RAAL-requisite SR1a Ribbon Headphone Review

[eboleyn]

I've had the RAAL SR1a for about 3 1/2 months now. I have heard a few other high-end headphones but for detailed/long-term comparisons own a set of Hifiman HE-6se and HE-500 headphones and some higher-end speakers.

The SR1a are clearly the best headphones I've ever heard, but they do indeed take some quality gear to drive them to their best, though I am going with overkill at the moment. My stack:

1. BluOS CI 580 - Digital source/using CD or higher quality, output as 24/96kHz
2. Behringer DEQ2496 - 63 band digital equalization at 24/96kHz
3. Sabaj D5 DAC - XLR outputs
4. XLR < 1% balanced adjustable resistor level reducers
5. Power amps with XLR inputs:
   • Pass Labs X250.8 (sweeter but still pretty accurate)
   • Purifi 1ET400A (king of accuracy!)

So, yes the stack is quite expensive. I've checked and my listening level is typically not even 1 watt, and only around that when I'm hitting the bass notes in harder tracks, though I'll admit that I am typically a "quiet listening" sort.

As to the cost of the stack, I use it for a high-end passive-crossover speaker setup as well, and the headphones are superior to it. I.e. if I'm willing to do it for speakers, then I'm willing to do it for the SR1a as well. (ok, yes, I *do* have speakers which are superior to the SR1a, but they are active crossover speakers which are in another league of cost for their stack due to the digital processor, multiple stereo amps, etc.)

To be clear, with lesser gear I'd tried them on, they still sound as good or better as the other headphones on that lesser gear, but with the overkill setup their differences become more stark. It just seems a waste to not go all the way with the awesome sound I can get. Why else would I have bought the SR1a then?

Having said the above... I haven't tried dialing in exactly where the "lesser" ends and "overkill" starts, and will probably not try to go there.

On a last note: For my HE-6se headphones I have a Schiit Modius/Magnius stack which should arrive in the next week or so (I have also run the HE-6se on the stack listed above and while they sound good on that, it's much less portable), and I admit to being just curious to try the SR1a out with some appropriate extra resistors added in to see if that will drive them to the quiet levels I use.

 

[The Jniac]

Why do you want that?

I am not quite sure that I understand your question. If you mean why I would want a pair of speakers that measure as perfectly flat at the listening position, the simple answer is that I would not. I would want my speakers to be reflective of the room, such that if I were to make a acoustically-perfect recording of someone playing a cello in the room, and then play that recording through the speakers, the recording and the original performance would sound identical.

In contrast, I would want my headphones to sound identical to a pair of speakers that are perfectly flat at the listening position because, and please try to bear with me on this because in proofreading this I realise that I sound a little crazy, I want headphones to put me inside the music, perfectly reproducing exactly what is contained within the audio data without it being coloured by room characteristics.

I will add that I am getting the impression that you guys are trying to tell me something, as if I am coming across as a complete moron who is failing to grasp something very basic and you are trying to get me to see that without offending me. If that is indeed the case and not just a product of me overworking myself, I would like you to just tell me what it is that I am evidently not getting.

 

[Soniclife]

I will add that I am getting the impression that you guys are trying to tell me something

I'm asking because I didn't follow your logic, and there are plenty of people posting here smarter than me.

In contrast, I would want my headphones to sound identical to a pair of speakers that are perfectly flat at the listening position because, and please try to bear with me on this because in proofreading this I realise that I sound a little crazy, I want headphones to put me inside the music, perfectly reproducing exactly what is contained within the audio data without it being coloured by room characteristics.

The simple way to do the first part of this would be to put a perfectly flat anechoic speaker in an anechoic room, and measure them there. You want the response that your hrtf would give from that?

 

[Shazb0t]

I am not quite sure that I understand your question. If you mean why I would want a pair of speakers that measure as perfectly flat at the listening position, the simple answer is that I would not. I would want my speakers to be reflective of the room, such that if I were to make a acoustically-perfect recording of someone playing a cello in the room, and then play that recording through the speakers, the recording and the original performance would sound identical.

