

    On the trip to pick up the preamp I had a chance to try the SR1A with a few "cheap" systems. The cheapest 100w+ integrated at the store is the NAD C368 (MSRP $900, street price $700-ish). The build-in DAC on the C368 is awful and borderline unusable (or it could have been broken, it was seriously that bad). However, moving to a Berkeley Alpha DAC series 2 resulted in a surprisingly listenable system. The pairing compared not unfavorably in resolution and has superior dynamics to driving the Abyss 1266 phi's through a WA7 or nx03 with a similarly strong DAC. A sample size of one is not quite representative but I would expect the SR1A to be very listenable on power amps in this price range.

    The Hegel H190 is a much more expensive unit, but incorporates a DAC that seems to punch at or above its weight with a light, clean and smooth signature, if a tiny bit lean and indecisive compared to stronger stand-alone power amps. The headphone jack is actually driven by the same circuitry as the taps and does fairly well with both the Ether C Flow and LCD3. The SR1A is pretty good on this amp - transparent, clean, with pretty good resolution for the price of the system. If you're looking for a simple, no-fuss solution for the SR1A that also works with normal headphones, the H190 seems like a solid value proposition.

    The Hegel Rost shares the H190's signature but has less grunt. On only 75 watts of output at 8 ohms you can feel that the SR1A is struggling a little with bass extension, although loudness was not an issue for me. For the price difference I think that the H190 is clearly the better option, but I wouldn't mind using the Rost with the SR1A's on a day-to-day basis.

    Having spent time with the SR1A's on the Spectral setup, my views on the SR1A's midrange have become a bit more nuanced. Conventional wisdom on headphone midrange performance values clarity of imaging and "lushness" which is associated with slightly warmer tuning. Even if midrange frequencies are not emphasized, the slower response speed of dynamic and planar drivers is what we are generally comfortable with as headphone enthusiasts.

    The SR1A's are not part of that comfort zone. Is a neutral, accurate, hyper-fast, and almost too revealing midrange worse than a slower, thicker, lush, more "emotional" midrange? If you're someone who likes to pair headphones with 300b amps and enjoy that kind of euphoric, darker vocal signature, the SR1A on a strong solid state amp is the absolute opposite of that signature, and you probably won't find the pairing pleasing. For someone more receptive toward a neutral signature and leaner imaging, I do think that the SR1A's have the capacity to be a vocal powerhouse, especially with extraordinary well-mastered files.

    Assuming that everything is being driven exceedingly well, the Mysphere 3.2 is still my choice for the strongest midrange imaging and doesn't trade off much resolution against the SR1A's on any system. The Abyss 1266's midrange is arguably a tiny bit better in imaging, thicker and more full-bodied but isn't quite as revealing as the SR1A. And while the LCD4 is the least resolving, thickest and most "lush" of the bunch, I don't think that resolution or imaging is a substantive concern with any of these headphones, if you can drive them to their full potential.
     
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  20. Tachikoma

    Tachikoma Acquaintance

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    Maybe you'd be interested in these at some point: https://www.kurada.co.jp/kd-p1

    They sounded pretty good to me, but I'm a terrible critical listener.
     
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