RAAL-Requisite SR1a ear-phones

I am really well equipped with great headphones and amps that I love and I don’t need to buy any more - haaa hahahaha, thank you, I’ll be here all week.

Seriously, I use planar magnetics and love the Hifiman Susvara and Audeze LCD-4z. But I became interested in the very unusual RAAL-Requisite SR1a phones, they have been written up in several places since the fall. Lots of glowing commentary, I’ll put some links below. If you want to hear about how they removed veils from the music you have to go there, I don’t do reviews. (Yes, they are perfectly satisfactory.)

But there is some interesting technology. The SR1a are ribbon speakers that hang beside your head, there are no cups, they don’t seal to your head, you can adjust the angle of them. No isolation, of course. It’s like having a pair of micro-Magneplanars hanging there.

However, here is the quirk: you can’t drive them with a regular headphone amp. The problem is that their impedance is 0.2 ohm. Any amp will see that as a dead short, and will either fry or go into protection. RAAL provides an adapter box for a speaker amp of at least 100 W amp which diverts most of the power into heat. But from what I have read, a better solution is an amp dedicated to this kind of load. RAAL offers one, and Schiit has released one, the Jotunheim R, which is what I got.

But note that this is a very unusual amp that works only for the SR1a, you can’t plug in regular phones. We have recently had a discussion here of the Susvara which are very demanding to drive. I saw a note that at a 120 dB peak, they draw 290 mA (6 W into their 60 ohms), which the Benchmark HPA4 and Chord Hugo TT2 can deliver but the portable Hugo 2 and an iPhone cannot. Well, the Jotunheim R can deliver 13,000 mA of current into the SR1a 0.2 ohms. 13 amps! Holy! And the SR1a specs efficiency as 91 dB/W. Ok, 91 dB, that’s normal, ho hum. No, no, that’s 91 dB per watt, not milliwatt. Holy holy!

On the other hand the Jotunheim R delivers only 5 V, so if you dared plug in the Susvara you would get less than 0.5 W. So current strength is not the same as voltage strength, power delivery must be match the impedance of the phones. “How much do you need to turn up the volume control?” The volume control is like the accelerator pedal in a car, it’s how you communicate a wish, but pressing the pedal to the metal has different effects in a Ferrari V12 and a Prius or an eighteen-wheeler. This whole thing is a master-class in Ohm’s Law.

This also leads to complications for setting up different headphones. All these versions with different requirements — SR1a, Susvara, Stax electrostatics, mainstream planars or dynamics, IEMs — increasingly require different amps, some are mutually compatible but not all. And each needs a streaming end point and DAC. Ok, you can plug multiple amps into one DAC but it is often a hassle involving cables on the backs of boxes. And while I like my Chord stack, I don’t want to buy several of those, one for each headphone. I could get cheaper DACs, but getting the greatest headphones and running them off a mid-fi DAC doesn’t make much sense.

Plus there is another problem: some of these headphones need some DSP, the SR1a were originally designed for monitoring during recordings and are aggressively neutral, some consumers may prefer a “house curve”, I don’t know yet, am experimenting but I think I will. And the Audeze have custom convolution filters, and of course speakers often have room correction. This means if you plug these chains into the same streamer, Roon sees them as the same endpoint, and you have to manually switch DSP preset, and switch cables and turn amps on and off. Oh, the horror! Ok, I can live with that, but knowing myself I will forget, using the wrong DSP preset will only impair the sound, plugging the wrong thing in the wrong jack may damage something.

Anyway, lovely so far.

Reviews and descriptions:


I heard them at release in canjam Singapore and you mention of a pair of speakers hanging beside your hear head is pretty apt. Wasn’t a fan…and yeah they blow amps easily as was apparent as one of the demo pairs was out of order due to a fried schiit monoblock

I have these. Stunning! Just make you want to listen to music. I use them with the Schiit Jot-R amp. I don’t know if that is ideal in every case and based on a recommendation I’ve ordered an iFi tube buffer to try out.

I’m not really interested in the adapter box + amp. I’d like to see more dedicated RAAL headphone amps that could give us something else besides the Jot-R. Or include a tube version of the Jot-R. In another thread someone inserted a tube preamp between source and the Jot-R.