In contrast, I would want my headphones to sound identical to a pair of speakers that are perfectly flat at the listening position because, and please try to bear with me on this because in proofreading this I realise that I sound a little crazy, I want headphones to put me inside the music, perfectly reproducing exactly what is contained within the audio data without it being coloured by room characteristics.

I will add that I am getting the impression that you guys are trying to tell me something, as if I am coming across as a complete moron who is failing to grasp something very basic and you are trying to get me to see that without offending me. If that is indeed the case and not just a product of me overworking myself, I would like you to just tell me what it is that I am evidently not getting.

I think what they're getting at is that in speaker research it has been shown that ideally you want to reproduce a flat frequency response in an anechoic chamber. When in an actual room with reflections the response for that same speaker will not be flat at the listening position. You wouldn't want it to be, it wouldn't sound natural. So for a headphone, which doesn't have the same room interaction, in order for it to also sound natural, like that flat anechoic speaker, you would want it to have a non flat frequency response at your ears to account for the natural shift in frequency response that occurs in a normal listening situation. That is what the Harman target curve and other target response curves are trying to account for. It is the curve which these headphone reviews are using to compare against for accuracy. A perfectly flat headphone or speaker frequency response at your ears/listening position would sound awfully bright.

 

[Ilkless]

I am not quite sure that I understand your question. If you mean why I would want a pair of speakers that measure as perfectly flat at the listening position, the simple answer is that I would not. I would want my speakers to be reflective of the room, such that if I were to make a acoustically-perfect recording of someone playing a cello in the room, and then play that recording through the speakers, the recording and the original performance would sound identical.

In contrast, I would want my headphones to sound identical to a pair of speakers that are perfectly flat at the listening position because, and please try to bear with me on this because in proofreading this I realise that I sound a little crazy, I want headphones to put me inside the music, perfectly reproducing exactly what is contained within the audio data without it being coloured by room characteristics.

I will add that I am getting the impression that you guys are trying to tell me something, as if I am coming across as a complete moron who is failing to grasp something very basic and you are trying to get me to see that without offending me. If that is indeed the case and not just a product of me overworking myself, I would like you to just tell me what it is that I am evidently not getting.

I wrote a 3-part series to introduce the curves (in context with other attempts at improving fidelity) for a headphone blog. Sean Olive later read and plugged this on his Twitter, so I assume I did not screw this up. The curve essentially uses a dummy torso that broadly resembles average human features (ears, face etc.), with calibrated mics inside the ears. They then played back their reference setup in their reference room (validated by the seminal Harman speaker studies) with this dummy at the sweet spot. Thus, the acoustical output is already a combination of speaker + room - ie. direct sound and reflected sound when it reaches this torso.

The tonal balance of both direct and reflected (ie. delayed) sound is very similar, owing to the intrinsic flat, smooth FR (and more critically) dispersion. So it's an attempt to translate the validated Harman speaker setup to headphones, but with approximations taken as headphone listening is much more sensitive to individual differences in morphology. Because in a real speaker setup, your own body and ears are engaging with the speakers. In the Harman curve setup, you are reproducing with speakers, the net result of speaker output, room contribution (which are already validated by the speaker studies) and the dummy torso as a surrogate for your body to approximate you sitting in that same room. And the reason why you would want to sit in that room, is because of what the Harman speaker preference studies (and their associated literature on room design etc.) established.

That said, as I point out in my article, particularly in part 3, your intuition is also right in that the Harman headphone curve is only relevant if you accept the premise that approximating the Harman reference speaker setup with headphones is a desirable goal to aim towards. There are other, fundamentally-sound premises, both analytical and experimental, that can yield different curves. They can't promise to be preferable, but perhaps you could pick the premise that you most identify with and tweak from there.

 

[CJ Miller]

This looks like something you'd see in the saw movies. There's just no way I'd wear those.

 

[tomtoo]

This looks like something you'd see in the saw movies. There's just no way I'd wear those.

I can see it. Gigawatts of tubeamps feed them.

 

[Nathan Raymond]

An interesting thing you can do with headphones this 'open' is some people keep their subwoofers on while using these. I've tried it and it's okay. I probably wouldn't trust things to be completely flat or easily measurable with a mix of a subwoofer or two + headphones, but it can make it more fun.

I wonder if these would be a good candidate for the body bass shakers like Woojer has? https://www.woojer.com/

 

[Jake71]

Interesting headphone, but I'm not sure how comfortable I'd be with large powerful neodymium magnets that close to my head.

 

[Sherwood]

I’m curious about how well the shape of the SR1a coupled to the GRAS 45CA.
In my time listening to the headphone, I’ve noticed fit is very important, and differences in fit manifest themselves as notable differences in sound. Specifically, the even pressure of the pad that runs in front of your ear seems to be important.
I am far from a speaker designer, but my understanding of that pad is that it effectively coupled the speaker to your head, creating a kind of baffle which supports the bass response. When listening, I can lift a speaker away from my head, decoupling the pad, and hear the bass fall off sharply. From the shape of the GRAS, it looks like that pad would not be able to make a very good seal with the device.
Of course, Amir’s subjective listening opinion is also of a bass-shy headphone, but it’s not what I’ve found with mine.

 

[solderdude]

There is no pad and no seal on the SR1A. It's the reason for the roll-off. This is a VERY open headphone by design.
It is a ribbon speaker suspended in free air on a small baffle.
The 'wings' on the sides act as baffles preventing the lower frequencies to 'short' themselves at short distances.

 

[Sherwood]

There are two pads per side, one on top of the ear and one long pad in front of it. The pad on the top is similar to the Mysphere and K1000, but the long pad in front of the ear does create a kind of seal, which is unique to the Raal.

 

[amirm]

I’m curious about how well the shape of the SR1a coupled to the GRAS 45CA.

I experiment fair bit to get the highest SPL via placement with all headphones. Whatever vagaries remain would also exist when you wear them. Indeed with instrumentation I am able to place them more perfectly on the fixture than a real person would. The flat sides of the GRAS fixture actually make it easier to get a good fit than a real head/HATS would. Repeatability as such is far better with 45CA than HATS in general.

 

[Sherwood]

I experiment fair bit to get the highest SPL via placement with all headphones. Whatever vagaries remain would also exist when you wear them. Indeed with instrumentation I am able to place them more perfectly on the fixture than a real person would. The flat sides of the GRAS fixture actually make it easier to get a good fit than a real head/HATS would. Repeatability as such is far better with 45CA than HATS in general.

Thanks, Amir, I appreciate it. Highest SPL is exactly what I do when I put them on, but of course I'm not a measurement device.

 

[Sherwood]

Also, @amirm, I just got the Jotunheim R in and copied your EQ settings. It's a great change. I have the HD800s here as well, and AB'ing through the RME DAC FS leaves me with a clear preference for the Raals. I am a panel speaker kind of guy in theory, but I haven't had any in my home for a decade. I'm willing to look pretty ridiculous personally, but I don't want my house to look ridiculous, too.

 

[bennybbbx]

I have not bothered to calibrate my measurement gear so can't give you SPL ratings. Subjectively I can tell you that if the HD-650 is 10 on max loudness, the SR1a starts to get distorted in highs around 5. It can get as loud as 7 and then it won't get any louder and/or will clip. Comfortable long term listening would be around 3 to 4 so it is definitely usable. At 7 I can tolerate its level but it is loud.

And I should clarify that at 10 the HD-650 is literally resonating my earlobes. So that is not a usable level either other than for quick testing.