My DAC has a built-in headphone amp, so when the RAALs are not optimum I use that with Meze Empyreans.

A post about some stunning music with the SR1a

My wife is trying to forget her opinion if how I look in my HD800 phones. I would be ridiculed to my last breath if…:slight_smile:
The hd800 leak being open, does it sound to others like you have two speakers strapped to your head?

Nobody here but me, so far, so I can’t tell.

But I can say about leakage the other way, yesterday I was exploring an album on the SR1a and I was disappointed, not as crisp as I was used to, and a little soft, and I couldn’t increase the volume on the Jotunheim amp — I had neglected to switch zone, was listening to the speakers.

Wrt the looks, they would fit as props in Blade Runner. Not sure if that would be a plus or a minus for your wife.

I mentioned above the complexities of connecting the device chain together for different devices. I just found a problem, and the cause, and the solution, for one such.

For my Susvara cans I listen with my Chord M-Scaler + Hugo TT 2, a wonderful setup. Since that’s my best DAC I want to use that for the SR1a, but of course feeding the Jotunheim R special amp for the SR1a. The TT 2 has an unusual circuit, instead of a normal line output plus a separate power amp for headphones, the line drive straight out of the DAC has enough power to drive headphones and even some speakers, 18 W with balanced connection, so that’s how I use it with the Susvara. For connecting to the Jotunheim R, I unplugged the Susvara and used a balanced connection to the Jot — yes, it’s clumsy, I’ll have to figure something out, short of 10k for another Chord stack.

To avoid having to adjust the volume when I go back to the Susvara, I left it as is and set the final level with the Jot volume control.

But I was getting occasional pops and cracks and image shifts. I was pretty certain I wasn’t overdriving the SR1a ribbons, I’m not a metal head. Nor was I asking too much of the Jot output, with its 13 A capability. And I knew I wasn’t overdriving the TT 2 because it sounds great with the Susvara. But I realized the level coming out of the TT 2 is higher than a normal line level, I was overdriving the Jot input.

The TT 2 has a DAC mode which sets the output to normal line level and bypasses the volume control, so switching to that mode solved it, the Jot was happy with the normal level, so was the SR1a, and so was I. And when I go back to the Susvara I have to switch the TT 2 back to AMP mode, as well as shift the cabling. (I was previously afraid of using DAC mode, I thought if I forget to switch back to AMP mode when I connect the Susvara I would fry them with the volume control, I thought that was max level, but I am apparently way above line level for the Susvara.)

Complexities, as I discussed. I have to streamline this.

I think I have a solution to the complexity which cost significantly less than a second Chord stack.

The Chord Hugo TT 2 has a clever mode switch: the DAC and AMP modes you have to switch manually, but the third mode HEADPHONES switches automatically, when you plug headphones into the jack in front it automatically turns off the outputs on the back, both balanced and unbalanced. Ok, cheap receivers have done that since forever, but the Chord maintains separate memories for settings for each mode.

And from a sound quality perspective, all of these jacks and modes use the same electronics, there is no disadvantage to plug into the 1/4” jack instead of the rear.

So I got a short 1/4” to RCA cable and use that to drive the Jotunheim R. No risk of forgetting to adjust settings and frying the headphones, no futzing around with cables in the back. I set the volume of the headphone jack at 0 dB which is the same as line output, while the AMP mode is set to +10 to drive the Susvara.

Of course, if I plug in other cans with more normal requirements I have to adjust the volume, easily done.

Convenient and no risk of damage.

I am powering the SR1a with the Devialet 120 + RAAL’s interface. Because Devialet prides themselves for being digital pretty much all the way to the speaker output, the RAALs behave consequently as sharp as a surgeon’s knife. Which I thoroughly enjoy, yet it can be fatiguing to be honest. Anybody volunteered to create a SR1a DSP such as the ones for Audeze? I’d love to try some, especially one that would emulate tubes. Looking forward!

Audiophile Style gushed over the RAAL SR1a.
He has just written about the Schiit Jotunheim R amp designed specifically for the SR1a (which I also use).