I see in your pictures you have the position of the headphone as other headphones too. to get real better sound more simular to speaker with such headphones the systems need rotate so sound come more from front. but this reduce level. I try to measure now with sound level meter my headphones and repair them. now i can get 82 db with good bass when boost 4 db in this position. this is real good now. there was some foam material inside. i remove this complete and clean it, now i get not such clicks on low volume. the foam material get destroyed over the years it crump when i remove it. can see in the _1 picture. so if somebody have a K1000 that sound as the membrane is damged, remove the foam can bring them to much better sound. that it sound diffrent i can not hear

 

[Duncan_McCloud]

For the next phase of testing I created a set of filters in Roon player equalizer:

There is a combo of 3 filters to the left for bass. I had created this for other headphones and it worked very well here. It boosts the lows with two filters and then truncates the deep bass to avoid distortion. Note that the levels are pulled down a bit also to avoid pipeline overflow. The subject impact of this bass boost was very large. It heavily transformed the sound, making the SR1a much more balanced and fuller.

Next I attacked the 2 kHz peak. That was effective as well and took out some of that upper mid-range boost that was giving that "light" sound but which was out of balance.

I was surprised by the next filter at 5.6 kHz. It not only correct the spectrum but also seemed to reduce high frequency distortion! Maybe there is some panel resonance there.

I was not sure if the last filter was necessary as the higher the frequency, the less trust I have in headphone measurements. But it indeed was effective in reducing those upper notes that stood out way too much.

All together the transformation was quite impressive. You still had that "panel open sound" but now with much more balanced frequency response. Could now listen for a long time without saying, "oh wait, was that correct?"

Hi @amirm ,
I was curious to test this EQ settings, just to find out if there was a way to have a better bass, since lot of people says SR1a is bass light.
I was focused on the bass and I have applied the same band you have posted. I have used the following environment:

RAAL SR1a
JOTR
RME ADI2DAC
ROON with your EQ Setting

Track: Pink Floyd - Echoes In the first 2 minutes there is low bass which is mostly not covered by everything else.

I have found the bass with your EQ more present without any doubt, but also boomy and distorted.

That's not criticism. I just want to better understand if I am doing something wrong on my setup, or maybe it's just a matter of different flavours.
I am also not Bass Heavy and coming from an HD800S, so maybe I am not just used to similar bass impact.

Thanks and Best Regards

 

[YSC]

Hi @amirm ,
I was curious to test this EQ settings, just to find out if there was a way to have a better bass, since lot of people says SR1a is bass light.
I was focused on the bass and I have applied the same band you have posted. I have used the following environment:

RAAL SR1a
JOTR
RME ADI2DAC
ROON with your EQ Setting

Track: Pink Floyd - Echoes In the first 2 minutes there is low bass which is mostly not covered by everything else.

I have found the bass with your EQ more present without any doubt, but also boomy and distorted.

That's not criticism. I just want to better understand if I am doing something wrong on my setup, or maybe it's just a matter of different flavours.
I am also not Bass Heavy and coming from an HD800S, so maybe I am not just used to similar bass impact.

Thanks and Best Regards

the boomy seems related to the Harman Preference target, which by default have around 8db more bass than in room flat FR speaker, so it seems more of a bassy tuning for enjoyment than neutral and if you are not used to will sound boomy

 

[Sherwood]

I use something very close to Amir's EQ in Roon, and after adjusting levels to ensure I wasn't clipping I don't hear any distortion at my listening levels. What are the rest of your Roon DSP settings like?

 

[amirm]

I have found the bass with your EQ more present without any doubt, but also boomy and distorted.

You have to track down and eliminate sources of distortion as noted. With that in there, all bets are off. Make sure you have headroom allowance option in Roon on with the indicator so that you can see if clipping is occurring. Also, it is possible there is not enough headroom in Schiit JOTR to handle this EQ.

Also, harmonics of deep bass are still bass and can sound like upper bass is increased. So that is another reason to find the source of that distortion and fix it.

Finally, the sub bass EQ for this headphone was adjusted by ear and not as optimized as I am doing now with newer reviews.